Merge branch 'master' of https://github.com/ClickHouse/ClickHouse into hdfs-idisk

2024-11-25 09:02:00 +00:00 · 2021-04-22 07:41:55 +00:00 · 2021-04-22 07:41:55 +00:00 · 7d1e5e6a08
commit 7d1e5e6a08
parent 87b4843134 f125db243e
126 changed files with 5277 additions and 437 deletions
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@ -516,9 +516,9 @@ include (cmake/find/fast_float.cmake)
 include (cmake/find/rapidjson.cmake)
 include (cmake/find/fastops.cmake)
 include (cmake/find/odbc.cmake)
+include (cmake/find/nanodbc.cmake)
 include (cmake/find/rocksdb.cmake)
 include (cmake/find/libpqxx.cmake)
-include (cmake/find/nanodbc.cmake)
 include (cmake/find/nuraft.cmake)


--- a/cmake/find/nanodbc.cmake
+++ b/cmake/find/nanodbc.cmake
@ -1,35 +1,16 @@
-option(ENABLE_NANODBC "Enalbe nanodbc" ${ENABLE_LIBRARIES})
-
-if (NOT ENABLE_NANODBC)
-    set (USE_ODBC 0)
-    return()
-endif()
-
 if (NOT ENABLE_ODBC)
-    set (USE_NANODBC 0)
-    message (STATUS "Using nanodbc=${USE_NANODBC}")
-    return()
-endif()
+    return ()
+endif ()
+
+if (NOT USE_INTERNAL_NANODBC_LIBRARY)
+    message (FATAL_ERROR "Only the bundled nanodbc library can be used")
+endif ()

 if (NOT EXISTS "${ClickHouse_SOURCE_DIR}/contrib/nanodbc/CMakeLists.txt")
-    message (WARNING "submodule contrib/nanodbc is missing. to fix try run: \n git submodule update --init --recursive")
-    message (${RECONFIGURE_MESSAGE_LEVEL} "Can't find internal nanodbc library")
-    set (USE_NANODBC 0)
-    return()
+    message (FATAL_ERROR "submodule contrib/nanodbc is missing. to fix try run: \n git submodule update --init --recursive")
 endif()

-if (NOT EXISTS "${ClickHouse_SOURCE_DIR}/contrib/unixodbc/include")
-    message (ERROR "submodule contrib/unixodbc is missing. to fix try run: \n git submodule update --init --recursive")
-    message (${RECONFIGURE_MESSAGE_LEVEL} "Can't find internal unixodbc needed for nanodbc")
-    set (USE_NANODBC 0)
-    return()
-endif()
-
-set (USE_NANODBC 1)
-
 set (NANODBC_LIBRARY nanodbc)
+set (NANODBC_INCLUDE_DIR "${ClickHouse_SOURCE_DIR}/contrib/nanodbc/nanodbc")

-set (NANODBC_INCLUDE_DIR "${ClickHouse_SOURCE_DIR}/contrib/nanodbc/nanodbce")
-
-message (STATUS "Using nanodbc=${USE_NANODBC}: ${NANODBC_INCLUDE_DIR} : ${NANODBC_LIBRARY}")
-message (STATUS "Using unixodbc")
+message (STATUS "Using nanodbc: ${NANODBC_INCLUDE_DIR} : ${NANODBC_LIBRARY}")
--- a/cmake/find/odbc.cmake
+++ b/cmake/find/odbc.cmake
@ -50,4 +50,6 @@ if (NOT EXTERNAL_ODBC_LIBRARY_FOUND)
    set (USE_INTERNAL_ODBC_LIBRARY 1)
 endif ()

+set (USE_INTERNAL_NANODBC_LIBRARY 1)
+
 message (STATUS "Using unixodbc")
--- a/contrib/CMakeLists.txt
+++ b/contrib/CMakeLists.txt
@ -47,6 +47,7 @@ add_subdirectory (lz4-cmake)
 add_subdirectory (murmurhash)
 add_subdirectory (replxx-cmake)
 add_subdirectory (unixodbc-cmake)
+add_subdirectory (nanodbc-cmake)

 if (USE_INTERNAL_XZ_LIBRARY)
    add_subdirectory (xz)
@ -320,10 +321,6 @@ if (USE_LIBPQXX)
    add_subdirectory (libpqxx-cmake)
 endif()

-if (USE_NANODBC)
-    add_subdirectory (nanodbc-cmake)
-endif()
-
 if (USE_NURAFT)
  add_subdirectory(nuraft-cmake)
 endif()
--- a/contrib/nanodbc-cmake/CMakeLists.txt
+++ b/contrib/nanodbc-cmake/CMakeLists.txt
@ -1,3 +1,7 @@
+if (NOT USE_INTERNAL_NANODBC_LIBRARY)
+    return ()
+endif ()
+
 set (LIBRARY_DIR ${ClickHouse_SOURCE_DIR}/contrib/nanodbc)

 if (NOT TARGET unixodbc)
--- a/contrib/zlib-ng
+++ b/contrib/zlib-ng
@ -1 +1 @@
-Subproject commit 7f254522fd676ff4e906c6d4e9b30d4df4214c2d
+Subproject commit 5cc4d232020dc66d1d6c5438834457e2a2f6127b
--- a/docker/packager/binary/Dockerfile
+++ b/docker/packager/binary/Dockerfile
@ -42,15 +42,12 @@ RUN apt-get update \
        clang-tidy-10 \
        clang-tidy-11 \
        cmake \
-        cmake \
        curl \
        g++-9 \
        gcc-9 \
        gdb \
        git \
        gperf \
-        gperf \
-        intel-opencl-icd \
        libicu-dev \
        libreadline-dev \
        lld-10 \
@ -61,10 +58,7 @@ RUN apt-get update \
        llvm-11-dev \
        moreutils \
        ninja-build \
-        ocl-icd-libopencl1 \
-        opencl-headers \
        pigz \
-        pixz \
        rename \
        tzdata \
        --yes --no-install-recommends
--- a/docker/packager/unbundled/Dockerfile
+++ b/docker/packager/unbundled/Dockerfile
@ -35,9 +35,6 @@ RUN apt-get update \
        libjemalloc-dev \
        libmsgpack-dev \
        libcurl4-openssl-dev \
-        opencl-headers \
-        ocl-icd-libopencl1 \
-        intel-opencl-icd \
        unixodbc-dev \
        odbcinst \
        tzdata \
--- a/docker/test/fasttest/run.sh
+++ b/docker/test/fasttest/run.sh
@ -308,10 +308,8 @@ function run_tests
        01354_order_by_tuple_collate_const
        01355_ilike
        01411_bayesian_ab_testing
-        01532_collate_in_low_cardinality
-        01533_collate_in_nullable
-        01542_collate_in_array
-        01543_collate_in_tuple
+        collate
+        collation
        _orc_
        arrow
        avro
--- a/docker/test/stateless_unbundled/Dockerfile
+++ b/docker/test/stateless_unbundled/Dockerfile
@ -14,9 +14,7 @@ RUN apt-get --allow-unauthenticated update -y \
            expect \
            gdb  \
            gperf \
-            gperf \
            heimdal-multidev \
-            intel-opencl-icd \
            libboost-filesystem-dev \
            libboost-iostreams-dev \
            libboost-program-options-dev \
@ -50,9 +48,7 @@ RUN apt-get --allow-unauthenticated update -y \
            moreutils \
            ncdu \
            netcat-openbsd \
-            ocl-icd-libopencl1 \
            odbcinst \
-            opencl-headers \
            openssl \
            perl \
            pigz \
--- a/docs/en/development/build.md
+++ b/docs/en/development/build.md
@ -27,53 +27,20 @@ Or cmake3 instead of cmake on older systems.

 On Ubuntu/Debian you can use the automatic installation script (check [official webpage](https://apt.llvm.org/))

-```bash 
+```bash
 sudo bash -c "$(wget -O - https://apt.llvm.org/llvm.sh)"
 ```

 For other Linux distribution - check the availability of the [prebuild packages](https://releases.llvm.org/download.html) or build clang [from sources](https://clang.llvm.org/get_started.html).

-#### Use clang-11 for Builds {#use-gcc-10-for-builds}
+#### Use clang-11 for Builds

