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Merge branch 'master' of https://github.com/ClickHouse/ClickHouse into gyuton-DOCSUP-6073-Document_mapContains_mapKeys_mapValues_functions

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This commit is contained in:
George 2021-02-21 15:16:11 +03:00
commit 159c619407
892 changed files with 26132 additions and 8229 deletions
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32
.github/workflows/codeql-analysis.yml vendored
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@ -1,32 +0,0 @@
# See the example here: https://github.com/github/codeql-action
name: "CodeQL Scanning"
on:
schedule:
- cron: '0 19 * * *'
jobs:
CodeQL-Build:
runs-on: self-hosted
timeout-minutes: 1440
steps:
- name: Checkout repository
uses: actions/checkout@v2
with:
fetch-depth: 2
submodules: 'recursive'
- name: Initialize CodeQL
uses: github/codeql-action/init@v1
with:
languages: cpp
- run: sudo apt-get update && sudo apt-get install -y git cmake python ninja-build gcc-10 g++-10 && mkdir build
- run: cd build && CC=gcc-10 CXX=g++-10 cmake ..
- run: cd build && ninja
- name: Perform CodeQL Analysis
uses: github/codeql-action/analyze@v1

6
.gitignore vendored
View File

@ -137,3 +137,9 @@ website/package-lock.json
/prof
*.iml
# data store
/programs/server/data
/programs/server/metadata
/programs/server/store

2
.gitmodules vendored
View File

@ -220,4 +220,4 @@
url = https://github.com/ClickHouse-Extras/boringssl.git
[submodule "contrib/NuRaft"]
path = contrib/NuRaft
url = https://github.com/eBay/NuRaft.git
url = https://github.com/ClickHouse-Extras/NuRaft.git

4
README.md
View File

@ -11,9 +11,5 @@ ClickHouse® is an open-source column-oriented database management system that a
* [Slack](https://join.slack.com/t/clickhousedb/shared_invite/zt-ly9m4w1x-6j7x5Ts_pQZqrctAbRZ3cg) and [Telegram](https://telegram.me/clickhouse_en) allow to chat with ClickHouse users in real-time.
* [Blog](https://clickhouse.yandex/blog/en/) contains various ClickHouse-related articles, as well as announcements and reports about events.
* [Code Browser](https://clickhouse.tech/codebrowser/html_report/ClickHouse/index.html) with syntax highlight and navigation.
* [Yandex.Messenger channel](https://yandex.ru/chat/#/join/20e380d9-c7be-4123-ab06-e95fb946975e) shares announcements and useful links in Russian.
* [Contacts](https://clickhouse.tech/#contacts) can help to get your questions answered if there are any.
* You can also [fill this form](https://clickhouse.tech/#meet) to meet Yandex ClickHouse team in person.
## Upcoming Events
* [Chinese ClickHouse Meetup (online)](http://hdxu.cn/8KxZE) on 6 February 2021.

9
base/common/arithmeticOverflow.h
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@ -1,6 +1,8 @@
#pragma once
#include <common/extended_types.h>
#include <common/defines.h>
namespace common
{
@ -156,4 +158,11 @@ namespace common
return false;
return (x * y) / y != x;
}
/// Multiply and ignore overflow.
template <typename T1, typename T2>
inline auto NO_SANITIZE_UNDEFINED mulIgnoreOverflow(T1 x, T2 y)
{
return x * y;
}
}

18
base/daemon/BaseDaemon.cpp
View File

@ -152,7 +152,7 @@ static void signalHandler(int sig, siginfo_t * info, void * context)
if (sig != SIGTSTP) /// This signal is used for debugging.
{
/// The time that is usually enough for separate thread to print info into log.
sleepForSeconds(10);
sleepForSeconds(20); /// FIXME: use some feedback from threads that process stacktrace
call_default_signal_handler(sig);
}
@ -311,7 +311,8 @@ private:
if (stack_trace.getSize())
{
/// Write bare stack trace (addresses) just in case if we will fail to print symbolized stack trace.
/// NOTE This still require memory allocations and mutex lock inside logger. BTW we can also print it to stderr using write syscalls.
/// NOTE: This still require memory allocations and mutex lock inside logger.
/// BTW we can also print it to stderr using write syscalls.
std::stringstream bare_stacktrace;
bare_stacktrace << "Stack trace:";
@ -324,7 +325,7 @@ private:
/// Write symbolized stack trace line by line for better grep-ability.
stack_trace.toStringEveryLine([&](const std::string & s) { LOG_FATAL(log, s); });
#if defined(__linux__)
#if defined(OS_LINUX)
/// Write information about binary checksum. It can be difficult to calculate, so do it only after printing stack trace.
String calculated_binary_hash = getHashOfLoadedBinaryHex();
if (daemon.stored_binary_hash.empty())
@ -415,7 +416,9 @@ static void sanitizerDeathCallback()
else
log_message = "Terminate called without an active exception";
static const size_t buf_size = 1024;
/// POSIX.1 says that write(2)s of less than PIPE_BUF bytes must be atomic - man 7 pipe
/// And the buffer should not be too small because our exception messages can be large.
static constexpr size_t buf_size = PIPE_BUF;
if (log_message.size() > buf_size - 16)
log_message.resize(buf_size - 16);
@ -561,6 +564,7 @@ void debugIncreaseOOMScore()
{
DB::WriteBufferFromFile buf("/proc/self/oom_score_adj");
buf.write(new_score.c_str(), new_score.size());
buf.close();
}
catch (const Poco::Exception & e)
{
@ -783,7 +787,7 @@ void BaseDaemon::initializeTerminationAndSignalProcessing()
/// Setup signal handlers.
/// SIGTSTP is added for debugging purposes. To output a stack trace of any running thread at anytime.
addSignalHandler({SIGABRT, SIGSEGV, SIGILL, SIGBUS, SIGSYS, SIGFPE, SIGPIPE, SIGTSTP}, signalHandler, &handled_signals);
addSignalHandler({SIGABRT, SIGSEGV, SIGILL, SIGBUS, SIGSYS, SIGFPE, SIGPIPE, SIGTSTP, SIGTRAP}, signalHandler, &handled_signals);
addSignalHandler({SIGHUP, SIGUSR1}, closeLogsSignalHandler, &handled_signals);
addSignalHandler({SIGINT, SIGQUIT, SIGTERM}, terminateRequestedSignalHandler, &handled_signals);
@ -986,7 +990,7 @@ void BaseDaemon::setupWatchdog()
if (errno == ECHILD)
{
logger().information("Child process no longer exists.");
_exit(status);
_exit(WEXITSTATUS(status));
}
if (WIFEXITED(status))
@ -1020,7 +1024,7 @@ void BaseDaemon::setupWatchdog()
/// Automatic restart is not enabled but you can play with it.
#if 1
_exit(status);
_exit(WEXITSTATUS(status));
#else
logger().information("Will restart.");
if (argv0)

6
base/daemon/BaseDaemon.h
View File

@ -83,7 +83,7 @@ public:
template <class T>
void writeToGraphite(const std::string & key, const T & value, const std::string & config_name = DEFAULT_GRAPHITE_CONFIG_NAME, time_t timestamp = 0, const std::string & custom_root_path = "")
{
auto writer = getGraphiteWriter(config_name);
auto *writer = getGraphiteWriter(config_name);
if (writer)
writer->write(key, value, timestamp, custom_root_path);
}
@ -91,7 +91,7 @@ public:
template <class T>
void writeToGraphite(const GraphiteWriter::KeyValueVector<T> & key_vals, const std::string & config_name = DEFAULT_GRAPHITE_CONFIG_NAME, time_t timestamp = 0, const std::string & custom_root_path = "")
{
auto writer = getGraphiteWriter(config_name);
auto *writer = getGraphiteWriter(config_name);
if (writer)
writer->write(key_vals, timestamp, custom_root_path);
}
@ -99,7 +99,7 @@ public:
template <class T>
void writeToGraphite(const GraphiteWriter::KeyValueVector<T> & key_vals, const std::chrono::system_clock::time_point & current_time, const std::string & custom_root_path)
{
auto writer = getGraphiteWriter();
auto *writer = getGraphiteWriter();
if (writer)
writer->write(key_vals, std::chrono::system_clock::to_time_t(current_time), custom_root_path);
}

8
cmake/find/ccache.cmake
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@ -37,15 +37,13 @@ if (CCACHE_FOUND AND NOT COMPILER_MATCHES_CCACHE)
#
# - 4.0+ ccache always includes this environment variable into the hash
# of the manifest, which do not allow to use previous cache,
# - 4.2+ ccache ignores SOURCE_DATE_EPOCH under time_macros sloppiness.
# - 4.2+ ccache ignores SOURCE_DATE_EPOCH for every file w/o __DATE__/__TIME__
#
# So for:
# - 4.2+ time_macros sloppiness is used,
# - 4.2+ does not require any sloppiness
# - 4.0+ will ignore SOURCE_DATE_EPOCH environment variable.
if (CCACHE_VERSION VERSION_GREATER_EQUAL "4.2")
message(STATUS "Use time_macros sloppiness for ccache")
set_property (GLOBAL PROPERTY RULE_LAUNCH_COMPILE "${CCACHE_FOUND} --set-config=sloppiness=time_macros")
set_property (GLOBAL PROPERTY RULE_LAUNCH_LINK "${CCACHE_FOUND} --set-config=sloppiness=time_macros")
message(STATUS "ccache is 4.2+ no quirks for SOURCE_DATE_EPOCH required")
elseif (CCACHE_VERSION VERSION_GREATER_EQUAL "4.0")
message(STATUS "Ignore SOURCE_DATE_EPOCH for ccache")
set_property (GLOBAL PROPERTY RULE_LAUNCH_COMPILE "env -u SOURCE_DATE_EPOCH ${CCACHE_FOUND}")

4
cmake/find/nuraft.cmake
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@ -11,7 +11,7 @@ if (NOT EXISTS "${ClickHouse_SOURCE_DIR}/contrib/NuRaft/CMakeLists.txt")
return()
endif ()
if (NOT OS_FREEBSD)
if (NOT OS_FREEBSD AND NOT OS_DARWIN)
set (USE_NURAFT 1)
set (NURAFT_LIBRARY nuraft)
@ -20,5 +20,5 @@ if (NOT OS_FREEBSD)
message (STATUS "Using NuRaft=${USE_NURAFT}: ${NURAFT_INCLUDE_DIR} : ${NURAFT_LIBRARY}")
else()
set (USE_NURAFT 0)
message (STATUS "Using internal NuRaft library on FreeBSD is not supported")
message (STATUS "Using internal NuRaft library on FreeBSD and Darwin is not supported")
endif()

2
contrib/NuRaft vendored

@ -1 +1 @@
Subproject commit 410bd149da84cdde60b4436b02b738749f4e87e1
Subproject commit 7adf7ae33e7d5c307342431b577c8ab1025ee793

2
contrib/boost vendored

@ -1 +1 @@
Subproject commit 8e259cd2a6b60d75dd17e73432f11bb7b9351bb1
Subproject commit 48f40ebb539220d328958f8823b094c0b07a4e79

7
contrib/nuraft-cmake/CMakeLists.txt
View File

@ -30,7 +30,12 @@ set(SRCS
add_library(nuraft ${SRCS})
target_compile_definitions(nuraft PRIVATE USE_BOOST_ASIO=1 BOOST_ASIO_STANDALONE=1)
if (NOT OPENSSL_SSL_LIBRARY OR NOT OPENSSL_CRYPTO_LIBRARY)
target_compile_definitions(nuraft PRIVATE USE_BOOST_ASIO=1 BOOST_ASIO_STANDALONE=1 SSL_LIBRARY_NOT_FOUND=1)
else()
target_compile_definitions(nuraft PRIVATE USE_BOOST_ASIO=1 BOOST_ASIO_STANDALONE=1)
endif()
target_include_directories (nuraft SYSTEM PRIVATE ${LIBRARY_DIR}/include/libnuraft)
# for some reason include "asio.h" directly without "boost/" prefix.