 ``` bash
 $ export CC=clang-11
 $ export CXX=clang++-11
 ```

-### Install GCC 10 {#install-gcc-10}
-
-We recommend building ClickHouse with clang-11, GCC-10 also supported, but it is not used for production builds.
-
-If you want to use GCC-10 there are several ways to install it.
-
-#### Install from Repository {#install-from-repository}
-
-On Ubuntu 19.10 or newer:
-
-    $ sudo apt-get update
-    $ sudo apt-get install gcc-10 g++-10
-
-#### Install from a PPA Package {#install-from-a-ppa-package}
-
-On older Ubuntu:
-
-``` bash
-$ sudo apt-get install software-properties-common
-$ sudo apt-add-repository ppa:ubuntu-toolchain-r/test
-$ sudo apt-get update
-$ sudo apt-get install gcc-10 g++-10
-```
-
-#### Install from Sources {#install-from-sources}
-
-See [utils/ci/build-gcc-from-sources.sh](https://github.com/ClickHouse/ClickHouse/blob/master/utils/ci/build-gcc-from-sources.sh)
-
-#### Use GCC 10 for Builds {#use-gcc-10-for-builds}
-
-``` bash
-$ export CC=gcc-10
-$ export CXX=g++-10
-```
+Gcc can also be used though it is discouraged.

 ### Checkout ClickHouse Sources {#checkout-clickhouse-sources}

--- a/docs/en/development/developer-instruction.md
+++ b/docs/en/development/developer-instruction.md
@ -131,17 +131,18 @@ ClickHouse uses several external libraries for building. All of them do not need

 ## C++ Compiler {#c-compiler}

-Compilers GCC starting from version 10 and Clang version 8 or above are supported for building ClickHouse.
+Compilers Clang starting from version 11 is supported for building ClickHouse.

-Official Yandex builds currently use GCC because it generates machine code of slightly better performance (yielding a difference of up to several percent according to our benchmarks). And Clang is more convenient for development usually. Though, our continuous integration (CI) platform runs checks for about a dozen of build combinations.
+Clang should be used instead of gcc. Though, our continuous integration (CI) platform runs checks for about a dozen of build combinations.

-To install GCC on Ubuntu run: `sudo apt install gcc g++`
+On Ubuntu/Debian you can use the automatic installation script (check [official webpage](https://apt.llvm.org/))

-Check the version of gcc: `gcc --version`. If it is below 10, then follow the instruction here: https://clickhouse.tech/docs/en/development/build/#install-gcc-10.
+```bash
+sudo bash -c "$(wget -O - https://apt.llvm.org/llvm.sh)"
+```

-Mac OS X build is supported only for Clang. Just run `brew install llvm`
+Mac OS X build is also supported. Just run `brew install llvm`

-If you decide to use Clang, you can also install `libc++` and `lld`, if you know what it is. Using `ccache` is also recommended.

 ## The Building Process {#the-building-process}

@ -152,14 +153,7 @@ Now that you are ready to build ClickHouse we recommend you to create a separate

 You can have several different directories (build_release, build_debug, etc.) for different types of build.

-While inside the `build` directory, configure your build by running CMake. Before the first run, you need to define environment variables that specify compiler (version 10 gcc compiler in this example).
-
-Linux:
-
-    export CC=gcc-10 CXX=g++-10
-    cmake ..
-
-Mac OS X:
+While inside the `build` directory, configure your build by running CMake. Before the first run, you need to define environment variables that specify compiler.

    export CC=clang CXX=clang++
    cmake ..
--- a/docs/en/development/style.md
+++ b/docs/en/development/style.md
@ -701,7 +701,7 @@ But other things being equal, cross-platform or portable code is preferred.

 **2.** Language: C++20 (see the list of available [C++20 features](https://en.cppreference.com/w/cpp/compiler_support#C.2B.2B20_features)).

-**3.** Compiler: `gcc`. At this time (August 2020), the code is compiled using version 9.3. (It can also be compiled using `clang 8`.)
+**3.** Compiler: `clang`. At this time (April 2021), the code is compiled using clang version 11. (It can also be compiled using `gcc` version 10, but it's untested and not suitable for production usage).

 The standard library is used (`libc++`).

@ -711,7 +711,7 @@ The standard library is used (`libc++`).

 The CPU instruction set is the minimum supported set among our servers. Currently, it is SSE 4.2.

-**6.** Use `-Wall -Wextra -Werror` compilation flags.
+**6.** Use `-Wall -Wextra -Werror` compilation flags. Also `-Weverything` is used with few exceptions.

 **7.** Use static linking with all libraries except those that are difficult to connect to statically (see the output of the `ldd` command).

--- a/docs/en/operations/performance-test.md
+++ b/docs/en/operations/performance-test.md
@ -12,6 +12,7 @@ With this instruction you can run basic ClickHouse performance test on any serve
 3.  Copy the link to `clickhouse` binary for amd64 or aarch64.
 4.  ssh to the server and download it with wget:
 ```bash
+# These links are outdated, please obtain the fresh link from the "commits" page.
 # For amd64:
 wget https://clickhouse-builds.s3.yandex.net/0/e29c4c3cc47ab2a6c4516486c1b77d57e7d42643/clickhouse_build_check/gcc-10_relwithdebuginfo_none_bundled_unsplitted_disable_False_binary/clickhouse
 # For aarch64:
--- a/docs/en/operations/settings/settings.md
+++ b/docs/en/operations/settings/settings.md
@ -854,8 +854,6 @@ For example, when reading from a table, if it is possible to evaluate expression

 Default value: the number of physical CPU cores.

-If less than one SELECT query is normally run on a server at a time, set this parameter to a value slightly less than the actual number of processor cores.
-
 For queries that are completed quickly because of a LIMIT, you can set a lower ‘max_threads’. For example, if the necessary number of entries are located in every block and max_threads = 8, then 8 blocks are retrieved, although it would have been enough to read just one.

 The smaller the `max_threads` value, the less memory is consumed.
--- a/docs/en/operations/system-tables/replication_queue.md
+++ b/docs/en/operations/system-tables/replication_queue.md
@ -15,16 +15,16 @@ Columns:
 -   `node_name` ([String](../../sql-reference/data-types/string.md)) — Node name in ZooKeeper.

 -   `type` ([String](../../sql-reference/data-types/string.md)) — Type of the task in the queue, one of:
-    - `GET_PART`       - Get the part from another replica.
-    - `ATTACH_PART`    - Attach the part, possibly from our own replica (if found in `detached` folder). 
-    You may think of it as a `GET_PART` with some optimisations as they're nearly identical.
-    - `MERGE_PARTS`    - Merge the parts.
-    - `DROP_RANGE`     - Delete the parts in the specified partition in the specified number range.
-    - `CLEAR_COLUMN`   - NOTE: Deprecated. Drop specific column from specified partition.
-    - `CLEAR_INDEX`    - NOTE: Deprecated. Drop specific index from specified partition.
-    - `REPLACE_RANGE`  - Drop certain range of partitions and replace them by new ones
-    - `MUTATE_PART`    - Apply one or several mutations to the part.
-    - `ALTER_METADATA` - Apply alter modification according to global /metadata and /columns paths
+
+    -   `GET_PART` — Get the part from another replica.
+    -   `ATTACH_PART` — Attach the part, possibly from our own replica (if found in the `detached` folder). You may think of it as a `GET_PART` with some optimizations as they're nearly identical.
+    -   `MERGE_PARTS` — Merge the parts.
+    -   `DROP_RANGE` — Delete the parts in the specified partition in the specified number range.
+    -   `CLEAR_COLUMN` — NOTE: Deprecated. Drop specific column from specified partition.
+    -   `CLEAR_INDEX` — NOTE: Deprecated. Drop specific index from specified partition.
+    -   `REPLACE_RANGE` — Drop a certain range of parts and replace them with new ones.
+    -   `MUTATE_PART` — Apply one or several mutations to the part.
+    -   `ALTER_METADATA` — Apply alter modification according to global /metadata and /columns paths.

 -   `create_time` ([Datetime](../../sql-reference/data-types/datetime.md)) — Date and time when the task was submitted for execution.

--- a/docs/en/sql-reference/aggregate-functions/combinators.md
+++ b/docs/en/sql-reference/aggregate-functions/combinators.md
@ -27,7 +27,37 @@ Example 2: `uniqArray(arr)` – Counts the number of unique elements in all ‘a

 ## -SimpleState {#agg-functions-combinator-simplestate}

-If you apply this combinator, the aggregate function returns the same value but with a different type. This is an `SimpleAggregateFunction(...)` that can be stored in a table to work with [AggregatingMergeTree](../../engines/table-engines/mergetree-family/aggregatingmergetree.md) table engines.
+If you apply this combinator, the aggregate function returns the same value but with a different type. This is a [SimpleAggregateFunction(...)](../../sql-reference/data-types/simpleaggregatefunction.md) that can be stored in a table to work with [AggregatingMergeTree](../../engines/table-engines/mergetree-family/aggregatingmergetree.md) tables.
+
+**Syntax**
+
+``` sql
+<aggFunction>SimpleState(x)
+```
+
+**Arguments**
+
+-   `x` — Aggregate function parameters.
+
+**Returned values**
+
+The value of an aggregate function with the `SimpleAggregateFunction(...)` type.
+
+**Example**
+
+Query:
+
+``` sql
+WITH anySimpleState(number) AS c SELECT toTypeName(c), c FROM numbers(1);
+```
+
+Result:
+
+``` text
+┌─toTypeName(c)────────────────────────┬─c─┐
+│ SimpleAggregateFunction(any, UInt64) │ 0 │
+└──────────────────────────────────────┴───┘
+```

 ## -State {#agg-functions-combinator-state}

@ -249,4 +279,3 @@ FROM people
 └────────┴───────────────────────────┘
 ```

-
--- a/docs/en/sql-reference/data-types/simpleaggregatefunction.md
+++ b/docs/en/sql-reference/data-types/simpleaggregatefunction.md
@ -2,6 +2,8 @@

 `SimpleAggregateFunction(name, types_of_arguments…)` data type stores current value of the aggregate function, and does not store its full state as [`AggregateFunction`](../../sql-reference/data-types/aggregatefunction.md) does. This optimization can be applied to functions for which the following property holds: the result of applying a function `f` to a row set `S1 UNION ALL S2` can be obtained by applying `f` to parts of the row set separately, and then again applying `f` to the results: `f(S1 UNION ALL S2) = f(f(S1) UNION ALL f(S2))`. This property guarantees that partial aggregation results are enough to compute the combined one, so we don’t have to store and process any extra data.

+The common way to produce an aggregate function value is by calling the aggregate function with the [-SimpleState](../../sql-reference/aggregate-functions/combinators.md#agg-functions-combinator-simplestate) suffix.
+
 The following aggregate functions are supported:

 -   [`any`](../../sql-reference/aggregate-functions/reference/any.md#agg_function-any)
--- a/docs/en/sql-reference/functions/other-functions.md
+++ b/docs/en/sql-reference/functions/other-functions.md
@ -1192,6 +1192,109 @@ SELECT defaultValueOfTypeName('Nullable(Int8)')
 └──────────────────────────────────────────┘
 ```