8
docker/server/README.md
View File

@ -56,7 +56,7 @@ $ echo 'SELECT version()' | curl 'http://localhost:8123/' --data-binary @-
20.12.3.3
```
### Volumes
### Volumes
Typically you may want to mount the following folders inside your container to archieve persistency:
@ -76,7 +76,7 @@ You may also want to mount:
* `/etc/clickhouse-server/usert.d/*.xml` - files with use settings adjustmenets
* `/docker-entrypoint-initdb.d/` - folder with database initialization scripts (see below).
### Linux capabilities
### Linux capabilities
ClickHouse has some advanced functionality which requite enabling several [linux capabilities](https://man7.org/linux/man-pages/man7/capabilities.7.html).
@ -113,10 +113,10 @@ $ docker run --rm -e CLICKHOUSE_UID=0 -e CLICKHOUSE_GID=0 --name clickhouse-serv
### How to create default database and user on starting
Sometimes you may want to create user (user named `default` is used by default) and database on image starting. You can do it using environment variables `CLICKHOUSE_DB`, `CLICKHOUSE_USER` and `CLICKHOUSE_PASSWORD`:
Sometimes you may want to create user (user named `default` is used by default) and database on image starting. You can do it using environment variables `CLICKHOUSE_DB`, `CLICKHOUSE_USER`, `CLICKHOUSE_DEFAULT_ACCESS_MANAGEMENT` and `CLICKHOUSE_PASSWORD`:
```
$ docker run --rm -e CLICKHOUSE_DB=my_database -e CLICKHOUSE_USER=username -e CLICKHOUSE_PASSWORD=password -p 9000:9000/tcp yandex/clickhouse-server
$ docker run --rm -e CLICKHOUSE_DB=my_database -e CLICKHOUSE_USER=username -e CLICKHOUSE_DEFAULT_ACCESS_MANAGEMENT=1 -e CLICKHOUSE_PASSWORD=password -p 9000:9000/tcp yandex/clickhouse-server
```
## How to extend this image

2
docker/server/alpine-build.sh
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@ -54,8 +54,10 @@ docker cp -L "${ubuntu20image}":/lib/x86_64-linux-gnu/libm.so.6 "${CONTAIN
docker cp -L "${ubuntu20image}":/lib/x86_64-linux-gnu/libpthread.so.0 "${CONTAINER_ROOT_FOLDER}/lib"
docker cp -L "${ubuntu20image}":/lib/x86_64-linux-gnu/librt.so.1 "${CONTAINER_ROOT_FOLDER}/lib"
docker cp -L "${ubuntu20image}":/lib/x86_64-linux-gnu/libnss_dns.so.2 "${CONTAINER_ROOT_FOLDER}/lib"
docker cp -L "${ubuntu20image}":/lib/x86_64-linux-gnu/libnss_files.so.2 "${CONTAINER_ROOT_FOLDER}/lib"
docker cp -L "${ubuntu20image}":/lib/x86_64-linux-gnu/libresolv.so.2 "${CONTAINER_ROOT_FOLDER}/lib"
docker cp -L "${ubuntu20image}":/lib64/ld-linux-x86-64.so.2 "${CONTAINER_ROOT_FOLDER}/lib64"
docker cp -L "${ubuntu20image}":/etc/nsswitch.conf "${CONTAINER_ROOT_FOLDER}/etc"
docker build "$DOCKER_BUILD_FOLDER" -f Dockerfile.alpine -t "${DOCKER_IMAGE}:${VERSION}-alpine" --pull
rm -rf "$CONTAINER_ROOT_FOLDER"

2
docker/server/entrypoint.sh
View File

@ -54,6 +54,7 @@ FORMAT_SCHEMA_PATH="$(clickhouse extract-from-config --config-file "$CLICKHOUSE_
CLICKHOUSE_USER="${CLICKHOUSE_USER:-default}"
CLICKHOUSE_PASSWORD="${CLICKHOUSE_PASSWORD:-}"
CLICKHOUSE_DB="${CLICKHOUSE_DB:-}"
CLICKHOUSE_ACCESS_MANAGEMENT="${CLICKHOUSE_DEFAULT_ACCESS_MANAGEMENT:-0}"
for dir in "$DATA_DIR" \
"$ERROR_LOG_DIR" \
@ -97,6 +98,7 @@ if [ -n "$CLICKHOUSE_USER" ] && [ "$CLICKHOUSE_USER" != "default" ] || [ -n "$CL
</networks>
<password>${CLICKHOUSE_PASSWORD}</password>
<quota>default</quota>
<access_management>${CLICKHOUSE_ACCESS_MANAGEMENT}</access_management>
</${CLICKHOUSE_USER}>
</users>
</yandex>

1
docker/test/fasttest/Dockerfile
View File

@ -47,6 +47,7 @@ RUN apt-get update \
expect \
fakeroot \
git \
gdb \
gperf \
lld-${LLVM_VERSION} \
llvm-${LLVM_VERSION} \

22
docker/test/fasttest/run.sh
View File

@ -107,6 +107,18 @@ function start_server
fi
echo "ClickHouse server pid '$server_pid' started and responded"
echo "
handle all noprint
handle SIGSEGV stop print
handle SIGBUS stop print
handle SIGABRT stop print
continue
thread apply all backtrace
continue
" > script.gdb
gdb -batch -command script.gdb -p "$server_pid" &
}
function clone_root
@ -120,7 +132,7 @@ function clone_root
git checkout FETCH_HEAD
echo 'Clonned merge head'
else
git fetch
git fetch origin "+refs/pull/$PULL_REQUEST_NUMBER/head"
git checkout "$COMMIT_SHA"
echo 'Checked out to commit'
fi
@ -163,6 +175,7 @@ function clone_submodules
contrib/xz
contrib/dragonbox
contrib/fast_float
contrib/NuRaft
)
git submodule sync
@ -182,6 +195,7 @@ function run_cmake
"-DENABLE_EMBEDDED_COMPILER=0"
"-DENABLE_THINLTO=0"
"-DUSE_UNWIND=1"
"-DENABLE_NURAFT=1"
)
# TODO remove this? we don't use ccache anyway. An option would be to download it
@ -257,6 +271,7 @@ function run_tests
00929_multi_match_edit_distance
01681_hyperscan_debug_assertion
01176_mysql_client_interactive # requires mysql client
01031_mutations_interpreter_and_context
01053_ssd_dictionary # this test mistakenly requires acces to /var/lib/clickhouse -- can't run this locally, disabled
01083_expressions_in_engine_arguments
@ -324,7 +339,7 @@ function run_tests
# Look at DistributedFilesToInsert, so cannot run in parallel.
01460_DistributedFilesToInsert
01541_max_memory_usage_for_user
01541_max_memory_usage_for_user_long
# Require python libraries like scipy, pandas and numpy
01322_ttest_scipy
@ -340,9 +355,10 @@ function run_tests
# JSON functions
01666_blns
01674_htm_xml_coarse_parse
)
time clickhouse-test --hung-check -j 8 --order=random --use-skip-list --no-long --testname --shard --zookeeper --skip "${TESTS_TO_SKIP[@]}" -- "$FASTTEST_FOCUS" 2>&1 | ts '%Y-%m-%d %H:%M:%S' | tee "$FASTTEST_OUTPUT/test_log.txt"
(time clickhouse-test --hung-check -j 8 --order=random --use-skip-list --no-long --testname --shard --zookeeper --skip "${TESTS_TO_SKIP[@]}" -- "$FASTTEST_FOCUS" 2>&1 ||:) | ts '%Y-%m-%d %H:%M:%S' | tee "$FASTTEST_OUTPUT/test_log.txt"
# substr is to remove semicolon after test name
readarray -t FAILED_TESTS < <(awk '/\[ FAIL|TIMEOUT|ERROR \]/ { print substr($3, 1, length($3)-1) }' "$FASTTEST_OUTPUT/test_log.txt" | tee "$FASTTEST_OUTPUT/failed-parallel-tests.txt")

2
docker/test/fuzzer/run-fuzzer.sh
View File

@ -190,7 +190,7 @@ case "$stage" in
# Lost connection to the server. This probably means that the server died
# with abort.
echo "failure" > status.txt
if ! grep -ao "Received signal.*\|Logical error.*\|Assertion.*failed\|Failed assertion.*\|.*runtime error: .*\|.*is located.*\|SUMMARY: MemorySanitizer:.*\|SUMMARY: ThreadSanitizer:.*" server.log > description.txt
if ! grep -ao "Received signal.*\|Logical error.*\|Assertion.*failed\|Failed assertion.*\|.*runtime error: .*\|.*is located.*\|SUMMARY: MemorySanitizer:.*\|SUMMARY: ThreadSanitizer:.*\|.*_LIBCPP_ASSERT.*" server.log > description.txt
then
echo "Lost connection to server. See the logs." > description.txt
fi

2
docker/test/integration/runner/Dockerfile
View File

@ -58,7 +58,7 @@ RUN dockerd --version; docker --version
RUN python3 -m pip install \
PyMySQL \
aerospike \
aerospike==4.0.0 \
avro \
cassandra-driver \
confluent-kafka==1.5.0 \

3
docker/test/performance-comparison/perf.py
View File

@ -44,6 +44,7 @@ parser.add_argument('--port', nargs='*', default=[9000], help="Space-separated l
parser.add_argument('--runs', type=int, default=1, help='Number of query runs per server.')
parser.add_argument('--max-queries', type=int, default=None, help='Test no more than this number of queries, chosen at random.')
parser.add_argument('--queries-to-run', nargs='*', type=int, default=None, help='Space-separated list of indexes of queries to test.')
parser.add_argument('--max-query-seconds', type=int, default=10, help='For how many seconds at most a query is allowed to run. The script finishes with error if this time is exceeded.')
parser.add_argument('--profile-seconds', type=int, default=0, help='For how many seconds to profile a query for which the performance has changed.')
parser.add_argument('--long', action='store_true', help='Do not skip the tests tagged as long.')
parser.add_argument('--print-queries', action='store_true', help='Print test queries and exit.')
@ -323,7 +324,7 @@ for query_index in queries_to_run:
server_seconds += elapsed
print(f'query\t{query_index}\t{run_id}\t{conn_index}\t{elapsed}')
if elapsed > 10:
if elapsed > args.max_query_seconds:
# Stop processing pathologically slow queries, to avoid timing out
# the entire test task. This shouldn't really happen, so we don't
# need much handling for this case and can just exit.

4
docker/test/stateful/run.sh
View File

@ -60,4 +60,8 @@ fi
# more idiologically correct.
read -ra ADDITIONAL_OPTIONS <<< "${ADDITIONAL_OPTIONS:-}"
if [[ -n "$USE_DATABASE_REPLICATED" ]] && [[ "$USE_DATABASE_REPLICATED" -eq 1 ]]; then
ADDITIONAL_OPTIONS+=('--replicated-database')
fi
clickhouse-test --testname --shard --zookeeper --no-stateless --hung-check --print-time "$SKIP_LIST_OPT" "${ADDITIONAL_OPTIONS[@]}" "$SKIP_TESTS_OPTION" 2>&1 | ts '%Y-%m-%d %H:%M:%S' | tee test_output/test_result.txt

7
docker/test/stateless/Dockerfile
View File

@ -3,6 +3,9 @@ FROM yandex/clickhouse-test-base
ARG odbc_driver_url="https://github.com/ClickHouse/clickhouse-odbc/releases/download/v1.1.4.20200302/clickhouse-odbc-1.1.4-Linux.tar.gz"
RUN echo "deb [trusted=yes] http://repo.mysql.com/apt/ubuntu/ bionic mysql-5.7" >> /etc/apt/sources.list \
&& apt-key adv --keyserver keyserver.ubuntu.com --recv-keys 8C718D3B5072E1F5
RUN apt-get update -y \
&& env DEBIAN_FRONTEND=noninteractive \
apt-get install --yes --no-install-recommends \
@ -13,6 +16,7 @@ RUN apt-get update -y \
ncdu \
netcat-openbsd \
openssl \
protobuf-compiler \
python3 \
python3-lxml \
python3-requests \
@ -23,7 +27,8 @@ RUN apt-get update -y \
telnet \
tree \
unixodbc \
wget
wget \
mysql-client=5.7*
RUN pip3 install numpy scipy pandas

4
docker/test/stateless/run.sh
View File

@ -57,6 +57,10 @@ function run_tests()
ADDITIONAL_OPTIONS+=('4')
fi
if [[ -n "$USE_DATABASE_REPLICATED" ]] && [[ "$USE_DATABASE_REPLICATED" -eq 1 ]]; then
ADDITIONAL_OPTIONS+=('--replicated-database')
fi
clickhouse-test --testname --shard --zookeeper --hung-check --print-time \
--test-runs "$NUM_TRIES" \
"$SKIP_LIST_OPT" "${ADDITIONAL_OPTIONS[@]}" 2>&1 \

10
docker/test/stateless_pytest/Dockerfile
View File

@ -5,7 +5,10 @@ RUN apt-get update -y && \
apt-get install -y --no-install-recommends \
python3-pip \
python3-setuptools \
python3-wheel
python3-wheel \
brotli \
netcat-openbsd \
zstd
RUN python3 -m pip install \
wheel \
@ -15,7 +18,10 @@ RUN python3 -m pip install \
pytest-randomly \
pytest-rerunfailures \
pytest-timeout \
pytest-xdist
pytest-xdist \
pandas \
numpy \
scipy
CMD dpkg -i package_folder/clickhouse-common-static_*.deb; \
dpkg -i package_folder/clickhouse-common-static-dbg_*.deb; \

48
docker/test/stress/run.sh
View File

@ -8,16 +8,23 @@ dpkg -i package_folder/clickhouse-server_*.deb
dpkg -i package_folder/clickhouse-client_*.deb
dpkg -i package_folder/clickhouse-test_*.deb
function configure()
{
# install test configs
/usr/share/clickhouse-test/config/install.sh
# for clickhouse-server (via service)
echo "ASAN_OPTIONS='malloc_context_size=10 verbosity=1 allocator_release_to_os_interval_ms=10000'" >> /etc/environment
# for clickhouse-client
export ASAN_OPTIONS='malloc_context_size=10 allocator_release_to_os_interval_ms=10000'
# since we run clickhouse from root
sudo chown root: /var/lib/clickhouse
}
function stop()
{
timeout 120 service clickhouse-server stop
# Wait for process to disappear from processlist and also try to kill zombies.
while kill -9 "$(pidof clickhouse-server)"
do
echo "Killed clickhouse-server"
sleep 0.5
done
clickhouse stop
}
function start()
@ -33,19 +40,26 @@ function start()
tail -n1000 /var/log/clickhouse-server/clickhouse-server.log
break
fi
timeout 120 service clickhouse-server start
# use root to match with current uid
clickhouse start --user root >/var/log/clickhouse-server/stdout.log 2>/var/log/clickhouse-server/stderr.log
sleep 0.5
counter=$((counter + 1))
done
echo "
handle all noprint
handle SIGSEGV stop print
handle SIGBUS stop print
handle SIGABRT stop print
continue
thread apply all backtrace
continue
" > script.gdb
gdb -batch -command script.gdb -p "$(cat /var/run/clickhouse-server/clickhouse-server.pid)" &
}
# install test configs
/usr/share/clickhouse-test/config/install.sh
# for clickhouse-server (via service)
echo "ASAN_OPTIONS='malloc_context_size=10 verbosity=1 allocator_release_to_os_interval_ms=10000'" >> /etc/environment
# for clickhouse-client
export ASAN_OPTIONS='malloc_context_size=10 allocator_release_to_os_interval_ms=10000'
configure
start
@ -64,7 +78,7 @@ clickhouse-client --query "RENAME TABLE datasets.hits_v1 TO test.hits"
clickhouse-client --query "RENAME TABLE datasets.visits_v1 TO test.visits"
clickhouse-client --query "SHOW TABLES FROM test"
./stress --output-folder test_output --skip-func-tests "$SKIP_TESTS_OPTION"
./stress --hung-check --output-folder test_output --skip-func-tests "$SKIP_TESTS_OPTION" && echo "OK" > /test_output/script_exit_code.txt || echo "FAIL" > /test_output/script_exit_code.txt
stop
start

22
docker/test/stress/stress
View File

@ -1,8 +1,9 @@
#!/usr/bin/env python3
# -*- coding: utf-8 -*-
from multiprocessing import cpu_count
from subprocess import Popen, check_call
from subprocess import Popen, call, STDOUT
import os
import sys
import shutil
import argparse
import logging
@ -22,12 +23,15 @@ def get_options(i):
if 0 < i:
options += " --order=random"
if i % 2 == 1:
if i % 3 == 1:
options += " --db-engine=Ordinary"
if i % 3 == 2:
options += ''' --db-engine="Replicated('/test/db/test_{}', 's1', 'r1')"'''.format(i)
# If database name is not specified, new database is created for each functional test.
# Run some threads with one database for all tests.
if i % 3 == 1:
if i % 2 == 1:
options += " --database=test_{}".format(i)
if i == 13:
@ -64,7 +68,8 @@ if __name__ == "__main__":
parser.add_argument("--server-log-folder", default='/var/log/clickhouse-server')
parser.add_argument("--output-folder")
parser.add_argument("--global-time-limit", type=int, default=3600)
parser.add_argument("--num-parallel", default=cpu_count());
parser.add_argument("--num-parallel", default=cpu_count())
parser.add_argument('--hung-check', action='store_true', default=False)
args = parser.parse_args()
func_pipes = []
@ -81,4 +86,13 @@ if __name__ == "__main__":
logging.info("Finished %s from %s processes", len(retcodes), len(func_pipes))
time.sleep(5)
logging.info("All processes finished")
if args.hung_check:
logging.info("Checking if some queries hung")
cmd = "{} {} {}".format(args.test_cmd, "--hung-check", "00001_select_1")
res = call(cmd, shell=True, stderr=STDOUT)
if res != 0:
logging.info("Hung check failed with exit code {}".format(res))
sys.exit(1)
logging.info("Stress test finished")

29
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@ -0,0 +1,29 @@
---
toc_priority:
toc_title:
---
# data_type_name {#data_type-name}
Description.
**Parameters** (Optional)
- `x` — Description. [Type name](relative/path/to/type/dscr.md#type).
- `y` — Description. [Type name](relative/path/to/type/dscr.md#type).
**Examples**
```sql
```
## Additional Info {#additional-info} (Optional)
The name of an additional section can be any, for example, **Usage**.
**See Also** (Optional)
- [link](#)
[Original article](https://clickhouse.tech/docs/en/data_types/<data-type-name>/) <!--hide-->

10
docs/_description_templates/template-function.md
View File

@ -12,16 +12,20 @@ Alias: `<alias name>`. (Optional)
More text (Optional).
**Parameters** (Optional)
**Arguments** (Optional)
- `x` — Description. [Type name](relative/path/to/type/dscr.md#type).
- `y` — Description. [Type name](relative/path/to/type/dscr.md#type).
**Parameters** (Optional, only for parametric aggregate functions)
- `z` — Description. [Type name](relative/path/to/type/dscr.md#type).
**Returned value(s)**
- Returned values list.
- Returned values list.
Type: [Type](relative/path/to/type/dscr.md#type).
Type: [Type name](relative/path/to/type/dscr.md#type).
**Example**

4
docs/_description_templates/template-system-table.md
View File

@ -8,10 +8,14 @@ Columns:
**Example**
Query:
``` sql
SELECT * FROM system.table_name
```
Result:
``` text
Some output. It shouldn't be too long.
```

3
docs/en/engines/database-engines/materialize-mysql.md
View File

@ -93,6 +93,7 @@ ClickHouse has only one physical order, which is determined by `ORDER BY` clause
- Cascade `UPDATE/DELETE` queries are not supported by the `MaterializeMySQL` engine.
- Replication can be easily broken.
- Manual operations on database and tables are forbidden.
- `MaterializeMySQL` is influenced by [optimize_on_insert](../../operations/settings/settings.md#optimize-on-insert) setting. The data is merged in the corresponding table in the `MaterializeMySQL` database when a table in the MySQL server changes.
## Examples of Use {#examples-of-use}
@ -156,4 +157,4 @@ SELECT * FROM mysql.test;
└───┴─────┴──────┘
```
[Original article](https://clickhouse.tech/docs/en/database_engines/materialize-mysql/) <!--hide-->
[Original article](https://clickhouse.tech/docs/en/engines/database-engines/materialize-mysql/) <!--hide-->

3
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View File

@ -12,6 +12,9 @@ List of supported integrations:
- [ODBC](../../../engines/table-engines/integrations/odbc.md)
- [JDBC](../../../engines/table-engines/integrations/jdbc.md)
- [MySQL](../../../engines/table-engines/integrations/mysql.md)
- [MongoDB](../../../engines/table-engines/integrations/mongodb.md)
- [HDFS](../../../engines/table-engines/integrations/hdfs.md)
- [S3](../../../engines/table-engines/integrations/s3.md)
- [Kafka](../../../engines/table-engines/integrations/kafka.md)
- [EmbeddedRocksDB](../../../engines/table-engines/integrations/embedded-rocksdb.md)
- [RabbitMQ](../../../engines/table-engines/integrations/rabbitmq.md)

57
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@ -0,0 +1,57 @@
---
toc_priority: 7
toc_title: MongoDB
---
# MongoDB {#mongodb}
MongoDB engine is read-only table engine which allows to read data (`SELECT` queries) from remote MongoDB collection. Engine supports only non-nested data types. `INSERT` queries are not supported.
## Creating a Table {#creating-a-table}
``` sql
CREATE TABLE [IF NOT EXISTS] [db.]table_name
(
name1 [type1],
name2 [type2],
...
) ENGINE = MongoDB(host:port, database, collection, user, password);
```
**Engine Parameters**
- `host:port` — MongoDB server address.
- `database` — Remote database name.
- `collection` — Remote collection name.
- `user` — MongoDB user.
- `password` — User password.
## Usage Example {#usage-example}
Table in ClickHouse which allows to read data from MongoDB collection:
``` text
CREATE TABLE mongo_table
(
key UInt64,
data String
) ENGINE = MongoDB('mongo1:27017', 'test', 'simple_table', 'testuser', 'clickhouse');
```
Query:
``` sql
SELECT COUNT() FROM mongo_table;
```
``` text
┌─count()─┐
│ 4 │
└─────────┘
```
[Original article](https://clickhouse.tech/docs/en/operations/table_engines/integrations/mongodb/) <!--hide-->

33
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View File

@ -59,10 +59,26 @@ Optional parameters:
- `rabbitmq_max_block_size`
- `rabbitmq_flush_interval_ms`
Required configuration:
Also format settings can be added along with rabbitmq-related settings.
Example:
``` sql
CREATE TABLE queue (
key UInt64,
value UInt64,
date DateTime
) ENGINE = RabbitMQ SETTINGS rabbitmq_host_port = 'localhost:5672',
rabbitmq_exchange_name = 'exchange1',
rabbitmq_format = 'JSONEachRow',
rabbitmq_num_consumers = 5,
date_time_input_format = 'best_effort';
```
The RabbitMQ server configuration should be added using the ClickHouse config file.
Required configuration:
``` xml
<rabbitmq>
<username>root</username>
@ -70,16 +86,12 @@ The RabbitMQ server configuration should be added using the ClickHouse config fi
</rabbitmq>
```
Example:
Additional configuration:
``` sql
CREATE TABLE queue (
key UInt64,
value UInt64
) ENGINE = RabbitMQ SETTINGS rabbitmq_host_port = 'localhost:5672',
rabbitmq_exchange_name = 'exchange1',
rabbitmq_format = 'JSONEachRow',
rabbitmq_num_consumers = 5;
``` xml
<rabbitmq>
<vhost>clickhouse</vhost>
</rabbitmq>
```
## Description {#description}
@ -105,6 +117,7 @@ Exchange type options:
- `consistent_hash` - Data is evenly distributed between all bound tables (where the exchange name is the same). Note that this exchange type must be enabled with RabbitMQ plugin: `rabbitmq-plugins enable rabbitmq_consistent_hash_exchange`.
Setting `rabbitmq_queue_base` may be used for the following cases:
- to let different tables share queues, so that multiple consumers could be registered for the same queues, which makes a better performance. If using `rabbitmq_num_consumers` and/or `rabbitmq_num_queues` settings, the exact match of queues is achieved in case these parameters are the same.
- to be able to restore reading from certain durable queues when not all messages were successfully consumed. To resume consumption from one specific queue - set its name in `rabbitmq_queue_base` setting and do not specify `rabbitmq_num_consumers` and `rabbitmq_num_queues` (defaults to 1). To resume consumption from all queues, which were declared for a specific table - just specify the same settings: `rabbitmq_queue_base`, `rabbitmq_num_consumers`, `rabbitmq_num_queues`. By default, queue names will be unique to tables.
- to reuse queues as they are declared durable and not auto-deleted. (Can be deleted via any of RabbitMQ CLI tools.)

4
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View File

@ -136,8 +136,7 @@ The following settings can be specified in configuration file for given endpoint
- `access_key_id` and `secret_access_key` — Optional. Specifies credentials to use with given endpoint.
- `use_environment_credentials` — Optional, default value is `false`. If set to `true`, S3 client will try to obtain credentials from environment variables and Amazon EC2 metadata for given endpoint.
- `header` — Optional, can be speficied multiple times. Adds specified HTTP header to a request to given endpoint.
This configuration also applies to S3 disks in `MergeTree` table engine family.
- `server_side_encryption_customer_key_base64` — Optional. If specified, required headers for accessing S3 objects with SSE-C encryption will be set.
Example:
@ -149,6 +148,7 @@ Example:
<!-- <secret_access_key>SECRET_ACCESS_KEY</secret_access_key> -->
<!-- <use_environment_credentials>false</use_environment_credentials> -->
<!-- <header>Authorization: Bearer SOME-TOKEN</header> -->
<!-- <server_side_encryption_customer_key_base64>BASE64-ENCODED-KEY</server_side_encryption_customer_key_base64> -->
</endpoint-name>
</s3>
```

7
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View File

@ -104,7 +104,8 @@ For a description of parameters, see the [CREATE query description](../../../sql
- `max_parts_in_total` — Maximum number of parts in all partitions.
- `max_compress_block_size` — Maximum size of blocks of uncompressed data before compressing for writing to a table. You can also specify this setting in the global settings (see [max_compress_block_size](../../../operations/settings/settings.md#max-compress-block-size) setting). The value specified when table is created overrides the global value for this setting.
- `min_compress_block_size` — Minimum size of blocks of uncompressed data required for compression when writing the next mark. You can also specify this setting in the global settings (see [min_compress_block_size](../../../operations/settings/settings.md#min-compress-block-size) setting). The value specified when table is created overrides the global value for this setting.
- `max_partitions_to_read` — Limits the maximum number of partitions that can be accessed in one query. You can also specify setting [max_partitions_to_read](../../../operations/settings/merge-tree-settings.md#max-partitions-to-read) in the global setting.
**Example of Sections Setting**
``` sql
@ -714,6 +715,7 @@ Configuration markup:
<endpoint>https://storage.yandexcloud.net/my-bucket/root-path/</endpoint>
<access_key_id>your_access_key_id</access_key_id>
<secret_access_key>your_secret_access_key</secret_access_key>
<server_side_encryption_customer_key_base64>your_base64_encoded_customer_key</server_side_encryption_customer_key_base64>
<proxy>
<uri>http://proxy1</uri>
<uri>http://proxy2</uri>
@ -749,7 +751,8 @@ Optional parameters:
- `metadata_path` — Path on local FS to store metadata files for S3. Default value is `/var/lib/clickhouse/disks/<disk_name>/`.
- `cache_enabled` — Allows to cache mark and index files on local FS. Default value is `true`.
- `cache_path` — Path on local FS where to store cached mark and index files. Default value is `/var/lib/clickhouse/disks/<disk_name>/cache/`.
- `skip_access_check` — If true disk access checks will not be performed on disk start-up. Default value is `false`.
- `skip_access_check` — If true, disk access checks will not be performed on disk start-up. Default value is `false`.
- `server_side_encryption_customer_key_base64` — If specified, required headers for accessing S3 objects with SSE-C encryption will be set.
S3 disk can be configured as `main` or `cold` storage:

2
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View File

@ -39,4 +39,4 @@ More details on [manipulating partitions](../../sql-reference/statements/alter/p
It’s rather radical to drop all data from a table, but in some cases it might be exactly what you need.
More details on [table truncation](../../sql-reference/statements/alter/partition.md#alter_drop-partition).
More details on [table truncation](../../sql-reference/statements/truncate.md).

2
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@ -644,7 +644,7 @@ If there are no replicas at the moment on replicated table creation, a new first
``` sql
CREATE TABLE tutorial.hits_replica (...)
ENGINE = ReplcatedMergeTree(
ENGINE = ReplicatedMergeTree(
'/clickhouse_perftest/tables/{shard}/hits',
'{replica}'
)

10
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View File

@ -31,8 +31,8 @@ The supported formats are:
| [JSONCompactString](#jsoncompactstring) | ✗ | ✔ |
| [JSONEachRow](#jsoneachrow) | ✔ | ✔ |
| [JSONEachRowWithProgress](#jsoneachrowwithprogress) | ✗ | ✔ |
| [JSONStringEachRow](#jsonstringeachrow) | ✔ | ✔ |
| [JSONStringEachRowWithProgress](#jsonstringeachrowwithprogress) | ✗ | ✔ |
| [JSONStringsEachRow](#jsonstringseachrow) | ✔ | ✔ |
| [JSONStringsEachRowWithProgress](#jsonstringseachrowwithprogress) | ✗ | ✔ |
| [JSONCompactEachRow](#jsoncompacteachrow) | ✔ | ✔ |
| [JSONCompactEachRowWithNamesAndTypes](#jsoncompacteachrowwithnamesandtypes) | ✔ | ✔ |
| [JSONCompactStringEachRow](#jsoncompactstringeachrow) | ✔ | ✔ |
@ -612,7 +612,7 @@ Example:
```
## JSONEachRow {#jsoneachrow}
## JSONStringEachRow {#jsonstringeachrow}
## JSONStringsEachRow {#jsonstringseachrow}
## JSONCompactEachRow {#jsoncompacteachrow}
## JSONCompactStringEachRow {#jsoncompactstringeachrow}
@ -627,9 +627,9 @@ When using these formats, ClickHouse outputs rows as separated, newline-delimite
When inserting the data, you should provide a separate JSON value for each row.
## JSONEachRowWithProgress {#jsoneachrowwithprogress}
## JSONStringEachRowWithProgress {#jsonstringeachrowwithprogress}
## JSONStringsEachRowWithProgress {#jsonstringseachrowwithprogress}
Differs from `JSONEachRow`/`JSONStringEachRow` in that ClickHouse will also yield progress information as JSON values.
Differs from `JSONEachRow`/`JSONStringsEachRow` in that ClickHouse will also yield progress information as JSON values.
```json
{"row":{"'hello'":"hello","multiply(42, number)":"0","range(5)":[0,1,2,3,4]}}

1
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View File

@ -81,6 +81,7 @@ toc_title: Adopters
| <a href="https://posthog.com/" class="favicon">PostHog</a> | Product Analytics | Main Product | — | — | [Release Notes, Oct 2020](https://posthog.com/blog/the-posthog-array-1-15-0) |
| <a href="https://postmates.com/" class="favicon">Postmates</a> | Delivery | — | — | — | [Talk in English, July 2020](https://youtu.be/GMiXCMFDMow?t=188) |
| <a href="http://www.pragma-innovation.fr/" class="favicon">Pragma Innovation</a> | Telemetry and Big Data Analysis | Main product | — | — | [Slides in English, October 2018](https://github.com/ClickHouse/clickhouse-presentations/blob/master/meetup18/4_pragma_innovation.pdf) |
| <a href="https://prana-system.com/en/" class="favicon">PRANA</a> | Industrial predictive analytics | Main product | — | — | [News (russian), Feb 2021](https://habr.com/en/news/t/541392/) |
| <a href="https://www.qingcloud.com/" class="favicon">QINGCLOUD</a> | Cloud services | Main product | — | — | [Slides in Chinese, October 2018](https://github.com/ClickHouse/clickhouse-presentations/blob/master/meetup19/4.%20Cloud%20%2B%20TSDB%20for%20ClickHouse%20张健%20QingCloud.pdf) |
| <a href="https://qrator.net" class="favicon">Qrator</a> | DDoS protection | Main product | — | — | [Blog Post, March 2019](https://blog.qrator.net/en/clickhouse-ddos-mitigation_37/) |
| <a href="https://www.rbinternational.com/" class="favicon">Raiffeisenbank</a> | Banking | Analytics | — | — | [Lecture in Russian, December 2020](https://cs.hse.ru/announcements/421965599.html) |

2
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View File

@ -5,7 +5,7 @@ toc_title: Data Backup
# Data Backup {#data-backup}
While [replication](../engines/table-engines/mergetree-family/replication.md) provides protection from hardware failures, it does not protect against human errors: accidental deletion of data, deletion of the wrong table or a table on the wrong cluster, and software bugs that result in incorrect data processing or data corruption. In many cases mistakes like these will affect all replicas. ClickHouse has built-in safeguards to prevent some types of mistakes — for example, by default [you can’t just drop tables with a MergeTree-like engine containing more than 50 Gb of data](https://github.com/ClickHouse/ClickHouse/blob/v18.14.18-stable/programs/server/config.xml#L322-L330). However, these safeguards don’t cover all possible cases and can be circumvented.
While [replication](../engines/table-engines/mergetree-family/replication.md) provides protection from hardware failures, it does not protect against human errors: accidental deletion of data, deletion of the wrong table or a table on the wrong cluster, and software bugs that result in incorrect data processing or data corruption. In many cases mistakes like these will affect all replicas. ClickHouse has built-in safeguards to prevent some types of mistakes — for example, by default [you can’t just drop tables with a MergeTree-like engine containing more than 50 Gb of data](server-configuration-parameters/settings.md#max-table-size-to-drop). However, these safeguards don’t cover all possible cases and can be circumvented.
In order to effectively mitigate possible human errors, you should carefully prepare a strategy for backing up and restoring your data **in advance**.