+## indexHint {#indexhint}
+The function is intended for debugging and introspection purposes. The function ignores it's argument and always returns 1. Arguments are not even evaluated.
+
+But for the purpose of index analysis, the argument of this function is analyzed as if it was present directly without being wrapped inside `indexHint` function. This allows to select data in index ranges by the corresponding condition but without further filtering by this condition. The index in ClickHouse is sparse and using `indexHint` will yield more data than specifying the same condition directly.
+
+**Syntax**
+
+```sql
+SELECT * FROM table WHERE indexHint(<expression>)
+```
+
+**Returned value**
+
+1. Type: [Uint8](https://clickhouse.yandex/docs/en/data_types/int_uint/#diapazony-uint).
+
+**Example**
+
+Here is the example of test data from the table [ontime](../../getting-started/example-datasets/ontime.md).
+
+Input table:
+
+```sql
+SELECT count() FROM ontime
+```
+
+```text
+┌─count()─┐
+│ 4276457 │
+└─────────┘
+```
+
+The table has indexes on the fields `(FlightDate, (Year, FlightDate))`.
+
+Create a query, where the index is not used.
+
+Query:
+
+```sql
+SELECT FlightDate AS k, count() FROM ontime GROUP BY k ORDER BY k
+```
+
+ClickHouse processed the entire table (`Processed 4.28 million rows`).
+
+Result:
+
+```text
+┌──────────k─┬─count()─┐
+│ 2017-01-01 │   13970 │
+│ 2017-01-02 │   15882 │
+........................
+│ 2017-09-28 │   16411 │
+│ 2017-09-29 │   16384 │
+│ 2017-09-30 │   12520 │
+└────────────┴─────────┘
+```
+
+To apply the index, select a specific date.
+
+Query:
+
+```sql
+SELECT FlightDate AS k, count() FROM ontime WHERE k = '2017-09-15' GROUP BY k ORDER BY k
+```
+
+By using the index, ClickHouse processed a significantly smaller number of rows (`Processed 32.74 thousand rows`).
+
+Result:
+
+```text
+┌──────────k─┬─count()─┐
+│ 2017-09-15 │   16428 │
+└────────────┴─────────┘
+```
+
+Now wrap the expression `k = '2017-09-15'` into `indexHint` function.
+
+Query:
+
+```sql
+SELECT
+    FlightDate AS k,
+    count()
+FROM ontime
+WHERE indexHint(k = '2017-09-15')
+GROUP BY k
+ORDER BY k ASC
+```
+
+ClickHouse used the index in the same way as the previous time (`Processed 32.74 thousand rows`).
+The expression `k = '2017-09-15'` was not used when generating the result.
+In examle the `indexHint` function allows to see adjacent dates.
+
+Result:
+
+```text
+┌──────────k─┬─count()─┐
+│ 2017-09-14 │    7071 │
+│ 2017-09-15 │   16428 │
+│ 2017-09-16 │    1077 │
+│ 2017-09-30 │    8167 │
+└────────────┴─────────┘
+```
+
 ## replicate {#other-functions-replicate}

 Creates an array with a single value.
--- a/docs/en/sql-reference/statements/alter/partition.md
+++ b/docs/en/sql-reference/statements/alter/partition.md
@ -88,12 +88,10 @@ Read more about setting the partition expression in a section [How to specify th
 This query is replicated. The replica-initiator checks whether there is data in the `detached` directory. 
 If data exists, the query checks its integrity. If everything is correct, the query adds the data to the table.

-If the non-initiator replica, receiving the attach command, finds the part with the correct checksums in its own 
-`detached` folder, it attaches the data without fetching it from other replicas.
+If the non-initiator replica, receiving the attach command, finds the part with the correct checksums in its own `detached` folder, it attaches the data without fetching it from other replicas.
 If there is no part with the correct checksums, the data is downloaded from any replica having the part.

-You can put data to the `detached` directory on one replica and use the `ALTER ... ATTACH` query to add it to the 
-table on all replicas.
+You can put data to the `detached` directory on one replica and use the `ALTER ... ATTACH` query to add it to the table on all replicas.

 ## ATTACH PARTITION FROM {#alter_attach-partition-from}

@ -101,8 +99,8 @@ table on all replicas.
 ALTER TABLE table2 ATTACH PARTITION partition_expr FROM table1
 ```

-This query copies the data partition from the `table1` to `table2`.
-Note that data won't be deleted neither from `table1` nor from `table2`.
+This query copies the data partition from `table1` to `table2`.
+Note that data will be deleted neither from `table1` nor from `table2`.

 For the query to run successfully, the following conditions must be met:

--- a/docs/en/sql-reference/statements/system.md
+++ b/docs/en/sql-reference/statements/system.md
@ -264,9 +264,7 @@ Wait until a `ReplicatedMergeTree` table will be synced with other replicas in a
 SYSTEM SYNC REPLICA [db.]replicated_merge_tree_family_table_name
 ```

-After running this statement the `[db.]replicated_merge_tree_family_table_name` fetches commands from
-the common replicated log into its own replication queue, and then the query waits till the replica processes all
-of the fetched commands.
+After running this statement the `[db.]replicated_merge_tree_family_table_name` fetches commands from the common replicated log into its own replication queue, and then the query waits till the replica processes all of the fetched commands.

 ### RESTART REPLICA {#query_language-system-restart-replica}

--- a/docs/ja/development/build.md
+++ b/docs/ja/development/build.md
@ -19,28 +19,17 @@ $ sudo apt-get install git cmake python ninja-build

 古いシステムではcmakeの代わりにcmake3。

-## GCC9のインストール {#install-gcc-10}
+## Clang 11 のインストール

-これを行うにはいくつかの方法があります。
+On Ubuntu/Debian you can use the automatic installation script (check [official webpage](https://apt.llvm.org/))