13
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@ -0,0 +1,13 @@
---
toc_folder_title: External User Authenticators and Directories
toc_priority: 48
toc_title: Introduction
---
# External User Authenticators and Directories {#external-authenticators}
ClickHouse supports authenticating and managing users using external services.
The following external authenticators and directories are supported:
- [LDAP](./ldap.md#external-authenticators-ldap) [Authenticator](./ldap.md#ldap-external-authenticator) and [Directory](./ldap.md#ldap-external-user-directory)

156
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@ -0,0 +1,156 @@
# LDAP {#external-authenticators-ldap}
LDAP server can be used to authenticate ClickHouse users. There are two different approaches for doing this:
- use LDAP as an external authenticator for existing users, which are defined in `users.xml` or in local access control paths
- use LDAP as an external user directory and allow locally undefined users to be authenticated if they exist on the LDAP server
For both of these approaches, an internally named LDAP server must be defined in the ClickHouse config so that other parts of config are able to refer to it.
## LDAP Server Definition {#ldap-server-definition}
To define LDAP server you must add `ldap_servers` section to the `config.xml`. For example,
```xml
<yandex>
<!- ... -->
<ldap_servers>
<my_ldap_server>
<host>localhost</host>
<port>636</port>
<bind_dn>uid={user_name},ou=users,dc=example,dc=com</bind_dn>
<verification_cooldown>300</verification_cooldown>
<enable_tls>yes</enable_tls>
<tls_minimum_protocol_version>tls1.2</tls_minimum_protocol_version>
<tls_require_cert>demand</tls_require_cert>
<tls_cert_file>/path/to/tls_cert_file</tls_cert_file>
<tls_key_file>/path/to/tls_key_file</tls_key_file>
<tls_ca_cert_file>/path/to/tls_ca_cert_file</tls_ca_cert_file>
<tls_ca_cert_dir>/path/to/tls_ca_cert_dir</tls_ca_cert_dir>
<tls_cipher_suite>ECDHE-ECDSA-AES256-GCM-SHA384:ECDHE-RSA-AES256-GCM-SHA384:AES256-GCM-SHA384</tls_cipher_suite>
</my_ldap_server>
</ldap_servers>
</yandex>
```
Note, that you can define multiple LDAP servers inside the `ldap_servers` section using distinct names.
Parameters:
- `host` - LDAP server hostname or IP, this parameter is mandatory and cannot be empty.
- `port` - LDAP server port, default is `636` if `enable_tls` is set to `true`, `389` otherwise.
- `bind_dn` - template used to construct the DN to bind to.
- The resulting DN will be constructed by replacing all `{user_name}` substrings of the
template with the actual user name during each authentication attempt.
- `verification_cooldown` - a period of time, in seconds, after a successful bind attempt,
during which the user will be assumed to be successfully authenticated for all consecutive
requests without contacting the LDAP server.
- Specify `0` (the default) to disable caching and force contacting the LDAP server for each authentication request.
- `enable_tls` - flag to trigger use of secure connection to the LDAP server.
- Specify `no` for plain text `ldap://` protocol (not recommended).
- Specify `yes` for LDAP over SSL/TLS `ldaps://` protocol (recommended, the default).
- Specify `starttls` for legacy StartTLS protocol (plain text `ldap://` protocol, upgraded to TLS).
- `tls_minimum_protocol_version` - the minimum protocol version of SSL/TLS.
- Accepted values are: `ssl2`, `ssl3`, `tls1.0`, `tls1.1`, `tls1.2` (the default).
- `tls_require_cert` - SSL/TLS peer certificate verification behavior.
- Accepted values are: `never`, `allow`, `try`, `demand` (the default).
- `tls_cert_file` - path to certificate file.
- `tls_key_file` - path to certificate key file.
- `tls_ca_cert_file` - path to CA certificate file.
- `tls_ca_cert_dir` - path to the directory containing CA certificates.
- `tls_cipher_suite` - allowed cipher suite (in OpenSSL notation).
## LDAP External Authenticator {#ldap-external-authenticator}
A remote LDAP server can be used as a method for verifying passwords for locally defined users (users defined in `users.xml` or in local access control paths). In order to achieve this, specify previously defined LDAP server name instead of `password` or similar sections in the user definition.
At each login attempt, ClickHouse will try to "bind" to the specified DN defined by the `bind_dn` parameter in the [LDAP server definition](#ldap-server-definition) using the provided credentials, and if successful, the user will be considered authenticated. This is often called a "simple bind" method.
For example,
```xml
<yandex>
<!- ... -->
<users>
<!- ... -->
<my_user>
<!- ... -->
<ldap>
<server>my_ldap_server</server>
</ldap>
</my_user>
</users>
</yandex>
```
Note, that user `my_user` refers to `my_ldap_server`. This LDAP server must be configured in the main `config.xml` file as described previously.
When SQL-driven [Access Control and Account Management](../access-rights.md#access-control) is enabled in ClickHouse, users that are authenticated by LDAP servers can also be created using the [CRATE USER](../../sql-reference/statements/create/user.md#create-user-statement) statement.
```sql
CREATE USER my_user IDENTIFIED WITH ldap_server BY 'my_ldap_server'
```
## LDAP Exernal User Directory {#ldap-external-user-directory}
In addition to the locally defined users, a remote LDAP server can be used as a source of user definitions. In order to achieve this, specify previously defined LDAP server name (see [LDAP Server Definition](#ldap-server-definition)) in the `ldap` section inside the `users_directories` section of the `config.xml` file.
At each login attempt, ClickHouse will try to find the user definition locally and authenticate it as usual, but if the user is not defined, ClickHouse will assume it exists in the external LDAP directory, and will try to "bind" to the specified DN at the LDAP server using the provided credentials. If successful, the user will be considered existing and authenticated. The user will be assigned roles from the list specified in the `roles` section. Additionally, LDAP "search" can be performed and results can be transformed and treated as role names and then be assigned to the user if the `role_mapping` section is also configured. All this implies that the SQL-driven [Access Control and Account Management](../access-rights.md#access-control) is enabled and roles are created using the [CREATE ROLE](../../sql-reference/statements/create/role.md#create-role-statement) statement.
Example (goes into `config.xml`):
```xml
<yandex>
<!- ... -->
<user_directories>
<!- ... -->
<ldap>
<server>my_ldap_server</server>
<roles>
<my_local_role1 />
<my_local_role2 />
</roles>
<role_mapping>
<base_dn>ou=groups,dc=example,dc=com</base_dn>
<scope>subtree</scope>
<search_filter>(&amp;(objectClass=groupOfNames)(member={bind_dn}))</search_filter>
<attribute>cn</attribute>
<prefix>clickhouse_</prefix>
</role_mapping>
</ldap>
</user_directories>
</yandex>
```
Note that `my_ldap_server` referred in the `ldap` section inside the `user_directories` section must be a previously
defined LDAP server that is configured in the `config.xml` (see [LDAP Server Definition](#ldap-server-definition)).
Parameters:
- `server` - one of LDAP server names defined in the `ldap_servers` config section above.
This parameter is mandatory and cannot be empty.
- `roles` - section with a list of locally defined roles that will be assigned to each user retrieved from the LDAP server.
- If no roles are specified here or assigned during role mapping (below), user will not be able
to perform any actions after authentication.
- `role_mapping` - section with LDAP search parameters and mapping rules.
- When a user authenticates, while still bound to LDAP, an LDAP search is performed using `search_filter`
and the name of the logged in user. For each entry found during that search, the value of the specified
attribute is extracted. For each attribute value that has the specified prefix, the prefix is removed,
and the rest of the value becomes the name of a local role defined in ClickHouse,
which is expected to be created beforehand by the [CREATE ROLE](../../sql-reference/statements/create/role.md#create-role-statement) statement.
- There can be multiple `role_mapping` sections defined inside the same `ldap` section. All of them will be applied.
- `base_dn` - template used to construct the base DN for the LDAP search.
- The resulting DN will be constructed by replacing all `{user_name}` and `{bind_dn}`
substrings of the template with the actual user name and bind DN during each LDAP search.
- `scope` - scope of the LDAP search.
- Accepted values are: `base`, `one_level`, `children`, `subtree` (the default).
- `search_filter` - template used to construct the search filter for the LDAP search.
- The resulting filter will be constructed by replacing all `{user_name}`, `{bind_dn}`, and `{base_dn}`
substrings of the template with the actual user name, bind DN, and base DN during each LDAP search.
- Note, that the special characters must be escaped properly in XML.
- `attribute` - attribute name whose values will be returned by the LDAP search.
- `prefix` - prefix, that will be expected to be in front of each string in the original
list of strings returned by the LDAP search. Prefix will be removed from the original
strings and resulting strings will be treated as local role names. Empty, by default.

10
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@ -29,6 +29,8 @@ Let’s look at the section of the ‘users.xml’ file that defines quotas.
<!-- Unlimited. Just collect data for the specified time interval. -->
<queries>0</queries>
<query_selects>0</query_selects>
<query_inserts>0</query_inserts>
<errors>0</errors>
<result_rows>0</result_rows>
<read_rows>0</read_rows>
@ -48,6 +50,8 @@ The resource consumption calculated for each interval is output to the server lo
<duration>3600</duration>
<queries>1000</queries>
<query_selects>100</query_selects>
<query_inserts>100</query_inserts>
<errors>100</errors>
<result_rows>1000000000</result_rows>
<read_rows>100000000000</read_rows>
@ -58,6 +62,8 @@ The resource consumption calculated for each interval is output to the server lo
<duration>86400</duration>
<queries>10000</queries>
<query_selects>10000</query_selects>
<query_inserts>10000</query_inserts>
<errors>1000</errors>
<result_rows>5000000000</result_rows>
<read_rows>500000000000</read_rows>
@ -74,6 +80,10 @@ Here are the amounts that can be restricted:
`queries` – The total number of requests.
`query_selects` – The total number of select requests.
`query_inserts` – The total number of insert requests.
`errors` – The number of queries that threw an exception.
`result_rows` – The total number of rows given as a result.

11
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@ -186,5 +186,16 @@ Possible values:
Default value: auto (number of CPU cores).
During startup ClickHouse reads all parts of all tables (reads files with metadata of parts) to build a list of all parts in memory. In some systems with a large number of parts this process can take a long time, and this time might be shortened by increasing `max_part_loading_threads` (if this process is not CPU and disk I/O bound).
## max_partitions_to_read {#max-partitions-to-read}
Limits the maximum number of partitions that can be accessed in one query.
The setting value specified when the table is created can be overridden via query-level setting.
Possible values:
- Any positive integer.
Default value: -1 (unlimited).
[Original article](https://clickhouse.tech/docs/en/operations/settings/merge_tree_settings/) <!--hide-->

68
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@ -312,7 +312,7 @@ Enables or disables parsing enum values as enum ids for TSV input format.
Possible values:
- 0 — Enum values are parsed as values.
- 1 — Enum values are parsed as enum IDs
- 1 — Enum values are parsed as enum IDs.
Default value: 0.
@ -2592,4 +2592,70 @@ Possible values:
Default value: `16`.
## opentelemetry_start_trace_probability {#opentelemetry-start-trace-probability}
Sets the probability that the ClickHouse can start a trace for executed queries (if no parent [trace context](https://www.w3.org/TR/trace-context/) is supplied).
Possible values:
- 0 — The trace for all executed queries is disabled (if no parent trace context is supplied).
- Positive floating-point number in the range [0..1]. For example, if the setting value is `0,5`, ClickHouse can start a trace on average for half of the queries.
- 1 — The trace for all executed queries is enabled.
Default value: `0`.
## optimize_on_insert {#optimize-on-insert}
Enables or disables data transformation before the insertion, as if merge was done on this block (according to table engine).
Possible values:
- 0 — Disabled.
- 1 — Enabled.
Default value: 1.
**Example**
The difference between enabled and disabled:
Query:
```sql
SET optimize_on_insert = 1;
CREATE TABLE test1 (`FirstTable` UInt32) ENGINE = ReplacingMergeTree ORDER BY FirstTable;
INSERT INTO test1 SELECT number % 2 FROM numbers(5);
SELECT * FROM test1;
SET optimize_on_insert = 0;
CREATE TABLE test2 (`SecondTable` UInt32) ENGINE = ReplacingMergeTree ORDER BY SecondTable;
INSERT INTO test2 SELECT number % 2 FROM numbers(5);
SELECT * FROM test2;
```
Result:
``` text
┌─FirstTable─┐
│ 0 │
│ 1 │
└────────────┘
┌─SecondTable─┐
│ 0 │
│ 0 │
│ 0 │
│ 1 │
│ 1 │
└─────────────┘
```
Note that this setting influences [Materialized view](../../sql-reference/statements/create/view.md#materialized) and [MaterializeMySQL](../../engines/database-engines/materialize-mysql.md) behaviour.
[Original article](https://clickhouse.tech/docs/en/operations/settings/settings/) <!-- hide -->

53
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@ -0,0 +1,53 @@
# system.opentelemetry_span_log {#system_tables-opentelemetry_span_log}
Contains information about [trace spans](https://opentracing.io/docs/overview/spans/) for executed queries.
Columns:
- `trace_id` ([UUID](../../sql-reference/data-types/uuid.md) — ID of the trace for executed query.
- `span_id` ([UInt64](../../sql-reference/data-types/int-uint.md)) — ID of the `trace span`.
- `parent_span_id` ([UInt64](../../sql-reference/data-types/int-uint.md)) — ID of the parent `trace span`.
- `operation_name` ([String](../../sql-reference/data-types/string.md)) — The name of the operation.
- `start_time_us` ([UInt64](../../sql-reference/data-types/int-uint.md)) — The start time of the `trace span` (in microseconds).
- `finish_time_us` ([UInt64](../../sql-reference/data-types/int-uint.md)) — The finish time of the `trace span` (in microseconds).
- `finish_date` ([Date](../../sql-reference/data-types/date.md)) — The finish date of the `trace span`.
- `attribute.names` ([Array](../../sql-reference/data-types/array.md)([String](../../sql-reference/data-types/string.md))) — [Attribute](https://opentelemetry.io/docs/go/instrumentation/#attributes) names depending on the `trace span`. They are filled in according to the recommendations in the [OpenTelemetry](https://opentelemetry.io/) standard.
- `attribute.values` ([Array](../../sql-reference/data-types/array.md)([String](../../sql-reference/data-types/string.md))) — Attribute values depending on the `trace span`. They are filled in according to the recommendations in the `OpenTelemetry` standard.
**Example**
Query:
``` sql
SELECT * FROM system.opentelemetry_span_log LIMIT 1 FORMAT Vertical;
```
Result:
``` text
Row 1:
──────
trace_id: cdab0847-0d62-61d5-4d38-dd65b19a1914
span_id: 701487461015578150
parent_span_id: 2991972114672045096
operation_name: DB::Block DB::InterpreterSelectQuery::getSampleBlockImpl()
start_time_us: 1612374594529090
finish_time_us: 1612374594529108
finish_date: 2021-02-03
attribute.names: []
attribute.values: []
```
**See Also**
- [OpenTelemetry](../../operations/opentelemetry.md)
[Original article](https://clickhouse.tech/docs/en/operations/system_tables/opentelemetry_span_log) <!--hide-->

68
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@ -6,29 +6,65 @@ This table contains information about events that occurred with [data parts](../
The `system.part_log` table contains the following columns:
- `event_type` (Enum) — Type of the event that occurred with the data part. Can have one of the following values:
- `query_id` ([String](../../sql-reference/data-types/string.md)) — Identifier of the `INSERT` query that created this data part.
- `event_type` ([Enum8](../../sql-reference/data-types/enum.md)) — Type of the event that occurred with the data part. Can have one of the following values:
- `NEW_PART` — Inserting of a new data part.
- `MERGE_PARTS` — Merging of data parts.
- `DOWNLOAD_PART` — Downloading a data part.
- `REMOVE_PART` — Removing or detaching a data part using [DETACH PARTITION](../../sql-reference/statements/alter/partition.md#alter_detach-partition).
- `MUTATE_PART` — Mutating of a data part.
- `MOVE_PART` — Moving the data part from the one disk to another one.
- `event_date` (Date) — Event date.
- `event_time` (DateTime) — Event time.
- `duration_ms` (UInt64) — Duration.
- `database` (String) — Name of the database the data part is in.
- `table` (String) — Name of the table the data part is in.
- `part_name` (String) — Name of the data part.
- `partition_id` (String) — ID of the partition that the data part was inserted to. The column takes the ‘all’ value if the partitioning is by `tuple()`.
- `rows` (UInt64) — The number of rows in the data part.
- `size_in_bytes` (UInt64) — Size of the data part in bytes.
- `merged_from` (Array(String)) — An array of names of the parts which the current part was made up from (after the merge).
- `bytes_uncompressed` (UInt64) — Size of uncompressed bytes.
- `read_rows` (UInt64) — The number of rows was read during the merge.
- `read_bytes` (UInt64) — The number of bytes was read during the merge.
- `error` (UInt16) — The code number of the occurred error.
- `exception` (String) — Text message of the occurred error.
- `event_date` ([Date](../../sql-reference/data-types/date.md)) — Event date.
- `event_time` ([DateTime](../../sql-reference/data-types/datetime.md)) — Event time.
- `event_time_microseconds` ([DateTime64](../../sql-reference/data-types/datetime64.md)) — Event time with microseconds precision.
- `duration_ms` ([UInt64](../../sql-reference/data-types/int-uint.md)) — Duration.
- `database` ([String](../../sql-reference/data-types/string.md)) — Name of the database the data part is in.
- `table` ([String](../../sql-reference/data-types/string.md)) — Name of the table the data part is in.
- `part_name` ([String](../../sql-reference/data-types/string.md)) — Name of the data part.
- `partition_id` ([String](../../sql-reference/data-types/string.md)) — ID of the partition that the data part was inserted to. The column takes the `all` value if the partitioning is by `tuple()`.
- `path_on_disk` ([String](../../sql-reference/data-types/string.md)) — Absolute path to the folder with data part files.
- `rows` ([UInt64](../../sql-reference/data-types/int-uint.md)) — The number of rows in the data part.
- `size_in_bytes` ([UInt64](../../sql-reference/data-types/int-uint.md)) — Size of the data part in bytes.
- `merged_from` ([Array(String)](../../sql-reference/data-types/array.md)) — An array of names of the parts which the current part was made up from (after the merge).
- `bytes_uncompressed` ([UInt64](../../sql-reference/data-types/int-uint.md)) — Size of uncompressed bytes.
- `read_rows` ([UInt64](../../sql-reference/data-types/int-uint.md)) — The number of rows was read during the merge.
- `read_bytes` ([UInt64](../../sql-reference/data-types/int-uint.md)) — The number of bytes was read during the merge.
- `peak_memory_usage` ([Int64](../../sql-reference/data-types/int-uint.md)) — The maximum difference between the amount of allocated and freed memory in context of this thread.
- `error` ([UInt16](../../sql-reference/data-types/int-uint.md)) — The code number of the occurred error.
- `exception` ([String](../../sql-reference/data-types/string.md)) — Text message of the occurred error.
The `system.part_log` table is created after the first inserting data to the `MergeTree` table.
**Example**
``` sql
SELECT * FROM system.part_log LIMIT 1 FORMAT Vertical;
```
``` text
Row 1:
──────
query_id: 983ad9c7-28d5-4ae1-844e-603116b7de31
event_type: NewPart
event_date: 2021-02-02
event_time: 2021-02-02 11:14:28
event_time_microseconds: 2021-02-02 11:14:28.861919
duration_ms: 35
database: default
table: log_mt_2
part_name: all_1_1_0
partition_id: all
path_on_disk: db/data/default/log_mt_2/all_1_1_0/
rows: 115418
size_in_bytes: 1074311
merged_from: []
bytes_uncompressed: 0
read_rows: 0
read_bytes: 0
peak_memory_usage: 0
error: 0
exception:
```
[Original article](https://clickhouse.tech/docs/en/operations/system_tables/part_log) <!--hide-->

2
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@ -9,6 +9,8 @@ Columns:
- `0` — Interval is not randomized.
- `1` — Interval is randomized.
- `max_queries` ([Nullable](../../sql-reference/data-types/nullable.md)([UInt64](../../sql-reference/data-types/int-uint.md))) — Maximum number of queries.
- `max_query_selects` ([Nullable](../../sql-reference/data-types/nullable.md)([UInt64](../../sql-reference/data-types/int-uint.md))) — Maximum number of select queries.
- `max_query_inserts` ([Nullable](../../sql-reference/data-types/nullable.md)([UInt64](../../sql-reference/data-types/int-uint.md))) — Maximum number of insert queries.
- `max_errors` ([Nullable](../../sql-reference/data-types/nullable.md)([UInt64](../../sql-reference/data-types/int-uint.md))) — Maximum number of errors.
- `max_result_rows` ([Nullable](../../sql-reference/data-types/nullable.md)([UInt64](../../sql-reference/data-types/int-uint.md))) — Maximum number of result rows.
- `max_result_bytes` ([Nullable](../../sql-reference/data-types/nullable.md)([UInt64](../../sql-reference/data-types/int-uint.md))) — Maximum number of RAM volume in bytes used to store a queries result.

2
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@ -9,6 +9,8 @@ Columns:
- `end_time`([Nullable](../../sql-reference/data-types/nullable.md)([DateTime](../../sql-reference/data-types/datetime.md))) — End time for calculating resource consumption.
- `duration` ([Nullable](../../sql-reference/data-types/nullable.md)([UInt64](../../sql-reference/data-types/int-uint.md))) — Length of the time interval for calculating resource consumption, in seconds.
- `queries` ([Nullable](../../sql-reference/data-types/nullable.md)([UInt64](../../sql-reference/data-types/int-uint.md))) — The total number of requests on this interval.
- `query_selects` ([Nullable](../../sql-reference/data-types/nullable.md)([UInt64](../../sql-reference/data-types/int-uint.md))) — The total number of select requests on this interval.
- `query_inserts` ([Nullable](../../sql-reference/data-types/nullable.md)([UInt64](../../sql-reference/data-types/int-uint.md))) — The total number of insert requests on this interval.
- `max_queries` ([Nullable](../../sql-reference/data-types/nullable.md)([UInt64](../../sql-reference/data-types/int-uint.md))) — Maximum number of requests.
- `errors` ([Nullable](../../sql-reference/data-types/nullable.md)([UInt64](../../sql-reference/data-types/int-uint.md))) — The number of queries that threw an exception.
- `max_errors` ([Nullable](../../sql-reference/data-types/nullable.md)([UInt64](../../sql-reference/data-types/int-uint.md))) — Maximum number of errors.

4
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@ -11,6 +11,10 @@ Columns:
- `duration` ([Nullable](../../sql-reference/data-types/nullable.md)([UInt32](../../sql-reference/data-types/int-uint.md))) — Length of the time interval for calculating resource consumption, in seconds.
- `queries` ([Nullable](../../sql-reference/data-types/nullable.md)([UInt64](../../sql-reference/data-types/int-uint.md))) — The total number of requests in this interval.
- `max_queries` ([Nullable](../../sql-reference/data-types/nullable.md)([UInt64](../../sql-reference/data-types/int-uint.md))) — Maximum number of requests.
- `query_selects` ([Nullable](../../sql-reference/data-types/nullable.md)([UInt64](../../sql-reference/data-types/int-uint.md))) — The total number of select requests in this interval.
- `max_query_selects` ([Nullable](../../sql-reference/data-types/nullable.md)([UInt64](../../sql-reference/data-types/int-uint.md))) — Maximum number of select requests.
- `query_inserts` ([Nullable](../../sql-reference/data-types/nullable.md)([UInt64](../../sql-reference/data-types/int-uint.md))) — The total number of insert requests in this interval.
- `max_query_inserts` ([Nullable](../../sql-reference/data-types/nullable.md)([UInt64](../../sql-reference/data-types/int-uint.md))) — Maximum number of insert requests.
- `errors` ([Nullable](../../sql-reference/data-types/nullable.md)([UInt64](../../sql-reference/data-types/int-uint.md))) — The number of queries that threw an exception.
- `max_errors` ([Nullable](../../sql-reference/data-types/nullable.md)([UInt64](../../sql-reference/data-types/int-uint.md))) — Maximum number of errors.
- `result_rows` ([Nullable](../../sql-reference/data-types/nullable.md)([UInt64](../../sql-reference/data-types/int-uint.md))) — The total number of rows given as a result.

6
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@ -1,12 +1,16 @@
# system.zookeeper {#system-zookeeper}
The table does not exist if ZooKeeper is not configured. Allows reading data from the ZooKeeper cluster defined in the config.
The query must have a ‘path’ equality condition in the WHERE clause. This is the path in ZooKeeper for the children that you want to get data for.
The query must either have a ‘path =’ condition or a `path IN` condition set with the `WHERE` clause as shown below. This corresponds to the path of the children in ZooKeeper that you want to get data for.
The query `SELECT * FROM system.zookeeper WHERE path = '/clickhouse'` outputs data for all children on the `/clickhouse` node.
To output data for all root nodes, write path = ‘/’.
If the path specified in ‘path’ doesn’t exist, an exception will be thrown.
The query `SELECT * FROM system.zookeeper WHERE path IN ('/', '/clickhouse')` outputs data for all children on the `/` and `/clickhouse` node.
If in the specified ‘path’ collection has doesn't exist path, an exception will be thrown.
It can be used to do a batch of ZooKeeper path queries.
Columns:
- `name` (String) — The name of the node.

20
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@ -1,9 +1,9 @@
---
toc_priority: 47
toc_title: ClickHouse Update
toc_title: ClickHouse Upgrade
---
# ClickHouse Update {#clickhouse-update}
# ClickHouse Upgrade {#clickhouse-upgrade}
If ClickHouse was installed from `deb` packages, execute the following commands on the server:
@ -16,3 +16,19 @@ $ sudo service clickhouse-server restart
If you installed ClickHouse using something other than the recommended `deb` packages, use the appropriate update method.
ClickHouse does not support a distributed update. The operation should be performed consecutively on each separate server. Do not update all the servers on a cluster simultaneously, or the cluster will be unavailable for some time.
The upgrade of older version of ClickHouse to specific version:
As an example:
`xx.yy.a.b` is a current stable version. The latest stable version could be found [here](https://github.com/ClickHouse/ClickHouse/releases)
```bash
$ sudo apt-get update
$ sudo apt-get install clickhouse-server=xx.yy.a.b clickhouse-client=xx.yy.a.b clickhouse-common-static=xx.yy.a.b
$ sudo service clickhouse-server restart
```