-### PPAパッケージからインストール {#install-from-a-ppa-package}
-
-``` bash
-$ sudo apt-get install software-properties-common
-$ sudo apt-add-repository ppa:ubuntu-toolchain-r/test
-$ sudo apt-get update
-$ sudo apt-get install gcc-10 g++-10
+```bash
+sudo bash -c "$(wget -O - https://apt.llvm.org/llvm.sh)"
 ```

-### ソースからインスト {#install-from-sources}
-
-見て [utils/ci/build-gcc-from-sources.sh](https://github.com/ClickHouse/ClickHouse/blob/master/utils/ci/build-gcc-from-sources.sh)
-
-## ビルドにGCC9を使用する {#use-gcc-10-for-builds}
-
 ``` bash
-$ export CC=gcc-10
-$ export CXX=g++-10
+$ export CC=clang
+$ export CXX=clang++
 ```

 ## ﾂつｨﾂ姪"ﾂ債ﾂつｹ {#checkout-clickhouse-sources}
@ -76,7 +65,7 @@ $ cd ..
 -   Git（ソースをチェックアウトするためにのみ使用され、ビルドには必要ありません)
 -   CMake3.10以降
 -   忍者（推奨）または作る
-   C++コンパイラ:gcc9またはclang8以降
+-   C++コンパイラ:clang11以降
 -   リンカ:lldまたはgold(古典的なGNU ldは動作しません)
 -   Python(LLVMビルド内でのみ使用され、オプションです)

--- a/docs/ja/development/developer-instruction.md
+++ b/docs/ja/development/developer-instruction.md
@ -133,19 +133,19 @@ ArchまたはGentooを使用する場合は、おそらくCMakeのインスト

 ClickHouseはビルドに複数の外部ライブラリを使用します。 それらのすべては、サブモジュールにあるソースからClickHouseと一緒に構築されているので、別々にインストールする必要はありません。 リストは次の場所で確認できます `contrib`.

-# C++コンパイラ {#c-compiler}
+## C++ Compiler {#c-compiler}

-ClickHouseのビルドには、バージョン9以降のGCCとClangバージョン8以降のコンパイラがサポートされます。
+Compilers Clang starting from version 11 is supported for building ClickHouse.

-公式のYandexビルドは、わずかに優れたパフォーマンスのマシンコードを生成するため、GCCを使用しています（私たちのベンチマークに応じて最大数パーセントの そしてClangは開発のために通常より便利です。 が、当社の継続的インテグレーション（CI)プラットフォームを運チェックのための十数の組み合わせとなります。
+Clang should be used instead of gcc. Though, our continuous integration (CI) platform runs checks for about a dozen of build combinations.

-UBUNTUにGCCをインストールするには: `sudo apt install gcc g++`
+On Ubuntu/Debian you can use the automatic installation script (check [official webpage](https://apt.llvm.org/))

-Gccのバージョンを確認する: `gcc --version`. の場合は下記9その指示に従う。https://clickhouse.tech/docs/ja/development/build/#install-gcc-10.
+```bash
+sudo bash -c "$(wget -O - https://apt.llvm.org/llvm.sh)"
+```

-Mac OS XのビルドはClangでのみサポートされています。 ちょうど実行 `brew install llvm`
-
-Clangを使用する場合は、次のものもインストールできます `libc++` と `lld` あなたがそれが何であるか知っていれば。 を使用して `ccache` また、推奨されます。
+Mac OS X build is also supported. Just run `brew install llvm`

 # 建築プロセス {#the-building-process}

@ -158,13 +158,6 @@ ClickHouseを構築する準備ができたので、別のディレクトリを

 中の間 `build` cmakeを実行してビルドを構成します。 最初の実行の前に、コンパイラ（この例ではバージョン9gccコンパイラ）を指定する環境変数を定義する必要があります。

-Linux:
-
-    export CC=gcc-10 CXX=g++-10
-    cmake ..
-
-Mac OS X:
-
    export CC=clang CXX=clang++
    cmake ..

--- a/docs/ru/development/developer-instruction.md
+++ b/docs/ru/development/developer-instruction.md
@ -136,18 +136,18 @@ ClickHouse использует для сборки некоторое коли

 ## Компилятор C++ {#kompiliator-c}

-В качестве компилятора C++ поддерживается GCC начиная с версии 9 или Clang начиная с версии 8.
+В качестве компилятора C++ поддерживается Clang начиная с версии 11.

-Официальные сборки от Яндекса, на данный момент, используют GCC, так как он генерирует слегка более производительный машинный код (разница в среднем до нескольких процентов по нашим бенчмаркам). Clang обычно более удобен для разработки. Впрочем, наша среда continuous integration проверяет около десятка вариантов сборки.
+Впрочем, наша среда continuous integration проверяет около десятка вариантов сборки, включая gcc, но сборка с помощью gcc непригодна для использования в продакшене.

-Для установки GCC под Ubuntu, выполните: `sudo apt install gcc g++`.
+On Ubuntu/Debian you can use the automatic installation script (check [official webpage](https://apt.llvm.org/))

-Проверьте версию gcc: `gcc --version`. Если версия меньше 10, то следуйте инструкции: https://clickhouse.tech/docs/ru/development/build/#install-gcc-10.
+```bash
+sudo bash -c "$(wget -O - https://apt.llvm.org/llvm.sh)"
+```

 Сборка под Mac OS X поддерживается только для компилятора Clang. Чтобы установить его выполните `brew install llvm`

-Если вы решили использовать Clang, вы также можете установить `libc++` и `lld`, если вы знаете, что это такое. При желании, установите `ccache`.
-
 ## Процесс сборки {#protsess-sborki}

 Теперь вы готовы к сборке ClickHouse. Для размещения собранных файлов, рекомендуется создать отдельную директорию build внутри директории ClickHouse:
@ -158,14 +158,7 @@ ClickHouse использует для сборки некоторое коли
 Вы можете иметь несколько разных директорий (build_release, build_debug) для разных вариантов сборки.

 Находясь в директории build, выполните конфигурацию сборки с помощью CMake.
-Перед первым запуском необходимо выставить переменные окружения, отвечающие за выбор компилятора (в данном примере это - gcc версии 9).
-
-Linux:
-
-    export CC=gcc-10 CXX=g++-10
-    cmake ..
-
-Mac OS X:
+Перед первым запуском необходимо выставить переменные окружения, отвечающие за выбор компилятора.

    export CC=clang CXX=clang++
    cmake ..
--- a/docs/ru/development/style.md
+++ b/docs/ru/development/style.md
@ -747,7 +747,7 @@ The dictionary is configured incorrectly.
 Есть два основных варианта проверки на такие ошибки:

 * Исключение с кодом `LOGICAL_ERROR`. Его можно использовать для важных проверок, которые делаются в том числе в релизной сборке.
-* `assert`. Такие условия не проверяются в релизной сборке, можно использовать для тяжёлых и опциональных проверок.	
+* `assert`. Такие условия не проверяются в релизной сборке, можно использовать для тяжёлых и опциональных проверок.

 Пример сообщения, у которого должен быть код `LOGICAL_ERROR`:
 `Block header is inconsistent with Chunk in ICompicatedProcessor::munge(). It is a bug!`
@ -780,7 +780,7 @@ The dictionary is configured incorrectly.

 **2.** Язык - C++20 (см. список доступных [C++20 фич](https://en.cppreference.com/w/cpp/compiler_support#C.2B.2B20_features)).

-**3.** Компилятор - `gcc`. На данный момент (август 2020), код собирается версией 9.3. (Также код может быть собран `clang` версий 10 и 9)
+**3.** Компилятор - `clang`. На данный момент (апрель 2021), код собирается версией 11. (Также код может быть собран `gcc` версии 10, но такая сборка не тестируется и непригодна для продакшена).

 Используется стандартная библиотека (реализация `libc++`).

--- a/docs/ru/operations/settings/settings.md
+++ b/docs/ru/operations/settings/settings.md
@ -844,8 +844,6 @@ SELECT type, query FROM system.query_log WHERE log_comment = 'log_comment test'

 Значение по умолчанию: количество процессорных ядер без учёта Hyper-Threading.

-Если на сервере обычно исполняется менее одного запроса SELECT одновременно, то выставите этот параметр в значение чуть меньше количества реальных процессорных ядер.
-
 Для запросов, которые быстро завершаются из-за LIMIT-а, имеет смысл выставить max_threads поменьше. Например, если нужное количество записей находится в каждом блоке, то при max_threads = 8 будет считано 8 блоков, хотя достаточно было прочитать один.

 Чем меньше `max_threads`, тем меньше будет использоваться оперативки.
--- a/docs/ru/operations/system-tables/replication_queue.md
+++ b/docs/ru/operations/system-tables/replication_queue.md
@ -14,7 +14,17 @@

 -   `node_name` ([String](../../sql-reference/data-types/string.md)) — имя узла в ZooKeeper.

-   `type` ([String](../../sql-reference/data-types/string.md)) — тип задачи в очереди: `GET_PARTS`, `MERGE_PARTS`, `DETACH_PARTS`, `DROP_PARTS` или `MUTATE_PARTS`.
+-   `type` ([String](../../sql-reference/data-types/string.md)) — тип задачи в очереди:
+
+    -   `GET_PART` — скачать кусок с другой реплики.
+    -   `ATTACH_PART` — присоединить кусок. Задача может быть выполнена и с куском из нашей собственной реплики (если он находится в папке `detached`). Эта задача практически идентична задаче `GET_PART`, лишь немного оптимизирована.
+    -   `MERGE_PARTS` — выполнить слияние кусков.
+    -   `DROP_RANGE` — удалить куски в партициях из указнного диапазона.
+    -   `CLEAR_COLUMN` — удалить указанный столбец из указанной партиции. Примечание: не используется с 20.4.
+    -   `CLEAR_INDEX` — удалить указанный индекс из указанной партиции. Примечание: не используется с 20.4. 
+    -   `REPLACE_RANGE` — удалить указанный диапазон кусков и заменить их на новые.
+    -   `MUTATE_PART` — применить одну или несколько мутаций к куску.
+    -   `ALTER_METADATA` — применить изменения структуры таблицы в результате запросов с выражением `ALTER`.

 -   `create_time` ([Datetime](../../sql-reference/data-types/datetime.md)) — дата и время отправки задачи на выполнение.

@ -77,4 +87,3 @@ last_postpone_time:     1970-01-01 03:00:00
 **Смотрите также**

 -   [Управление таблицами ReplicatedMergeTree](../../sql-reference/statements/system.md#query-language-system-replicated)
-
--- a/docs/ru/operations/system-tables/trace_log.md
+++ b/docs/ru/operations/system-tables/trace_log.md
@ -18,10 +18,12 @@ ClickHouse создает эту таблицу когда утсановлен

        Во время соединения с сервером через `clickhouse-client`, вы видите строку похожую на `Connected to ClickHouse server version 19.18.1 revision 54429.`. Это поле содержит номер после `revision`, но не содержит строку после `version`.

-   `timer_type`([Enum8](../../sql-reference/data-types/enum.md)) — тип таймера:
+-   `trace_type`([Enum8](../../sql-reference/data-types/enum.md)) — тип трассировки:

-        - `Real` означает wall-clock время.
-        - `CPU` означает относительное CPU время.
+    -   `Real` — сбор трассировок стека адресов вызова по времени wall-clock.
+    -   `CPU` — сбор трассировок стека адресов вызова по времени CPU.
+    -   `Memory` — сбор выделенной памяти, когда ее размер превышает относительный инкремент.
+    -   `MemorySample` — сбор случайно выделенной памяти.

 -   `thread_number`([UInt32](../../sql-reference/data-types/int-uint.md)) — идентификатор треда.

--- a/docs/ru/sql-reference/aggregate-functions/combinators.md
+++ b/docs/ru/sql-reference/aggregate-functions/combinators.md
@ -27,6 +27,40 @@ toc_title: "Комбинаторы агрегатных функций"

 Комбинаторы -If и -Array можно сочетать. При этом, должен сначала идти Array, а потом If. Примеры: `uniqArrayIf(arr, cond)`, `quantilesTimingArrayIf(level1, level2)(arr, cond)`. Из-за такого порядка получается, что аргумент cond не должен быть массивом.

+## -SimpleState {#agg-functions-combinator-simplestate}
+
+При использовании этого комбинатора агрегатная функция возвращает то же значение, но типа [SimpleAggregateFunction(...)](../../sql-reference/data-types/simpleaggregatefunction.md). Текущее значение функции может храниться в таблице для последующей работы с таблицами семейства [AggregatingMergeTree](../../engines/table-engines/mergetree-family/aggregatingmergetree.md).
+
+**Синтаксис**
+
+``` sql
+<aggFunction>SimpleState(x)
+```
+
+**Аргументы**
+
+-   `x` — параметры агрегатной функции.
+
+**Возвращаемое значение**
+
+Значение агрегатной функции типа `SimpleAggregateFunction(...)`.
+
+**Пример**
+
+Запрос:
+
+``` sql
+WITH anySimpleState(number) AS c SELECT toTypeName(c), c FROM numbers(1);
+```
+
+Результат:
+
+``` text
+┌─toTypeName(c)────────────────────────┬─c─┐
+│ SimpleAggregateFunction(any, UInt64) │ 0 │
+└──────────────────────────────────────┴───┘
+```
+
 ## -State {#state}

 В случае применения этого комбинатора, агрегатная функция возвращает не готовое значение (например, в случае функции [uniq](reference/uniq.md#agg_function-uniq) — количество уникальных значений), а промежуточное состояние агрегации (например, в случае функции `uniq` — хэш-таблицу для расчёта количества уникальных значений), которое имеет тип `AggregateFunction(...)` и может использоваться для дальнейшей обработки или может быть сохранено в таблицу для последующей доагрегации.
@ -247,4 +281,3 @@ FROM people
 │ [3,2]  │ [11.5,12.949999809265137] │
 └────────┴───────────────────────────┘
 ```
-
--- a/docs/ru/sql-reference/data-types/simpleaggregatefunction.md
+++ b/docs/ru/sql-reference/data-types/simpleaggregatefunction.md
@ -3,6 +3,8 @@
 Хранит только текущее значение агрегатной функции и не сохраняет ее полное состояние, как это делает [`AggregateFunction`](../../sql-reference/data-types/aggregatefunction.md). Такая оптимизация может быть применена к функциям, которые обладают следующим свойством: результат выполнения функции `f` к набору строк `S1 UNION ALL S2` может быть получен путем выполнения `f` к отдельным частям набора строк,
 а затем повторного выполнения `f` к результатам: `f(S1 UNION ALL S2) = f(f(S1) UNION ALL f(S2))`. Это свойство гарантирует, что результатов частичной агрегации достаточно для вычисления комбинированной, поэтому хранить и обрабатывать какие-либо дополнительные данные не требуется.