6
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@ -72,7 +72,7 @@ If an aggregate function doesn’t have input values, with this combinator it re
<aggFunction>OrDefault(x)
```
**Parameters**
**Arguments**
- `x` — Aggregate function parameters.
@ -132,7 +132,7 @@ This combinator converts a result of an aggregate function to the [Nullable](../
<aggFunction>OrNull(x)
```
**Parameters**
**Arguments**
- `x` — Aggregate function parameters.
@ -189,7 +189,7 @@ Lets you divide data into groups, and then separately aggregates the data in tho
<aggFunction>Resample(start, end, step)(<aggFunction_params>, resampling_key)
```
**Parameters**
**Arguments**
- `start` — Starting value of the whole required interval for `resampling_key` values.
- `stop` — Ending value of the whole required interval for `resampling_key` values. The whole interval doesn’t include the `stop` value `[start, stop)`.

32
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@ -17,10 +17,13 @@ histogram(number_of_bins)(values)
The functions uses [A Streaming Parallel Decision Tree Algorithm](http://jmlr.org/papers/volume11/ben-haim10a/ben-haim10a.pdf). The borders of histogram bins are adjusted as new data enters a function. In common case, the widths of bins are not equal.
**Arguments**
`values` — [Expression](../../sql-reference/syntax.md#syntax-expressions) resulting in input values.
**Parameters**
`number_of_bins` — Upper limit for the number of bins in the histogram. The function automatically calculates the number of bins. It tries to reach the specified number of bins, but if it fails, it uses fewer bins.
`values` — [Expression](../../sql-reference/syntax.md#syntax-expressions) resulting in input values.
**Returned values**
@ -89,14 +92,16 @@ sequenceMatch(pattern)(timestamp, cond1, cond2, ...)
!!! warning "Warning"
Events that occur at the same second may lay in the sequence in an undefined order affecting the result.
**Parameters**
- `pattern` — Pattern string. See [Pattern syntax](#sequence-function-pattern-syntax).
**Arguments**
- `timestamp` — Column considered to contain time data. Typical data types are `Date` and `DateTime`. You can also use any of the supported [UInt](../../sql-reference/data-types/int-uint.md) data types.
- `cond1`, `cond2` — Conditions that describe the chain of events. Data type: `UInt8`. You can pass up to 32 condition arguments. The function takes only the events described in these conditions into account. If the sequence contains data that isn’t described in a condition, the function skips them.
**Parameters**
- `pattern` — Pattern string. See [Pattern syntax](#sequence-function-pattern-syntax).
**Returned values**
- 1, if the pattern is matched.
@ -176,14 +181,16 @@ Counts the number of event chains that matched the pattern. The function searche
sequenceCount(pattern)(timestamp, cond1, cond2, ...)
```
**Parameters**
- `pattern` — Pattern string. See [Pattern syntax](#sequence-function-pattern-syntax).
**Arguments**
- `timestamp` — Column considered to contain time data. Typical data types are `Date` and `DateTime`. You can also use any of the supported [UInt](../../sql-reference/data-types/int-uint.md) data types.
- `cond1`, `cond2` — Conditions that describe the chain of events. Data type: `UInt8`. You can pass up to 32 condition arguments. The function takes only the events described in these conditions into account. If the sequence contains data that isn’t described in a condition, the function skips them.
**Parameters**
- `pattern` — Pattern string. See [Pattern syntax](#sequence-function-pattern-syntax).
**Returned values**
- Number of non-overlapping event chains that are matched.
@ -239,13 +246,16 @@ The function works according to the algorithm:
windowFunnel(window, [mode])(timestamp, cond1, cond2, ..., condN)
```
**Arguments**
- `timestamp` — Name of the column containing the timestamp. Data types supported: [Date](../../sql-reference/data-types/date.md), [DateTime](../../sql-reference/data-types/datetime.md#data_type-datetime) and other unsigned integer types (note that even though timestamp supports the `UInt64` type, it’s value can’t exceed the Int64 maximum, which is 2^63 - 1).
- `cond` — Conditions or data describing the chain of events. [UInt8](../../sql-reference/data-types/int-uint.md).
**Parameters**
- `window` — Length of the sliding window. The unit of `window` depends on the timestamp itself and varies. Determined using the expression `timestamp of cond2 <= timestamp of cond1 + window`.
- `mode` - It is an optional argument.
- `mode` - It is an optional parameter.
- `'strict'` - When the `'strict'` is set, the windowFunnel() applies conditions only for the unique values.
- `timestamp` — Name of the column containing the timestamp. Data types supported: [Date](../../sql-reference/data-types/date.md), [DateTime](../../sql-reference/data-types/datetime.md#data_type-datetime) and other unsigned integer types (note that even though timestamp supports the `UInt64` type, it’s value can’t exceed the Int64 maximum, which is 2^63 - 1).
- `cond` — Conditions or data describing the chain of events. [UInt8](../../sql-reference/data-types/int-uint.md).
**Returned value**
@ -324,7 +334,7 @@ The conditions, except the first, apply in pairs: the result of the second will
retention(cond1, cond2, ..., cond32);
```
**Parameters**
**Arguments**
- `cond` — an expression that returns a `UInt8` result (1 or 0).

45
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@ -4,13 +4,42 @@ toc_priority: 106
# argMax {#agg-function-argmax}
Syntax: `argMax(arg, val)` or `argMax(tuple(arg, val))`
Calculates the `arg` value for a maximum `val` value. If there are several different values of `arg` for maximum values of `val`, returns the first of these values encountered.
Calculates the `arg` value for a maximum `val` value. If there are several different values of `arg` for maximum values of `val`, the first of these values encountered is output.
Tuple version of this function will return the tuple with the maximum `val` value. It is convenient for use with [SimpleAggregateFunction](../../../sql-reference/data-types/simpleaggregatefunction.md).
Tuple version of this function will return the tuple with the maximum `val` value. It is convinient for use with `SimpleAggregateFunction`.
**Syntax**
**Example:**
``` sql
argMax(arg, val)
```
or
``` sql
argMax(tuple(arg, val))
```
**Arguments**
- `arg` — Argument.
- `val` — Value.
**Returned value**
- `arg` value that corresponds to maximum `val` value.
Type: matches `arg` type.
For tuple in the input:
- Tuple `(arg, val)`, where `val` is the maximum value and `arg` is a corresponding value.
Type: [Tuple](../../../sql-reference/data-types/tuple.md).
**Example**
Input table:
``` text
┌─user─────┬─salary─┐
@ -20,12 +49,18 @@ Tuple version of this function will return the tuple with the maximum `val` valu
└──────────┴────────┘
```
Query:
``` sql
SELECT argMax(user, salary), argMax(tuple(user, salary)) FROM salary
SELECT argMax(user, salary), argMax(tuple(user, salary)) FROM salary;
```
Result:
``` text
┌─argMax(user, salary)─┬─argMax(tuple(user, salary))─┐
│ director │ ('director',5000) │
└──────────────────────┴─────────────────────────────┘
```
[Original article](https://clickhouse.tech/docs/en/sql-reference/aggregate-functions/reference/argmax/) <!--hide-->

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@ -4,13 +4,42 @@ toc_priority: 105
# argMin {#agg-function-argmin}
Syntax: `argMin(arg, val)` or `argMin(tuple(arg, val))`
Calculates the `arg` value for a minimum `val` value. If there are several different values of `arg` for minimum values of `val`, returns the first of these values encountered.
Calculates the `arg` value for a minimal `val` value. If there are several different values of `arg` for minimal values of `val`, the first of these values encountered is output.
Tuple version of this function will return the tuple with the minimum `val` value. It is convenient for use with [SimpleAggregateFunction](../../../sql-reference/data-types/simpleaggregatefunction.md).
Tuple version of this function will return the tuple with the minimal `val` value. It is convinient for use with `SimpleAggregateFunction`.
**Syntax**
**Example:**
``` sql
argMin(arg, val)
```
or
``` sql
argMin(tuple(arg, val))
```
**Arguments**
- `arg` — Argument.
- `val` — Value.
**Returned value**
- `arg` value that corresponds to minimum `val` value.
Type: matches `arg` type.
For tuple in the input:
- Tuple `(arg, val)`, where `val` is the minimum value and `arg` is a corresponding value.
Type: [Tuple](../../../sql-reference/data-types/tuple.md).
**Example**
Input table:
``` text
┌─user─────┬─salary─┐
@ -20,12 +49,18 @@ Tuple version of this function will return the tuple with the minimal `val` valu
└──────────┴────────┘
```
Query:
``` sql
SELECT argMin(user, salary), argMin(tuple(user, salary)) FROM salary
SELECT argMin(user, salary), argMin(tuple(user, salary)) FROM salary;
```
Result:
``` text
┌─argMin(user, salary)─┬─argMin(tuple(user, salary))─┐
│ worker │ ('worker',1000) │
└──────────────────────┴─────────────────────────────┘
```
[Original article](https://clickhouse.tech/docs/en/sql-reference/aggregate-functions/reference/argmin/) <!--hide-->

2
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@ -12,7 +12,7 @@ Calculates the arithmetic mean.
avgWeighted(x)
```
**Parameter**
**Arguments**
- `x` — Values.

2
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@ -12,7 +12,7 @@ Calculates the [weighted arithmetic mean](https://en.wikipedia.org/wiki/Weighted
avgWeighted(x, weight)
```
**Parameters**
**Arguments**
- `x` — Values.
- `weight` — Weights of the values.

2
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@ -10,7 +10,7 @@ ClickHouse supports the following syntaxes for `count`:
- `count(expr)` or `COUNT(DISTINCT expr)`.
- `count()` or `COUNT(*)`. The `count()` syntax is ClickHouse-specific.
**Parameters**
**Arguments**
The function can take:

19
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@ -0,0 +1,19 @@
---
toc_priority: 141
---
# deltaSum {#agg_functions-deltasum}
Syntax: `deltaSum(value)`
Adds the differences between consecutive rows. If the difference is negative, it is ignored.
`value` must be some integer or floating point type.
Example:
```sql
select deltaSum(arrayJoin([1, 2, 3])); -- => 2
select deltaSum(arrayJoin([1, 2, 3, 0, 3, 4, 2, 3])); -- => 7
select deltaSum(arrayJoin([2.25, 3, 4.5])); -- => 2.25
```

2
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@ -17,7 +17,7 @@ If in one query several values are inserted into the same position, the function
- If a query is executed in a single thread, the first one of the inserted values is used.
- If a query is executed in multiple threads, the resulting value is an undetermined one of the inserted values.
**Parameters**
**Arguments**
- `x` — Value to be inserted. [Expression](../../../sql-reference/syntax.md#syntax-expressions) resulting in one of the [supported data types](../../../sql-reference/data-types/index.md).
- `pos` — Position at which the specified element `x` is to be inserted. Index numbering in the array starts from zero. [UInt32](../../../sql-reference/data-types/int-uint.md#uint-ranges).

2
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@ -13,7 +13,7 @@ groupArrayMovingAvg(window_size)(numbers_for_summing)
The function can take the window size as a parameter. If left unspecified, the function takes the window size equal to the number of rows in the column.
**Parameters**
**Arguments**
- `numbers_for_summing` — [Expression](../../../sql-reference/syntax.md#syntax-expressions) resulting in a numeric data type value.
- `window_size` — Size of the calculation window.

2
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@ -13,7 +13,7 @@ groupArrayMovingSum(window_size)(numbers_for_summing)
The function can take the window size as a parameter. If left unspecified, the function takes the window size equal to the number of rows in the column.
**Parameters**
**Arguments**
- `numbers_for_summing` — [Expression](../../../sql-reference/syntax.md#syntax-expressions) resulting in a numeric data type value.
- `window_size` — Size of the calculation window.

2
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@ -12,7 +12,7 @@ Creates an array of sample argument values. The size of the resulting array is l
groupArraySample(max_size[, seed])(x)
```
**Parameters**
**Arguments**
- `max_size` — Maximum size of the resulting array. [UInt64](../../data-types/int-uint.md).
- `seed` — Seed for the random number generator. Optional. [UInt64](../../data-types/int-uint.md). Default value: `123456`.

2
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@ -10,7 +10,7 @@ Applies bitwise `AND` for series of numbers.
groupBitAnd(expr)
```
**Parameters**
**Arguments**
`expr` – An expression that results in `UInt*` type.

2
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@ -10,7 +10,7 @@ Bitmap or Aggregate calculations from a unsigned integer column, return cardinal
groupBitmap(expr)
```
**Parameters**
**Arguments**
`expr` – An expression that results in `UInt*` type.

2
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@ -10,7 +10,7 @@ Calculations the AND of a bitmap column, return cardinality of type UInt64, if a
groupBitmapAnd(expr)
```
**Parameters**
**Arguments**
`expr` – An expression that results in `AggregateFunction(groupBitmap, UInt*)` type.

2
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@ -10,7 +10,7 @@ Calculations the OR of a bitmap column, return cardinality of type UInt64, if ad
groupBitmapOr(expr)
```
**Parameters**
**Arguments**
`expr` – An expression that results in `AggregateFunction(groupBitmap, UInt*)` type.

2
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@ -10,7 +10,7 @@ Calculations the XOR of a bitmap column, return cardinality of type UInt64, if a
groupBitmapOr(expr)
```
**Parameters**
**Arguments**
`expr` – An expression that results in `AggregateFunction(groupBitmap, UInt*)` type.

2
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@ -10,7 +10,7 @@ Applies bitwise `OR` for series of numbers.
groupBitOr(expr)
```
**Parameters**
**Arguments**
`expr` – An expression that results in `UInt*` type.

2
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@ -10,7 +10,7 @@ Applies bitwise `XOR` for series of numbers.
groupBitXor(expr)
```
**Parameters**
**Arguments**
`expr` – An expression that results in `UInt*` type.

2
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@ -13,7 +13,7 @@ Use it for tests or to process columns of types `AggregateFunction` and `Aggrega
initializeAggregation (aggregate_function, column_1, column_2);
```
**Parameters**
**Arguments**
- `aggregate_function` — Name of the aggregation function. The state of this function — the creating one. [String](../../../sql-reference/data-types/string.md#string).
- `column_n` — The column to translate it into the function as it's argument. [String](../../../sql-reference/data-types/string.md#string).

2
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@ -10,7 +10,7 @@ Computes the [kurtosis](https://en.wikipedia.org/wiki/Kurtosis) of a sequence.
kurtPop(expr)
```
**Parameters**
**Arguments**
`expr` — [Expression](../../../sql-reference/syntax.md#syntax-expressions) returning a number.