+Чтобы получить промежуточное значение, обычно используются агрегатные функции с суффиксом [-SimpleState](../../sql-reference/aggregate-functions/combinators.md#agg-functions-combinator-simplestate).
+
 Поддерживаются следующие агрегатные функции:

 -   [`any`](../../sql-reference/aggregate-functions/reference/any.md#agg_function-any)
--- a/docs/ru/sql-reference/functions/other-functions.md
+++ b/docs/ru/sql-reference/functions/other-functions.md
@ -1133,6 +1133,111 @@ SELECT defaultValueOfTypeName('Nullable(Int8)')
 └──────────────────────────────────────────┘
 ```

+## indexHint {#indexhint}
+Возвращает все данные из диапазона, в который попадают данные, соответствующие указанному выражению.
+Переданное выражение не будет вычислено. Выбор диапазона производится по индексу.
+Индекс в ClickHouse разреженный, при чтении диапазона в ответ попадают «лишние» соседние данные.
+
+**Синтаксис**
+
+```sql
+SELECT * FROM table WHERE indexHint(<expression>)
+```
+
+**Возвращаемое значение**
+
+Возвращает диапазон индекса, в котором выполняется заданное условие.
+
+Тип: [Uint8](https://clickhouse.yandex/docs/ru/data_types/int_uint/#diapazony-uint).
+
+**Пример**
+
+Рассмотрим пример с использованием тестовых данных таблицы [ontime](../../getting-started/example-datasets/ontime.md).
+
+Исходная таблица:
+
+```sql
+SELECT count() FROM ontime
+```
+
+```text
+┌─count()─┐
+│ 4276457 │
+└─────────┘
+```
+
+В таблице есть индексы по полям `(FlightDate, (Year, FlightDate))`.
+
+Выполним выборку по дате, где индекс не используется.
+
+Запрос:
+
+```sql
+SELECT FlightDate AS k, count() FROM ontime GROUP BY k ORDER BY k
+```
+
+ClickHouse обработал всю таблицу (`Processed 4.28 million rows`).
+
+Результат:
+
+```text
+┌──────────k─┬─count()─┐
+│ 2017-01-01 │   13970 │
+│ 2017-01-02 │   15882 │
+........................
+│ 2017-09-28 │   16411 │
+│ 2017-09-29 │   16384 │
+│ 2017-09-30 │   12520 │
+└────────────┴─────────┘
+```
+
+Для подключения индекса выбираем конкретную дату.
+
+Запрос:
+
+```sql
+SELECT FlightDate AS k, count() FROM ontime WHERE k = '2017-09-15' GROUP BY k ORDER BY k
+```
+
+При использовании индекса ClickHouse обработал значительно меньшее количество строк (`Processed 32.74 thousand rows`).
+
+Результат:
+
+```text
+┌──────────k─┬─count()─┐
+│ 2017-09-15 │   16428 │
+└────────────┴─────────┘
+```
+
+Передадим в функцию `indexHint` выражение `k = '2017-09-15'`.
+
+Запрос:
+
+```sql
+SELECT
+    FlightDate AS k,
+    count()
+FROM ontime
+WHERE indexHint(k = '2017-09-15')
+GROUP BY k
+ORDER BY k ASC
+```
+
+ClickHouse применил индекс по аналогии с примером выше (`Processed 32.74 thousand rows`).
+Выражение `k = '2017-09-15'` не используется при формировании результата.
+Функция `indexHint` позволяет увидеть соседние данные.
+
+Результат:
+
+```text
+┌──────────k─┬─count()─┐
+│ 2017-09-14 │    7071 │
+│ 2017-09-15 │   16428 │
+│ 2017-09-16 │    1077 │
+│ 2017-09-30 │    8167 │
+└────────────┴─────────┘
+```
+
 ## replicate {#other-functions-replicate}

 Создает массив, заполненный одним значением.
--- a/docs/ru/sql-reference/statements/alter/partition.md
+++ b/docs/ru/sql-reference/statements/alter/partition.md
@ -38,7 +38,7 @@ ALTER TABLE mt DETACH PART 'all_2_2_0';

 После того как запрос будет выполнен, вы сможете производить любые операции с данными в директории `detached`. Например, можно удалить их из файловой системы.

-Запрос реплицируется — данные будут перенесены в директорию `detached` и забыты на всех репликах. Обратите внимание, запрос может быть отправлен только на реплику-лидер. Чтобы узнать, является ли реплика лидером, выполните запрос `SELECT` к системной таблице [system.replicas](../../../operations/system-tables/replicas.md#system_tables-replicas). Либо можно выполнить запрос `DETACH` на всех репликах — тогда на всех репликах, кроме реплики-лидера, запрос вернет ошибку.
+Запрос реплицируется — данные будут перенесены в директорию `detached` и забыты на всех репликах. Обратите внимание, запрос может быть отправлен только на реплику-лидер. Чтобы узнать, является ли реплика лидером, выполните запрос `SELECT` к системной таблице [system.replicas](../../../operations/system-tables/replicas.md#system_tables-replicas). Либо можно выполнить запрос `DETACH` на всех репликах — тогда на всех репликах, кроме реплик-лидеров (поскольку допускается несколько лидеров), запрос вернет ошибку.

 ## DROP PARTITION\|PART {#alter_drop-partition}

@ -83,9 +83,13 @@ ALTER TABLE visits ATTACH PART 201901_2_2_0;

 Как корректно задать имя партиции или куска, см. в разделе [Как задавать имя партиции в запросах ALTER](#alter-how-to-specify-part-expr).

-Этот запрос реплицируется. Реплика-иницатор проверяет, есть ли данные в директории `detached`. Если данные есть, то запрос проверяет их целостность. В случае успеха данные добавляются в таблицу. Все остальные реплики загружают данные с реплики-инициатора запроса.
+Этот запрос реплицируется. Реплика-иницатор проверяет, есть ли данные в директории `detached`.
+Если данные есть, то запрос проверяет их целостность. В случае успеха данные добавляются в таблицу.

-Это означает, что вы можете разместить данные в директории `detached` на одной реплике и с помощью запроса `ALTER ... ATTACH` добавить их в таблицу на всех репликах.
+Если реплика, не являющаяся инициатором запроса, получив команду присоединения, находит кусок с правильными контрольными суммами в своей собственной папке `detached`, она присоединяет данные, не скачивая их с других реплик.
+Если нет куска с правильными контрольными суммами, данные загружаются из любой реплики, имеющей этот кусок.
+
+Вы можете поместить данные в директорию `detached` на одной реплике и с помощью запроса `ALTER ... ATTACH` добавить их в таблицу на всех репликах.

 ## ATTACH PARTITION FROM {#alter_attach-partition-from}

@ -93,7 +97,8 @@ ALTER TABLE visits ATTACH PART 201901_2_2_0;
 ALTER TABLE table2 ATTACH PARTITION partition_expr FROM table1
 ```

-Копирует партицию из таблицы `table1` в таблицу `table2` и добавляет к существующим данным `table2`. Данные из `table1` не удаляются.
+Копирует партицию из таблицы `table1` в таблицу `table2`.
+Обратите внимание, что данные не удаляются ни из `table1`, ни из `table2`.

 Следует иметь в виду:

@ -305,4 +310,3 @@ OPTIMIZE TABLE table_not_partitioned PARTITION tuple() FINAL;
 `IN PARTITION` указывает на партицию, для которой применяются выражения [UPDATE](../../../sql-reference/statements/alter/update.md#alter-table-update-statements) или [DELETE](../../../sql-reference/statements/alter/delete.md#alter-mutations) в результате запроса `ALTER TABLE`. Новые куски создаются только в указанной партиции. Таким образом, `IN PARTITION` помогает снизить нагрузку, когда таблица разбита на множество партиций, а вам нужно обновить данные лишь точечно.

 Примеры запросов `ALTER ... PARTITION` можно посмотреть в тестах: [`00502_custom_partitioning_local`](https://github.com/ClickHouse/ClickHouse/blob/master/tests/queries/0_stateless/00502_custom_partitioning_local.sql) и [`00502_custom_partitioning_replicated_zookeeper`](https://github.com/ClickHouse/ClickHouse/blob/master/tests/queries/0_stateless/00502_custom_partitioning_replicated_zookeeper.sql).
-
--- a/docs/ru/sql-reference/statements/system.md
+++ b/docs/ru/sql-reference/statements/system.md
@ -204,6 +204,7 @@ SYSTEM STOP MOVES [[db.]merge_tree_family_table_name]
 ClickHouse может управлять фоновыми процессами связанными c репликацией в таблицах семейства [ReplicatedMergeTree](../../engines/table-engines/mergetree-family/replacingmergetree.md).

 ### STOP FETCHES {#query_language-system-stop-fetches}
+
 Позволяет остановить фоновые процессы синхронизации новыми вставленными кусками данных с другими репликами в кластере для таблиц семейства `ReplicatedMergeTree`:
 Всегда возвращает `Ok.` вне зависимости от типа таблицы и даже если таблица или база данных не существет.

@ -212,6 +213,7 @@ SYSTEM STOP FETCHES [[db.]replicated_merge_tree_family_table_name]
 ```

 ### START FETCHES {#query_language-system-start-fetches}
+
 Позволяет запустить фоновые процессы синхронизации новыми вставленными кусками данных с другими репликами в кластере для таблиц семейства `ReplicatedMergeTree`:
 Всегда возвращает `Ok.` вне зависимости от типа таблицы и даже если таблица или база данных не существет.

@ -220,6 +222,7 @@ SYSTEM START FETCHES [[db.]replicated_merge_tree_family_table_name]
 ```

 ### STOP REPLICATED SENDS {#query_language-system-start-replicated-sends}
+
 Позволяет остановить фоновые процессы отсылки новых вставленных кусков данных другим репликам в кластере для таблиц семейства `ReplicatedMergeTree`:

 ``` sql
@ -227,6 +230,7 @@ SYSTEM STOP REPLICATED SENDS [[db.]replicated_merge_tree_family_table_name]
 ```

 ### START REPLICATED SENDS {#query_language-system-start-replicated-sends}
+
 Позволяет запустить фоновые процессы отсылки новых вставленных кусков данных другим репликам в кластере для таблиц семейства `ReplicatedMergeTree`:

 ``` sql
@ -234,6 +238,7 @@ SYSTEM START REPLICATED SENDS [[db.]replicated_merge_tree_family_table_name]
 ```

 ### STOP REPLICATION QUEUES {#query_language-system-stop-replication-queues}
+
 Останавливает фоновые процессы разбора заданий из очереди репликации которая хранится в Zookeeper для таблиц семейства `ReplicatedMergeTree`. Возможные типы заданий - merges, fetches, mutation, DDL запросы с ON CLUSTER: 

 ``` sql
@ -241,6 +246,7 @@ SYSTEM STOP REPLICATION QUEUES [[db.]replicated_merge_tree_family_table_name]
 ```

 ### START REPLICATION QUEUES {#query_language-system-start-replication-queues}
+
 Запускает фоновые процессы разбора заданий из очереди репликации которая хранится в Zookeeper для таблиц семейства `ReplicatedMergeTree`. Возможные типы заданий - merges, fetches, mutation, DDL запросы с ON CLUSTER: 

 ``` sql
@ -248,20 +254,24 @@ SYSTEM START REPLICATION QUEUES [[db.]replicated_merge_tree_family_table_name]
 ```

 ### SYNC REPLICA {#query_language-system-sync-replica}
+
 Ждет когда таблица семейства `ReplicatedMergeTree` будет синхронизирована с другими репликами в кластере, будет работать до достижения `receive_timeout`, если синхронизация для таблицы отключена в настоящий момент времени:  

 ``` sql
 SYSTEM SYNC REPLICA [db.]replicated_merge_tree_family_table_name
 ```

+После выполнения этого запроса таблица `[db.]replicated_merge_tree_family_table_name` синхронизирует команды из общего реплицированного лога в свою собственную очередь репликации. Затем запрос ждет, пока реплика не обработает все синхронизированные команды.
+
 ### RESTART REPLICA {#query_language-system-restart-replica}
-Реинициализация состояния Zookeeper сессий для таблицы семейства `ReplicatedMergeTree`, сравнивает текущее состояние с тем что хранится в Zookeeper как источник правды и добавляет задачи Zookeeper очередь если необходимо  
-Инициализация очереди репликации на основе данных ZooKeeper, происходит так же как при attach table. На короткое время таблица станет недоступной для любых операций.
+
+Реинициализация состояния Zookeeper-сессий для таблицы семейства `ReplicatedMergeTree`. Сравнивает текущее состояние с тем, что хранится в Zookeeper, как источник правды, и добавляет задачи в очередь репликации в Zookeeper, если необходимо.
+Инициализация очереди репликации на основе данных ZooKeeper происходит так же, как при attach table. На короткое время таблица станет недоступной для любых операций.

 ``` sql
 SYSTEM RESTART REPLICA [db.]replicated_merge_tree_family_table_name
 ```

 ### RESTART REPLICAS {#query_language-system-restart-replicas}
-Реинициализация состояния Zookeeper сессий для всех `ReplicatedMergeTree` таблиц, сравнивает текущее состояние с тем что хранится в Zookeeper как источник правды и добавляет задачи Zookeeper очередь если необходимо

+Реинициализация состояния ZooKeeper-сессий для всех `ReplicatedMergeTree` таблиц. Сравнивает текущее состояние реплики с тем, что хранится в ZooKeeper, как c источником правды, и добавляет задачи в очередь репликации в ZooKeeper, если необходимо.
--- a/docs/zh/development/build.md
+++ b/docs/zh/development/build.md
@ -35,28 +35,12 @@ sudo apt-get install git cmake ninja-build
 或cmake3而不是旧系统上的cmake。
 或者在早期版本的系统中用 cmake3 替代 cmake

-## 安装 GCC 10 {#an-zhuang-gcc-10}
+## 安装 Clang

-有几种方法可以做到这一点。
+On Ubuntu/Debian you can use the automatic installation script (check [official webpage](https://apt.llvm.org/))