2
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@ -12,7 +12,7 @@ It represents an unbiased estimate of the kurtosis of a random variable if passe
kurtSamp(expr)
```
**Parameters**
**Arguments**
`expr` — [Expression](../../../sql-reference/syntax.md#syntax-expressions) returning a number.

74
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@ -0,0 +1,74 @@
---
toc_priority: 310
toc_title: mannWhitneyUTest
---
# mannWhitneyUTest {#mannwhitneyutest}
Applies the Mann-Whitney rank test to samples from two populations.
**Syntax**
``` sql
mannWhitneyUTest[(alternative[, continuity_correction])](sample_data, sample_index)
```
Values of both samples are in the `sample_data` column. If `sample_index` equals to 0 then the value in that row belongs to the sample from the first population. Otherwise it belongs to the sample from the second population.
The null hypothesis is that two populations are stochastically equal. Also one-sided hypothesises can be tested. This test does not assume that data have normal distribution.
**Arguments**
- `sample_data` — sample data. [Integer](../../../sql-reference/data-types/int-uint.md), [Float](../../../sql-reference/data-types/float.md) or [Decimal](../../../sql-reference/data-types/decimal.md).
- `sample_index` — sample index. [Integer](../../../sql-reference/data-types/int-uint.md).
**Parameters**
- `alternative` — alternative hypothesis. (Optional, default: `'two-sided'`.) [String](../../../sql-reference/data-types/string.md).
- `'two-sided'`;
- `'greater'`;
- `'less'`.
- `continuity_correction` - if not 0 then continuity correction in the normal approximation for the p-value is applied. (Optional, default: 1.) [UInt64](../../../sql-reference/data-types/int-uint.md).
**Returned values**
[Tuple](../../../sql-reference/data-types/tuple.md) with two elements:
- calculated U-statistic. [Float64](../../../sql-reference/data-types/float.md).
- calculated p-value. [Float64](../../../sql-reference/data-types/float.md).
**Example**
Input table:
``` text
┌─sample_data─┬─sample_index─┐
│ 10 │ 0 │
│ 11 │ 0 │
│ 12 │ 0 │
│ 1 │ 1 │
│ 2 │ 1 │
│ 3 │ 1 │
└─────────────┴──────────────┘
```
Query:
``` sql
SELECT mannWhitneyUTest('greater')(sample_data, sample_index) FROM mww_ttest;
```
Result:
``` text
┌─mannWhitneyUTest('greater')(sample_data, sample_index)─┐
│ (9,0.04042779918503192) │
└────────────────────────────────────────────────────────┘
```
**See Also**
- [Mann–Whitney U test](https://en.wikipedia.org/wiki/Mann%E2%80%93Whitney_U_test)
- [Stochastic ordering](https://en.wikipedia.org/wiki/Stochastic_ordering)
[Original article](https://clickhouse.tech/docs/en/sql-reference/aggregate-functions/reference/mannwhitneyutest/) <!--hide-->

2
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@ -18,7 +18,7 @@ quantile(level)(expr)
Alias: `median`.
**Parameters**
**Arguments**
- `level` — Level of quantile. Optional parameter. Constant floating-point number from 0 to 1. We recommend using a `level` value in the range of `[0.01, 0.99]`. Default value: 0.5. At `level=0.5` the function calculates [median](https://en.wikipedia.org/wiki/Median).
- `expr` — Expression over the column values resulting in numeric [data types](../../../sql-reference/data-types/index.md#data_types), [Date](../../../sql-reference/data-types/date.md) or [DateTime](../../../sql-reference/data-types/datetime.md).

2
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@ -18,7 +18,7 @@ quantileDeterministic(level)(expr, determinator)
Alias: `medianDeterministic`.
**Parameters**
**Arguments**
- `level` — Level of quantile. Optional parameter. Constant floating-point number from 0 to 1. We recommend using a `level` value in the range of `[0.01, 0.99]`. Default value: 0.5. At `level=0.5` the function calculates [median](https://en.wikipedia.org/wiki/Median).
- `expr` — Expression over the column values resulting in numeric [data types](../../../sql-reference/data-types/index.md#data_types), [Date](../../../sql-reference/data-types/date.md) or [DateTime](../../../sql-reference/data-types/datetime.md).

6
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@ -18,7 +18,7 @@ quantileExact(level)(expr)
Alias: `medianExact`.
**Parameters**
**Arguments**
- `level` — Level of quantile. Optional parameter. Constant floating-point number from 0 to 1. We recommend using a `level` value in the range of `[0.01, 0.99]`. Default value: 0.5. At `level=0.5` the function calculates [median](https://en.wikipedia.org/wiki/Median).
- `expr` — Expression over the column values resulting in numeric [data types](../../../sql-reference/data-types/index.md#data_types), [Date](../../../sql-reference/data-types/date.md) or [DateTime](../../../sql-reference/data-types/datetime.md).
@ -77,7 +77,7 @@ quantileExact(level)(expr)
Alias: `medianExactLow`.
**Parameters**
**Arguments**
- `level` — Level of quantile. Optional parameter. Constant floating-point number from 0 to 1. We recommend using a `level` value in the range of `[0.01, 0.99]`. Default value: 0.5. At `level=0.5` the function calculates [median](https://en.wikipedia.org/wiki/Median).
- `expr` — Expression over the column values resulting in numeric [data types](../../../sql-reference/data-types/index.md#data_types), [Date](../../../sql-reference/data-types/date.md) or [DateTime](../../../sql-reference/data-types/datetime.md).
@ -128,7 +128,7 @@ quantileExactHigh(level)(expr)
Alias: `medianExactHigh`.
**Parameters**
**Arguments**
- `level` — Level of quantile. Optional parameter. Constant floating-point number from 0 to 1. We recommend using a `level` value in the range of `[0.01, 0.99]`. Default value: 0.5. At `level=0.5` the function calculates [median](https://en.wikipedia.org/wiki/Median).
- `expr` — Expression over the column values resulting in numeric [data types](../../../sql-reference/data-types/index.md#data_types), [Date](../../../sql-reference/data-types/date.md) or [DateTime](../../../sql-reference/data-types/datetime.md).

2
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@ -18,7 +18,7 @@ quantileExactWeighted(level)(expr, weight)
Alias: `medianExactWeighted`.
**Parameters**
**Arguments**
- `level` — Level of quantile. Optional parameter. Constant floating-point number from 0 to 1. We recommend using a `level` value in the range of `[0.01, 0.99]`. Default value: 0.5. At `level=0.5` the function calculates [median](https://en.wikipedia.org/wiki/Median).
- `expr` — Expression over the column values resulting in numeric [data types](../../../sql-reference/data-types/index.md#data_types), [Date](../../../sql-reference/data-types/date.md) or [DateTime](../../../sql-reference/data-types/datetime.md).

2
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@ -20,7 +20,7 @@ quantileTDigest(level)(expr)
Alias: `medianTDigest`.
**Parameters**
**Arguments**
- `level` — Level of quantile. Optional parameter. Constant floating-point number from 0 to 1. We recommend using a `level` value in the range of `[0.01, 0.99]`. Default value: 0.5. At `level=0.5` the function calculates [median](https://en.wikipedia.org/wiki/Median).
- `expr` — Expression over the column values resulting in numeric [data types](../../../sql-reference/data-types/index.md#data_types), [Date](../../../sql-reference/data-types/date.md) or [DateTime](../../../sql-reference/data-types/datetime.md).

2
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@ -20,7 +20,7 @@ quantileTDigest(level)(expr)
Alias: `medianTDigest`.
**Parameters**
**Arguments**
- `level` — Level of quantile. Optional parameter. Constant floating-point number from 0 to 1. We recommend using a `level` value in the range of `[0.01, 0.99]`. Default value: 0.5. At `level=0.5` the function calculates [median](https://en.wikipedia.org/wiki/Median).
- `expr` — Expression over the column values resulting in numeric [data types](../../../sql-reference/data-types/index.md#data_types), [Date](../../../sql-reference/data-types/date.md) or [DateTime](../../../sql-reference/data-types/datetime.md).

2
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@ -18,7 +18,7 @@ quantileTiming(level)(expr)
Alias: `medianTiming`.
**Parameters**
**Arguments**
- `level` — Level of quantile. Optional parameter. Constant floating-point number from 0 to 1. We recommend using a `level` value in the range of `[0.01, 0.99]`. Default value: 0.5. At `level=0.5` the function calculates [median](https://en.wikipedia.org/wiki/Median).

2
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@ -18,7 +18,7 @@ quantileTimingWeighted(level)(expr, weight)
Alias: `medianTimingWeighted`.
**Parameters**
**Arguments**
- `level` — Level of quantile. Optional parameter. Constant floating-point number from 0 to 1. We recommend using a `level` value in the range of `[0.01, 0.99]`. Default value: 0.5. At `level=0.5` the function calculates [median](https://en.wikipedia.org/wiki/Median).

2
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@ -8,7 +8,7 @@ Computes a rank correlation coefficient.
rankCorr(x, y)
```
**Parameters**
**Arguments**
- `x` — Arbitrary value. [Float32](../../../sql-reference/data-types/float.md#float32-float64) or [Float64](../../../sql-reference/data-types/float.md#float32-float64).
- `y` — Arbitrary value. [Float32](../../../sql-reference/data-types/float.md#float32-float64) or [Float64](../../../sql-reference/data-types/float.md#float32-float64).

2
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@ -10,7 +10,7 @@ Computes the [skewness](https://en.wikipedia.org/wiki/Skewness) of a sequence.
skewPop(expr)
```
**Parameters**
**Arguments**
`expr` — [Expression](../../../sql-reference/syntax.md#syntax-expressions) returning a number.

2
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@ -12,7 +12,7 @@ It represents an unbiased estimate of the skewness of a random variable if passe
skewSamp(expr)
```
**Parameters**
**Arguments**
`expr` — [Expression](../../../sql-reference/syntax.md#syntax-expressions) returning a number.

66
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@ -0,0 +1,66 @@
---
toc_priority: 300
toc_title: studentTTest
---
# studentTTest {#studentttest}
Applies Student's t-test to samples from two populations.
**Syntax**
``` sql
studentTTest(sample_data, sample_index)
```
Values of both samples are in the `sample_data` column. If `sample_index` equals to 0 then the value in that row belongs to the sample from the first population. Otherwise it belongs to the sample from the second population.
The null hypothesis is that means of populations are equal. Normal distribution with equal variances is assumed.
**Arguments**
- `sample_data` — sample data. [Integer](../../../sql-reference/data-types/int-uint.md), [Float](../../../sql-reference/data-types/float.md) or [Decimal](../../../sql-reference/data-types/decimal.md).
- `sample_index` — sample index. [Integer](../../../sql-reference/data-types/int-uint.md).
**Returned values**
[Tuple](../../../sql-reference/data-types/tuple.md) with two elements:
- calculated t-statistic. [Float64](../../../sql-reference/data-types/float.md).
- calculated p-value. [Float64](../../../sql-reference/data-types/float.md).
**Example**
Input table:
``` text
┌─sample_data─┬─sample_index─┐
│ 20.3 │ 0 │
│ 21.1 │ 0 │
│ 21.9 │ 1 │
│ 21.7 │ 0 │
│ 19.9 │ 1 │
│ 21.8 │ 1 │
└─────────────┴──────────────┘
```
Query:
``` sql
SELECT studentTTest(sample_data, sample_index) FROM student_ttest;
```
Result:
``` text
┌─studentTTest(sample_data, sample_index)───┐
│ (-0.21739130434783777,0.8385421208415731) │
└───────────────────────────────────────────┘
```
**See Also**
- [Student's t-test](https://en.wikipedia.org/wiki/Student%27s_t-test)
- [welchTTest function](welchttest.md#welchttest)
[Original article](https://clickhouse.tech/docs/en/sql-reference/aggregate-functions/reference/studentttest/) <!--hide-->

2
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@ -16,7 +16,7 @@ This function doesn’t provide a guaranteed result. In certain situations, erro
We recommend using the `N < 10` value; performance is reduced with large `N` values. Maximum value of `N = 65536`.
**Parameters**
**Arguments**
- ‘N’ is the number of elements to return.

2
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@ -12,7 +12,7 @@ Similar to `topK` but takes one additional argument of integer type - `weight`.
topKWeighted(N)(x, weight)
```
**Parameters**
**Arguments**
- `N` — The number of elements to return.

2
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@ -10,7 +10,7 @@ Calculates the approximate number of different values of the argument.
uniq(x[, ...])
```
**Parameters**
**Arguments**
The function takes a variable number of parameters. Parameters can be `Tuple`, `Array`, `Date`, `DateTime`, `String`, or numeric types.

2
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@ -12,7 +12,7 @@ uniqCombined(HLL_precision)(x[, ...])
The `uniqCombined` function is a good choice for calculating the number of different values.
**Parameters**
**Arguments**
The function takes a variable number of parameters. Parameters can be `Tuple`, `Array`, `Date`, `DateTime`, `String`, or numeric types.

2
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@ -14,7 +14,7 @@ Use the `uniqExact` function if you absolutely need an exact result. Otherwise u
The `uniqExact` function uses more memory than `uniq`, because the size of the state has unbounded growth as the number of different values increases.
**Parameters**
**Arguments**
The function takes a variable number of parameters. Parameters can be `Tuple`, `Array`, `Date`, `DateTime`, `String`, or numeric types.