-### 安装 PPA 包 {#an-zhuang-ppa-bao}
-
-``` bash
-sudo apt-get install software-properties-common
-sudo apt-add-repository ppa:ubuntu-toolchain-r/test
-sudo apt-get update
-sudo apt-get install gcc-10 g++-10
-```
-
-### 源码安装 gcc {#yuan-ma-an-zhuang-gcc}
-
-请查看 [utils/ci/build-gcc-from-sources.sh](https://github.com/ClickHouse/ClickHouse/blob/master/utils/ci/build-gcc-from-sources.sh)
-
-## 使用 GCC 10 来编译 {#shi-yong-gcc-10-lai-bian-yi}
-
-``` bash
-export CC=gcc-10
-export CXX=g++-10
+```bash
+sudo bash -c "$(wget -O - https://apt.llvm.org/llvm.sh)"
 ```

 ## 拉取 ClickHouse 源码 {#la-qu-clickhouse-yuan-ma-1}
--- a/docs/zh/development/developer-instruction.md
+++ b/docs/zh/development/developer-instruction.md
@ -123,17 +123,13 @@ ClickHouse使用多个外部库进行构建。大多数外部库不需要单独

 # C++ 编译器 {#c-bian-yi-qi}

-GCC编译器从版本9开始，以及Clang版本\>=8都可支持构建ClickHouse。
+We support clang starting from version 11.

-Yandex官方当前使用GCC构建ClickHouse，因为它生成的机器代码性能较好（根据测评，最多可以相差几个百分点）。Clang通常可以更加便捷的开发。我们的持续集成（CI）平台会运行大约十二种构建组合的检查。
+On Ubuntu/Debian you can use the automatic installation script (check [official webpage](https://apt.llvm.org/))

-在Ubuntu上安装GCC，请执行：`sudo apt install gcc g++`
-
-请使用`gcc --version`查看gcc的版本。如果gcc版本低于9，请参考此处的指示：https://clickhouse.tech/docs/zh/development/build/#an-zhuang-gcc-10 。
-
-在Mac OS X上安装GCC，请执行：`brew install gcc`
-
-如果您决定使用Clang，还可以同时安装 `libc++`以及`lld`，前提是您也熟悉它们。此外，也推荐使用`ccache`。
+```bash
+sudo bash -c "$(wget -O - https://apt.llvm.org/llvm.sh)"
+```

 # 构建的过程 {#gou-jian-de-guo-cheng}

@ -146,7 +142,7 @@ Yandex官方当前使用GCC构建ClickHouse，因为它生成的机器代码性

 在`build`目录下，通过运行CMake配置构建。 在第一次运行之前，请定义用于指定编译器的环境变量（本示例中为gcc 9 编译器）。

-    export CC=gcc-10 CXX=g++-10
+    export CC=clang CXX=clang++
    cmake ..

 `CC`变量指代C的编译器（C Compiler的缩写），而`CXX`变量指代要使用哪个C++编译器进行编译。
--- a/docs/zh/development/style.md
+++ b/docs/zh/development/style.md
@ -696,7 +696,7 @@ auto s = std::string{"Hello"};

 **2.** 语言： C++20.

-**3.** 编译器： `gcc`。 此时（2020年08月），代码使用9.3版编译。（它也可以使用`clang 8` 编译）
+**3.** 编译器： `clang`。 此时（2021年03月），代码使用11版编译。（它也可以使用`gcc` 编译 but it is not suitable for production）

 使用标准库 (`libc++`)。

--- a/docs/zh/sql-reference/functions/other-functions.md
+++ b/docs/zh/sql-reference/functions/other-functions.md
@ -477,6 +477,103 @@ FROM

    1 rows in set. Elapsed: 0.002 sec.

+
+## indexHint  {#indexhint}
+输出符合索引选择范围内的所有数据，同时不实用参数中的表达式进行过滤。
+
+传递给函数的表达式参数将不会被计算，但ClickHouse使用参数中的表达式进行索引过滤。
+
+**返回值**
+
+- 1。
+
+**示例**
+
+这是一个包含[ontime](../../getting-started/example-datasets/ontime.md)测试数据集的测试表。
+
+```
+SELECT count() FROM ontime
+
+┌─count()─┐
+│ 4276457 │
+└─────────┘
+```
+
+该表使用`(FlightDate, (Year, FlightDate))`作为索引。
+
+对该表进行如下的查询：
+
+```
+:) SELECT FlightDate AS k, count() FROM ontime GROUP BY k ORDER BY k
+
+SELECT
+    FlightDate AS k,
+    count()
+FROM ontime
+GROUP BY k
+ORDER BY k ASC
+
+┌──────────k─┬─count()─┐
+│ 2017-01-01 │   13970 │
+│ 2017-01-02 │   15882 │
+........................
+│ 2017-09-28 │   16411 │
+│ 2017-09-29 │   16384 │
+│ 2017-09-30 │   12520 │
+└────────────┴─────────┘
+
+273 rows in set. Elapsed: 0.072 sec. Processed 4.28 million rows, 8.55 MB (59.00 million rows/s., 118.01 MB/s.)
+```
+
+在这个查询中，由于没有使用索引，所以ClickHouse将处理整个表的所有数据(`Processed 4.28 million rows`)。使用下面的查询尝试使用索引进行查询：
+
+```
+:) SELECT FlightDate AS k, count() FROM ontime WHERE k = '2017-09-15' GROUP BY k ORDER BY k
+
+SELECT
+    FlightDate AS k,
+    count()
+FROM ontime
+WHERE k = '2017-09-15'
+GROUP BY k
+ORDER BY k ASC
+
+┌──────────k─┬─count()─┐
+│ 2017-09-15 │   16428 │
+└────────────┴─────────┘
+
+1 rows in set. Elapsed: 0.014 sec. Processed 32.74 thousand rows, 65.49 KB (2.31 million rows/s., 4.63 MB/s.)
+```
+
+在最后一行的显示中，通过索引ClickHouse处理的行数明显减少（`Processed 32.74 thousand rows`）。
+
+现在将表达式`k = '2017-09-15'`传递给`indexHint`函数：
+
+```
+:) SELECT FlightDate AS k, count() FROM ontime WHERE indexHint(k = '2017-09-15') GROUP BY k ORDER BY k
+
+SELECT
+    FlightDate AS k,
+    count()
+FROM ontime
+WHERE indexHint(k = '2017-09-15')
+GROUP BY k
+ORDER BY k ASC
+
+┌──────────k─┬─count()─┐
+│ 2017-09-14 │    7071 │
+│ 2017-09-15 │   16428 │
+│ 2017-09-16 │    1077 │
+│ 2017-09-30 │    8167 │
+└────────────┴─────────┘
+
+4 rows in set. Elapsed: 0.004 sec. Processed 32.74 thousand rows, 65.49 KB (8.97 million rows/s., 17.94 MB/s.)
+```
+
+对于这个请求，根据ClickHouse显示ClickHouse与上一次相同的方式应用了索引（`Processed 32.74 thousand rows`）。但是，最终返回的结果集中并没有根据`k = '2017-09-15'`表达式进行过滤结果。
+
+由于ClickHouse中使用稀疏索引，因此在读取范围时（本示例中为相邻日期），"额外"的数据将包含在索引结果中。使用`indexHint`函数可以查看到它们。
+
 ## 复制 {#replicate}

 使用单个值填充一个数组。
--- a/programs/CMakeLists.txt
+++ b/programs/CMakeLists.txt
@ -33,8 +33,12 @@ option (ENABLE_CLICKHOUSE_OBFUSCATOR "Table data obfuscator (convert real data t
    ${ENABLE_CLICKHOUSE_ALL})

 # https://clickhouse.tech/docs/en/operations/utilities/odbc-bridge/
-option (ENABLE_CLICKHOUSE_ODBC_BRIDGE "HTTP-server working like a proxy to ODBC driver"
-    ${ENABLE_CLICKHOUSE_ALL})
+if (ENABLE_ODBC)
+    option (ENABLE_CLICKHOUSE_ODBC_BRIDGE "HTTP-server working like a proxy to ODBC driver"
+        ${ENABLE_CLICKHOUSE_ALL})
+else ()
+    option (ENABLE_CLICKHOUSE_ODBC_BRIDGE "HTTP-server working like a proxy to ODBC driver" OFF)
+endif ()

 option (ENABLE_CLICKHOUSE_LIBRARY_BRIDGE "HTTP-server working like a proxy to Library dictionary source"
    ${ENABLE_CLICKHOUSE_ALL})
--- a/programs/server/.gitignore
+++ b/programs/server/.gitignore
@ -1,8 +1,11 @@
-/access
-/dictionaries_lib
-/flags
-/format_schemas
+/metadata
 /metadata_dropped
+/data
+/store
+/access
+/flags
+/dictionaries_lib
+/format_schemas
 /preprocessed_configs
 /shadow
 /tmp
--- a/programs/server/data/.gitignore
+++ b/programs/server/data/.gitignore
@ -1,3 +0,0 @@
-*.txt
-*.dat
-*.idx
--- a/programs/server/metadata/.gitignore
+++ b/programs/server/metadata/.gitignore
@ -1 +0,0 @@
-*.sql
--- a/src/AggregateFunctions/AggregateFunctionDeltaSum.h
+++ b/src/AggregateFunctions/AggregateFunctionDeltaSum.h
@ -79,7 +79,7 @@ public:
            place_data->sum += rhs_data->sum + (rhs_data->first - place_data->last);
            place_data->last = rhs_data->last;
        }
-        else if ((rhs_data->last < place_data->first && rhs_data->seen_last && place_data->seen_first))
+        else if ((rhs_data->first < place_data->last && rhs_data->seen_last && place_data->seen_first))
        {
            // In the opposite scenario, the lhs comes after the rhs, e.g. [4, 6] [1, 2]. Since we
            // assume the input interval states are sorted by time, we assume this is a counter
@ -87,9 +87,9 @@ public:
            // rhs last value.

            place_data->sum += rhs_data->sum;
-            place_data->first = rhs_data->first;
+            place_data->last = rhs_data->last;
        }
-        else if (rhs_data->seen_first)
+        else if (rhs_data->seen_first && !place_data->seen_first)
        {
            // If we're here then the lhs is an empty state and the rhs does have some state, so
            // we'll just take that state.
--- a/src/Client/MultiplexedConnections.cpp
+++ b/src/Client/MultiplexedConnections.cpp
@ -13,6 +13,7 @@ namespace ErrorCodes
    extern const int MISMATCH_REPLICAS_DATA_SOURCES;
    extern const int NO_AVAILABLE_REPLICA;
    extern const int TIMEOUT_EXCEEDED;
+    extern const int UNKNOWN_PACKET_FROM_SERVER;
 }


@ -278,7 +279,22 @@ Packet MultiplexedConnections::receivePacketUnlocked(AsyncCallback async_callbac
    Packet packet;
    {
        AsyncCallbackSetter async_setter(current_connection, std::move(async_callback));
-        packet = current_connection->receivePacket();
+
+        try
+        {
+            packet = current_connection->receivePacket();
+        }
+        catch (Exception & e)
+        {
+            if (e.code() == ErrorCodes::UNKNOWN_PACKET_FROM_SERVER)
+            {
+                /// Exception may happen when packet is received, e.g. when got unknown packet.
+                /// In this case, invalidate replica, so that we would not read from it anymore.
+                current_connection->disconnect();
+                invalidateReplica(state);
+            }
+            throw;
+        }
    }

    switch (packet.type)
--- a/src/Core/Block.cpp
+++ b/src/Core/Block.cpp
@ -484,7 +484,7 @@ DataTypes Block::getDataTypes() const


 template <typename ReturnType>
-static ReturnType checkBlockStructure(const Block & lhs, const Block & rhs, const std::string & context_description)
+static ReturnType checkBlockStructure(const Block & lhs, const Block & rhs, const std::string & context_description, bool allow_remove_constants)
 {
    auto on_error = [](const std::string & message [[maybe_unused]], int code [[maybe_unused]])
    {
@ -515,7 +515,16 @@ static ReturnType checkBlockStructure(const Block & lhs, const Block & rhs, cons
        if (!actual.column || !expected.column)
            continue;

-        if (actual.column->getName() != expected.column->getName())
+        const IColumn * actual_column = actual.column.get();
+
+        /// If we allow to remove constants, and expected column is not const, then unwrap actual constant column.
+        if (allow_remove_constants && !isColumnConst(*expected.column))
+        {
+            if (const auto * column_const = typeid_cast<const ColumnConst *>(actual_column))
+                actual_column = &column_const->getDataColumn();
+        }
+
+        if (actual_column->getName() != expected.column->getName())
            return on_error("Block structure mismatch in " + context_description + " stream: different columns:\n"
                + lhs.dumpStructure() + "\n" + rhs.dumpStructure(), ErrorCodes::LOGICAL_ERROR);

@ -537,13 +546,25 @@ static ReturnType checkBlockStructure(const Block & lhs, const Block & rhs, cons

 bool blocksHaveEqualStructure(const Block & lhs, const Block & rhs)
 {
-    return checkBlockStructure<bool>(lhs, rhs, {});
+    return checkBlockStructure<bool>(lhs, rhs, {}, false);
 }


 void assertBlocksHaveEqualStructure(const Block & lhs, const Block & rhs, const std::string & context_description)
 {
-    checkBlockStructure<void>(lhs, rhs, context_description);
+    checkBlockStructure<void>(lhs, rhs, context_description, false);
+}
+
+
+bool isCompatibleHeader(const Block & actual, const Block & desired)
+{
+    return checkBlockStructure<bool>(actual, desired, {}, true);
+}
+
+
+void assertCompatibleHeader(const Block & actual, const Block & desired, const std::string & context_description)
+{
+    checkBlockStructure<void>(actual, desired, context_description, true);
 }


--- a/src/Core/Block.h
+++ b/src/Core/Block.h
@ -184,6 +184,12 @@ bool blocksHaveEqualStructure(const Block & lhs, const Block & rhs);
 /// Throw exception when blocks are different.
 void assertBlocksHaveEqualStructure(const Block & lhs, const Block & rhs, const std::string & context_description);

+/// Actual header is compatible to desired if block have equal structure except constants.
+/// It is allowed when column from actual header is constant, but in desired is not.
+/// If both columns are constant, it is checked that they have the same value.
+bool isCompatibleHeader(const Block & actual, const Block & desired);
+void assertCompatibleHeader(const Block & actual, const Block & desired, const std::string & context_description);
+
 /// Calculate difference in structure of blocks and write description into output strings. NOTE It doesn't compare values of constant columns.
 void getBlocksDifference(const Block & lhs, const Block & rhs, std::string & out_lhs_diff, std::string & out_rhs_diff);

--- a/src/Core/Settings.h
+++ b/src/Core/Settings.h