2
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@ -10,7 +10,7 @@ Calculates the approximate number of different argument values, using the [Hyper
uniqHLL12(x[, ...])
```
**Parameters**
**Arguments**
The function takes a variable number of parameters. Parameters can be `Tuple`, `Array`, `Date`, `DateTime`, `String`, or numeric types.

66
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@ -0,0 +1,66 @@
---
toc_priority: 301
toc_title: welchTTest
---
# welchTTest {#welchttest}
Applies Welch's t-test to samples from two populations.
**Syntax**
``` sql
welchTTest(sample_data, sample_index)
```
Values of both samples are in the `sample_data` column. If `sample_index` equals to 0 then the value in that row belongs to the sample from the first population. Otherwise it belongs to the sample from the second population.
The null hypothesis is that means of populations are equal. Normal distribution is assumed. Populations may have unequal variance.
**Arguments**
- `sample_data` — sample data. [Integer](../../../sql-reference/data-types/int-uint.md), [Float](../../../sql-reference/data-types/float.md) or [Decimal](../../../sql-reference/data-types/decimal.md).
- `sample_index` — sample index. [Integer](../../../sql-reference/data-types/int-uint.md).
**Returned values**
[Tuple](../../../sql-reference/data-types/tuple.md) with two elements:
- calculated t-statistic. [Float64](../../../sql-reference/data-types/float.md).
- calculated p-value. [Float64](../../../sql-reference/data-types/float.md).
**Example**
Input table:
``` text
┌─sample_data─┬─sample_index─┐
│ 20.3 │ 0 │
│ 22.1 │ 0 │
│ 21.9 │ 0 │
│ 18.9 │ 1 │
│ 20.3 │ 1 │
│ 19 │ 1 │
└─────────────┴──────────────┘
```
Query:
``` sql
SELECT welchTTest(sample_data, sample_index) FROM welch_ttest;
```
Result:
``` text
┌─welchTTest(sample_data, sample_index)─────┐
│ (2.7988719532211235,0.051807360348581945) │
└───────────────────────────────────────────┘
```
**See Also**
- [Welch's t-test](https://en.wikipedia.org/wiki/Welch%27s_t-test)
- [studentTTest function](studentttest.md#studentttest)
[Original article](https://clickhouse.tech/docs/en/sql-reference/aggregate-functions/reference/welchTTest/) <!--hide-->

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@ -0,0 +1,83 @@
---
toc_priority: 65
toc_title: Map(key, value)
---
# Map(key, value) {#data_type-map}
`Map(key, value)` data type stores `key:value` pairs.
**Parameters**
- `key` — The key part of the pair. [String](../../sql-reference/data-types/string.md) or [Integer](../../sql-reference/data-types/int-uint.md).
- `value` — The value part of the pair. [String](../../sql-reference/data-types/string.md), [Integer](../../sql-reference/data-types/int-uint.md) or [Array](../../sql-reference/data-types/array.md).
!!! warning "Warning"
Currently `Map` data type is an experimental feature. To work with it you must set `allow_experimental_map_type = 1`.
To get the value from an `a Map('key', 'value')` column, use `a['key']` syntax. This lookup works now with a linear complexity.
**Examples**
Consider the table:
``` sql
CREATE TABLE table_map (a Map(String, UInt64)) ENGINE=Memory;
INSERT INTO table_map VALUES ({'key1':1, 'key2':10}), ({'key1':2,'key2':20}), ({'key1':3,'key2':30});
```
Select all `key2` values:
```sql
SELECT a['key2'] FROM table_map;
```
Result:
```text
┌─arrayElement(a, 'key2')─┐
│ 10 │
│ 20 │
│ 30 │
└─────────────────────────┘
```
If there's no such `key` in the `Map()` column, the query returns zeros for numerical values, empty strings or empty arrays.
```sql
INSERT INTO table_map VALUES ({'key3':100}), ({});
SELECT a['key3'] FROM table_map;
```
Result:
```text
┌─arrayElement(a, 'key3')─┐
│ 100 │
│ 0 │
└─────────────────────────┘
┌─arrayElement(a, 'key3')─┐
│ 0 │
│ 0 │
│ 0 │
└─────────────────────────┘
```
## Convert Tuple to Map Type {#map-and-tuple}
You can cast `Tuple()` as `Map()` using [CAST](../../sql-reference/functions/type-conversion-functions.md#type_conversion_function-cast) function:
``` sql
SELECT CAST(([1, 2, 3], ['Ready', 'Steady', 'Go']), 'Map(UInt8, String)') AS map;
```
``` text
┌─map───────────────────────────┐
│ {1:'Ready',2:'Steady',3:'Go'} │
└───────────────────────────────┘
```
**See Also**
- [map()](../../sql-reference/functions/tuple-map-functions.md#function-map) function
- [CAST()](../../sql-reference/functions/type-conversion-functions.md#type_conversion_function-cast) function
[Original article](https://clickhouse.tech/docs/en/data-types/map/) <!--hide-->

4
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@ -208,8 +208,8 @@ This function returns the value for the specified `id`s and the date range that
Details of the algorithm:
- If the `id` is not found or a range is not found for the `id`, it returns the default value for the dictionary.
- If there are overlapping ranges, you can use any.
- If the range delimiter is `NULL` or an invalid date (such as 1900-01-01 or 2039-01-01), the range is left open. The range can be open on both sides.
- If there are overlapping ranges, it returns value for any (random) range.
- If the range delimiter is `NULL` or an invalid date (such as 1900-01-01), the range is open. The range can be open on both sides.
Configuration example:

44
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@ -61,7 +61,7 @@ Combines arrays passed as arguments.
arrayConcat(arrays)
```
**Parameters**
**Arguments**
- `arrays` – Arbitrary number of arguments of [Array](../../sql-reference/data-types/array.md) type.
**Example**
@ -111,7 +111,7 @@ Checks whether one array is a subset of another.
hasAll(set, subset)
```
**Parameters**
**Arguments**
- `set` – Array of any type with a set of elements.
- `subset` – Array of any type with elements that should be tested to be a subset of `set`.
@ -149,7 +149,7 @@ Checks whether two arrays have intersection by some elements.
hasAny(array1, array2)
```
**Parameters**
**Arguments**
- `array1` – Array of any type with a set of elements.
- `array2` – Array of any type with a set of elements.
@ -191,7 +191,7 @@ For Example:
- `hasSubstr([1,2,3,4], [2,3])` returns 1. However, `hasSubstr([1,2,3,4], [3,2])` will return `0`.
- `hasSubstr([1,2,3,4], [1,2,3])` returns 1. However, `hasSubstr([1,2,3,4], [1,2,4])` will return `0`.
**Parameters**
**Arguments**
- `array1` – Array of any type with a set of elements.
- `array2` – Array of any type with a set of elements.
@ -369,7 +369,7 @@ Removes the last item from the array.
arrayPopBack(array)
```
**Parameters**
**Arguments**
- `array` – Array.
@ -393,7 +393,7 @@ Removes the first item from the array.
arrayPopFront(array)
```
**Parameters**
**Arguments**
- `array` – Array.
@ -417,7 +417,7 @@ Adds one item to the end of the array.
arrayPushBack(array, single_value)
```
**Parameters**
**Arguments**
- `array` – Array.
- `single_value` – A single value. Only numbers can be added to an array with numbers, and only strings can be added to an array of strings. When adding numbers, ClickHouse automatically sets the `single_value` type for the data type of the array. For more information about the types of data in ClickHouse, see “[Data types](../../sql-reference/data-types/index.md#data_types)”. Can be `NULL`. The function adds a `NULL` element to an array, and the type of array elements converts to `Nullable`.
@ -442,7 +442,7 @@ Adds one element to the beginning of the array.
arrayPushFront(array, single_value)
```
**Parameters**
**Arguments**
- `array` – Array.
- `single_value` – A single value. Only numbers can be added to an array with numbers, and only strings can be added to an array of strings. When adding numbers, ClickHouse automatically sets the `single_value` type for the data type of the array. For more information about the types of data in ClickHouse, see “[Data types](../../sql-reference/data-types/index.md#data_types)”. Can be `NULL`. The function adds a `NULL` element to an array, and the type of array elements converts to `Nullable`.
@ -467,7 +467,7 @@ Changes the length of the array.
arrayResize(array, size[, extender])
```
**Parameters:**
**Arguments:**
- `array` — Array.
- `size` — Required length of the array.
@ -509,7 +509,7 @@ Returns a slice of the array.
arraySlice(array, offset[, length])
```
**Parameters**
**Arguments**
- `array` – Array of data.
- `offset` – Indent from the edge of the array. A positive value indicates an offset on the left, and a negative value is an indent on the right. Numbering of the array items begins with 1.
@ -751,7 +751,7 @@ Calculates the difference between adjacent array elements. Returns an array wher
arrayDifference(array)
```
**Parameters**
**Arguments**
- `array` – [Array](https://clickhouse.tech/docs/en/data_types/array/).
@ -803,7 +803,7 @@ Takes an array, returns an array containing the distinct elements only.
arrayDistinct(array)
```
**Parameters**
**Arguments**
- `array` – [Array](https://clickhouse.tech/docs/en/data_types/array/).
@ -871,7 +871,7 @@ Applies an aggregate function to array elements and returns its result. The name
arrayReduce(agg_func, arr1, arr2, ..., arrN)
```
**Parameters**
**Arguments**
- `agg_func` — The name of an aggregate function which should be a constant [string](../../sql-reference/data-types/string.md).
- `arr` — Any number of [array](../../sql-reference/data-types/array.md) type columns as the parameters of the aggregation function.
@ -936,7 +936,7 @@ Applies an aggregate function to array elements in given ranges and returns an a
arrayReduceInRanges(agg_func, ranges, arr1, arr2, ..., arrN)
```
**Parameters**
**Arguments**
- `agg_func` — The name of an aggregate function which should be a constant [string](../../sql-reference/data-types/string.md).
- `ranges` — The ranges to aggretate which should be an [array](../../sql-reference/data-types/array.md) of [tuples](../../sql-reference/data-types/tuple.md) which containing the index and the length of each range.
@ -1007,7 +1007,7 @@ flatten(array_of_arrays)
Alias: `flatten`.
**Parameters**
**Arguments**
- `array_of_arrays` — [Array](../../sql-reference/data-types/array.md) of arrays. For example, `[[1,2,3], [4,5]]`.
@ -1033,7 +1033,7 @@ Removes consecutive duplicate elements from an array. The order of result values
arrayCompact(arr)
```
**Parameters**
**Arguments**
`arr` — The [array](../../sql-reference/data-types/array.md) to inspect.
@ -1069,7 +1069,7 @@ Combines multiple arrays into a single array. The resulting array contains the c
arrayZip(arr1, arr2, ..., arrN)
```
**Parameters**
**Arguments**
- `arrN` — [Array](../../sql-reference/data-types/array.md).
@ -1107,7 +1107,7 @@ Calculate AUC (Area Under the Curve, which is a concept in machine learning, see
arrayAUC(arr_scores, arr_labels)
```
**Parameters**
**Arguments**
- `arr_scores` — scores prediction model gives.
- `arr_labels` — labels of samples, usually 1 for positive sample and 0 for negtive sample.
@ -1302,7 +1302,7 @@ Note that the `arrayMin` is a [higher-order function](../../sql-reference/functi
arrayMin([func,] arr)
```
**Parameters**
**Arguments**
- `func` — Function. [Expression](../../sql-reference/data-types/special-data-types/expression.md).
- `arr` — Array. [Array](../../sql-reference/data-types/array.md).
@ -1357,7 +1357,7 @@ Note that the `arrayMax` is a [higher-order function](../../sql-reference/functi
arrayMax([func,] arr)
```
**Parameters**
**Arguments**
- `func` — Function. [Expression](../../sql-reference/data-types/special-data-types/expression.md).
- `arr` — Array. [Array](../../sql-reference/data-types/array.md).
@ -1412,7 +1412,7 @@ Note that the `arraySum` is a [higher-order function](../../sql-reference/functi
arraySum([func,] arr)
```
**Parameters**
**Arguments**
- `func` — Function. [Expression](../../sql-reference/data-types/special-data-types/expression.md).
- `arr` — Array. [Array](../../sql-reference/data-types/array.md).
@ -1467,7 +1467,7 @@ Note that the `arrayAvg` is a [higher-order function](../../sql-reference/functi
arrayAvg([func,] arr)
```
**Parameters**
**Arguments**
- `func` — Function. [Expression](../../sql-reference/data-types/special-data-types/expression.md).
- `arr` — Array. [Array](../../sql-reference/data-types/array.md).

8
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@ -35,7 +35,7 @@ Takes any integer and converts it into [binary form](https://en.wikipedia.org/wi
SELECT bitTest(number, index)
```
**Parameters**
**Arguments**
- `number` – integer number.
- `index` – position of bit.
@ -100,7 +100,7 @@ The conjuction for bitwise operations:
SELECT bitTestAll(number, index1, index2, index3, index4, ...)
```
**Parameters**
**Arguments**
- `number` – integer number.
- `index1`, `index2`, `index3`, `index4` – positions of bit. For example, for set of positions (`index1`, `index2`, `index3`, `index4`) is true if and only if all of its positions are true (`index1` ⋀ `index2`, ⋀ `index3` ⋀ `index4`).
@ -165,7 +165,7 @@ The disjunction for bitwise operations:
SELECT bitTestAny(number, index1, index2, index3, index4, ...)
```
**Parameters**
**Arguments**
- `number` – integer number.
- `index1`, `index2`, `index3`, `index4` – positions of bit.
@ -220,7 +220,7 @@ Calculates the number of bits set to one in the binary representation of a numbe
bitCount(x)
```
**Parameters**
**Arguments**
- `x` — [Integer](../../sql-reference/data-types/int-uint.md) or [floating-point](../../sql-reference/data-types/float.md) number. The function uses the value representation in memory. It allows supporting floating-point numbers.

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@ -21,7 +21,7 @@ Build a bitmap from unsigned integer array.
bitmapBuild(array)
```
**Parameters**
**Arguments**
- `array` – unsigned integer array.
@ -45,7 +45,7 @@ Convert bitmap to integer array.
bitmapToArray(bitmap)
```
**Parameters**
**Arguments**
- `bitmap` – bitmap object.
@ -69,7 +69,7 @@ Return subset in specified range (not include the range_end).
bitmapSubsetInRange(bitmap, range_start, range_end)
```
**Parameters**
**Arguments**
- `bitmap` – [Bitmap object](#bitmap_functions-bitmapbuild).
- `range_start` – range start point. Type: [UInt32](../../sql-reference/data-types/int-uint.md).
@ -97,7 +97,7 @@ Creates a subset of bitmap with n elements taken between `range_start` and `card
bitmapSubsetLimit(bitmap, range_start, cardinality_limit)
```
**Parameters**
**Arguments**
- `bitmap` – [Bitmap object](#bitmap_functions-bitmapbuild).
- `range_start` – The subset starting point. Type: [UInt32](../../sql-reference/data-types/int-uint.md).
@ -133,7 +133,7 @@ Checks whether the bitmap contains an element.
bitmapContains(haystack, needle)
```
**Parameters**
**Arguments**
- `haystack` – [Bitmap object](#bitmap_functions-bitmapbuild), where the function searches.
- `needle` – Value that the function searches. Type: [UInt32](../../sql-reference/data-types/int-uint.md).
@ -167,7 +167,7 @@ bitmapHasAny(bitmap1, bitmap2)
If you are sure that `bitmap2` contains strictly one element, consider using the [bitmapContains](#bitmap_functions-bitmapcontains) function. It works more efficiently.
**Parameters**
**Arguments**
- `bitmap*` – bitmap object.
@ -197,7 +197,7 @@ If the second argument is an empty bitmap then returns 1.
bitmapHasAll(bitmap,bitmap)
```
**Parameters**
**Arguments**
- `bitmap` – bitmap object.
@ -221,7 +221,7 @@ Retrun bitmap cardinality of type UInt64.
bitmapCardinality(bitmap)
```
**Parameters**
**Arguments**
- `bitmap` – bitmap object.
@ -243,7 +243,7 @@ Retrun the smallest value of type UInt64 in the set, UINT32_MAX if the set is em
bitmapMin(bitmap)
**Parameters**
**Arguments**
- `bitmap` – bitmap object.
@ -263,7 +263,7 @@ Retrun the greatest value of type UInt64 in the set, 0 if the set is empty.
bitmapMax(bitmap)
**Parameters**
**Arguments**
- `bitmap` – bitmap object.
@ -283,7 +283,7 @@ Transform an array of values in a bitmap to another array of values, the result
bitmapTransform(bitmap, from_array, to_array)
**Parameters**
**Arguments**
- `bitmap` – bitmap object.
- `from_array` – UInt32 array. For idx in range \[0, from_array.size()), if bitmap contains from_array\[idx\], then replace it with to_array\[idx\]. Note that the result depends on array ordering if there are common elements between from_array and to_array.
@ -307,7 +307,7 @@ Two bitmap and calculation, the result is a new bitmap.
bitmapAnd(bitmap,bitmap)
```
**Parameters**
**Arguments**
- `bitmap` – bitmap object.
@ -331,7 +331,7 @@ Two bitmap or calculation, the result is a new bitmap.
bitmapOr(bitmap,bitmap)
```
**Parameters**
**Arguments**
- `bitmap` – bitmap object.
@ -355,7 +355,7 @@ Two bitmap xor calculation, the result is a new bitmap.
bitmapXor(bitmap,bitmap)
```
**Parameters**
**Arguments**
- `bitmap` – bitmap object.
@ -379,7 +379,7 @@ Two bitmap andnot calculation, the result is a new bitmap.
bitmapAndnot(bitmap,bitmap)
```
**Parameters**
**Arguments**
- `bitmap` – bitmap object.
@ -403,7 +403,7 @@ Two bitmap and calculation, return cardinality of type UInt64.
bitmapAndCardinality(bitmap,bitmap)
```
**Parameters**
**Arguments**
- `bitmap` – bitmap object.
@ -427,7 +427,7 @@ Two bitmap or calculation, return cardinality of type UInt64.
bitmapOrCardinality(bitmap,bitmap)
```
**Parameters**
**Arguments**
- `bitmap` – bitmap object.
@ -451,7 +451,7 @@ Two bitmap xor calculation, return cardinality of type UInt64.
bitmapXorCardinality(bitmap,bitmap)
```
**Parameters**
**Arguments**
- `bitmap` – bitmap object.
@ -475,7 +475,7 @@ Two bitmap andnot calculation, return cardinality of type UInt64.
bitmapAndnotCardinality(bitmap,bitmap)
```
**Parameters**
**Arguments**
- `bitmap` – bitmap object.

4
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@ -17,7 +17,7 @@ SELECT if(cond, then, else)
If the condition `cond` evaluates to a non-zero value, returns the result of the expression `then`, and the result of the expression `else`, if present, is skipped. If the `cond` is zero or `NULL`, then the result of the `then` expression is skipped and the result of the `else` expression, if present, is returned.
**Parameters**
**Arguments**
- `cond` – The condition for evaluation that can be zero or not. The type is UInt8, Nullable(UInt8) or NULL.
- `then` - The expression to return if condition is met.
@ -117,7 +117,7 @@ Allows you to write the [CASE](../../sql-reference/operators/index.md#operator_c
Syntax: `multiIf(cond_1, then_1, cond_2, then_2, ..., else)`
**Parameters:**
**Arguments:**
- `cond_N` — The condition for the function to return `then_N`.
- `then_N` — The result of the function when executed.

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