@ -225,6 +225,7 @@ class IColumn;
    /** Settings for testing hedged requests */ \
    M(Milliseconds, sleep_in_send_tables_status_ms, 0, "Time to sleep in sending tables status response in TCPHandler", 0) \
    M(Milliseconds, sleep_in_send_data_ms, 0, "Time to sleep in sending data in TCPHandler", 0) \
+    M(UInt64, unknown_packet_in_send_data, 0, "Send unknown packet instead of data Nth data packet", 0) \
    \
    M(Bool, insert_allow_materialized_columns, 0, "If setting is enabled, Allow materialized columns in INSERT.", 0) \
    M(Seconds, http_connection_timeout, DEFAULT_HTTP_READ_BUFFER_CONNECTION_TIMEOUT, "HTTP connection timeout.", 0) \
--- a/src/DataTypes/DataTypeDateTime.h
+++ b/src/DataTypes/DataTypeDateTime.h
@ -19,9 +19,12 @@ public:
    TimezoneMixin(const TimezoneMixin &) = default;

    const DateLUTImpl & getTimeZone() const { return time_zone; }
+    bool hasExplicitTimeZone() const { return has_explicit_time_zone; }

 protected:
+    /// true if time zone name was provided in data type parameters, false if it's using default time zone.
    bool has_explicit_time_zone;
+
    const DateLUTImpl & time_zone;
    const DateLUTImpl & utc_time_zone;
 };
--- a/src/DataTypes/IDataType.h
+++ b/src/DataTypes/IDataType.h
@ -360,7 +360,8 @@ inline bool isEnum(const DataTypePtr & data_type) { return WhichDataType(data_ty
 inline bool isDecimal(const DataTypePtr & data_type) { return WhichDataType(data_type).isDecimal(); }
 inline bool isTuple(const DataTypePtr & data_type) { return WhichDataType(data_type).isTuple(); }
 inline bool isArray(const DataTypePtr & data_type) { return WhichDataType(data_type).isArray(); }
-inline bool isMap(const DataTypePtr & data_type) {return WhichDataType(data_type).isMap(); }
+inline bool isMap(const DataTypePtr & data_type) { return WhichDataType(data_type).isMap(); }
+inline bool isNothing(const DataTypePtr & data_type) { return WhichDataType(data_type).isNothing(); }

 template <typename T>
 inline bool isUInt8(const T & data_type)
--- a/src/Functions/FunctionCustomWeekToSomething.h
+++ b/src/Functions/FunctionCustomWeekToSomething.h
@ -5,7 +5,6 @@
 #include <Functions/CustomWeekTransforms.h>
 #include <Functions/IFunctionImpl.h>
 #include <Functions/TransformDateTime64.h>
-#include <Functions/extractTimeZoneFromFunctionArguments.h>
 #include <IO/WriteHelpers.h>


--- a/src/Functions/FunctionsConversion.h
+++ b/src/Functions/FunctionsConversion.h
@ -2496,7 +2496,7 @@ private:
        }
    }

-    WrapperType createArrayWrapper(const DataTypePtr & from_type_untyped, const DataTypeArray * to_type) const
+    WrapperType createArrayWrapper(const DataTypePtr & from_type_untyped, const DataTypeArray & to_type) const
    {
        /// Conversion from String through parsing.
        if (checkAndGetDataType<DataTypeString>(from_type_untyped.get()))
@ -2507,24 +2507,23 @@ private:
            };
        }

-        DataTypePtr from_nested_type;
-        DataTypePtr to_nested_type;
        const auto * from_type = checkAndGetDataType<DataTypeArray>(from_type_untyped.get());
-
-        /// get the most nested type
-        if (from_type && to_type)
+        if (!from_type)
        {
-            from_nested_type = from_type->getNestedType();
-            to_nested_type = to_type->getNestedType();
-
-            from_type = checkAndGetDataType<DataTypeArray>(from_nested_type.get());
-            to_type = checkAndGetDataType<DataTypeArray>(to_nested_type.get());
+            throw Exception(ErrorCodes::TYPE_MISMATCH,
+                "CAST AS Array can only be perforamed between same-dimensional Array or String types");
        }

-        /// both from_type and to_type should be nullptr now is array types had same dimensions
-        if ((from_type == nullptr) != (to_type == nullptr))
-            throw Exception{"CAST AS Array can only be performed between same-dimensional array types or from String",
-                ErrorCodes::TYPE_MISMATCH};
+        DataTypePtr from_nested_type = from_type->getNestedType();
+
+        /// In query SELECT CAST([] AS Array(Array(String))) from type is Array(Nothing)
+        bool from_empty_array = isNothing(from_nested_type);
+
+        if (from_type->getNumberOfDimensions() != to_type.getNumberOfDimensions() && !from_empty_array)
+            throw Exception(ErrorCodes::TYPE_MISMATCH,
+                "CAST AS Array can only be perforamed between same-dimensional array types");
+
+        const DataTypePtr & to_nested_type = to_type.getNestedType();

        /// Prepare nested type conversion
        const auto nested_function = prepareUnpackDictionaries(from_nested_type, to_nested_type);
@ -3090,14 +3089,12 @@ private:
                return createStringWrapper(from_type);
            case TypeIndex::FixedString:
                return createFixedStringWrapper(from_type, checkAndGetDataType<DataTypeFixedString>(to_type.get())->getN());
-
            case TypeIndex::Array:
-                return createArrayWrapper(from_type, checkAndGetDataType<DataTypeArray>(to_type.get()));
+                return createArrayWrapper(from_type, static_cast<const DataTypeArray &>(*to_type));
            case TypeIndex::Tuple:
                return createTupleWrapper(from_type, checkAndGetDataType<DataTypeTuple>(to_type.get()));
            case TypeIndex::Map:
                return createMapWrapper(from_type, checkAndGetDataType<DataTypeMap>(to_type.get()));
-
            case TypeIndex::AggregateFunction:
                return createAggregateFunctionWrapper(from_type, checkAndGetDataType<DataTypeAggregateFunction>(to_type.get()));
            default:
--- a/src/Functions/extractTimeZoneFromFunctionArguments.cpp
+++ b/src/Functions/extractTimeZoneFromFunctionArguments.cpp
@ -44,9 +44,9 @@ std::string extractTimeZoneNameFromFunctionArguments(const ColumnsWithTypeAndNam

        /// If time zone is attached to an argument of type DateTime.
        if (const auto * type = checkAndGetDataType<DataTypeDateTime>(arguments[datetime_arg_num].type.get()))
-            return type->getTimeZone().getTimeZone();
+            return type->hasExplicitTimeZone() ? type->getTimeZone().getTimeZone() : std::string();
        if (const auto * type = checkAndGetDataType<DataTypeDateTime64>(arguments[datetime_arg_num].type.get()))
-            return type->getTimeZone().getTimeZone();
+            return type->hasExplicitTimeZone() ? type->getTimeZone().getTimeZone() : std::string();

        return {};
    }
--- a/src/Functions/extractTimeZoneFromFunctionArguments.h
+++ b/src/Functions/extractTimeZoneFromFunctionArguments.h
@ -13,6 +13,7 @@ namespace DB
 class Block;

 /// Determine working timezone either from optional argument with time zone name or from time zone in DateTime type of argument.
+/// Returns empty string if default time zone should be used.
 std::string extractTimeZoneNameFromFunctionArguments(
    const ColumnsWithTypeAndName & arguments, size_t time_zone_arg_num, size_t datetime_arg_num);

--- a/src/Functions/indexHint.cpp
+++ b/src/Functions/indexHint.cpp
@ -0,0 +1,70 @@
+#include <Functions/IFunctionImpl.h>
+#include <Functions/FunctionFactory.h>
+#include <DataTypes/DataTypesNumber.h>
+
+
+namespace DB
+{
+
+
+/** The `indexHint` function takes any number of any arguments and always returns one.
+  *
+  * This function has a special meaning (see ExpressionAnalyzer, KeyCondition)
+  * - the expressions inside it are not evaluated;
+  * - but when analyzing the index (selecting ranges for reading), this function is treated the same way,
+  *   as if instead of using it the expression itself would be.
+  *
+  * Example: WHERE something AND indexHint(CounterID = 34)
+  * - do not read or calculate CounterID = 34, but select ranges in which the CounterID = 34 expression can be true.
+  *
+  * The function can be used for debugging purposes, as well as for (hidden from the user) query conversions.
+  */
+class FunctionIndexHint : public IFunction
+{
+public:
+    static constexpr auto name = "indexHint";
+    static FunctionPtr create(ContextPtr)
+    {
+        return std::make_shared<FunctionIndexHint>();
+    }
+
+    bool isVariadic() const override
+    {
+        return true;
+    }
+    size_t getNumberOfArguments() const override
+    {
+        return 0;
+    }
+
+    bool useDefaultImplementationForNulls() const override { return false; }
+
+    bool isSuitableForConstantFolding() const override { return false; }
+
+    String getName() const override
+    {
+        return name;
+    }
+    DataTypePtr getReturnTypeImpl(const DataTypes & /*arguments*/) const override
+    {
+        return std::make_shared<DataTypeUInt8>();
+    }
+
+    ColumnPtr executeImpl(const ColumnsWithTypeAndName &, const DataTypePtr &, size_t input_rows_count) const override
+    {
+        return DataTypeUInt8().createColumnConst(input_rows_count, 1u);
+    }
+
+    ColumnPtr getResultIfAlwaysReturnsConstantAndHasArguments(const ColumnsWithTypeAndName &) const override
+    {
+        return DataTypeUInt8().createColumnConst(1, 1u);
+    }
+};
+
+
+void registerFunctionIndexHint(FunctionFactory & factory)
+{
+    factory.registerFunction<FunctionIndexHint>();
+}
+
+}
--- a/src/Functions/intDiv.cpp
+++ b/src/Functions/intDiv.cpp
@ -39,7 +39,7 @@ struct DivideIntegralByConstantImpl

    static ResultType process(A a, B b) { return Op::template apply<ResultType>(a, b); }

-    static NO_INLINE void vectorConstant(const A * __restrict a_pos, B b, ResultType * __restrict c_pos, size_t size)
+    static void NO_INLINE NO_SANITIZE_UNDEFINED vectorConstant(const A * __restrict a_pos, B b, ResultType * __restrict c_pos, size_t size)
    {
 #pragma GCC diagnostic push
 #pragma GCC diagnostic ignored "-Wsign-compare"
--- a/src/Functions/modulo.cpp
+++ b/src/Functions/modulo.cpp
@ -43,7 +43,7 @@ struct ModuloByConstantImpl

    static ResultType process(A a, B b) { return Op::template apply<ResultType>(a, b); }

-    static void NO_INLINE vectorConstant(const A * __restrict src, B b, ResultType * __restrict dst, size_t size)
+    static void NO_INLINE NO_SANITIZE_UNDEFINED vectorConstant(const A * __restrict src, B b, ResultType * __restrict dst, size_t size)
    {
 #pragma GCC diagnostic push
 #pragma GCC diagnostic ignored "-Wsign-compare"
--- a/src/Functions/registerFunctionsMiscellaneous.cpp
+++ b/src/Functions/registerFunctionsMiscellaneous.cpp
@ -28,6 +28,7 @@ void registerFunctionSleep(FunctionFactory &);
 void registerFunctionSleepEachRow(FunctionFactory &);
 void registerFunctionMaterialize(FunctionFactory &);
 void registerFunctionIgnore(FunctionFactory &);
+void registerFunctionIndexHint(FunctionFactory &);
 void registerFunctionIdentity(FunctionFactory &);
 void registerFunctionArrayJoin(FunctionFactory &);
 void registerFunctionReplicate(FunctionFactory &);
@ -101,6 +102,7 @@ void registerFunctionsMiscellaneous(FunctionFactory & factory)
    registerFunctionSleepEachRow(factory);
    registerFunctionMaterialize(factory);
    registerFunctionIgnore(factory);
+    registerFunctionIndexHint(factory);
    registerFunctionIdentity(factory);
    registerFunctionArrayJoin(factory);
    registerFunctionReplicate(factory);
--- a/src/Functions/ya.make
+++ b/src/Functions/ya.make
@ -303,6 +303,7 @@ SRCS(
    ignore.cpp
    ilike.cpp
    in.cpp
+    indexHint.cpp
    initializeAggregation.cpp
    intDiv.cpp
    intDivOrZero.cpp
--- a/src/Interpreters/ActionsDAG.cpp
+++ b/src/Interpreters/ActionsDAG.cpp
@ -181,7 +181,7 @@ const ActionsDAG::Node & ActionsDAG::addFunction(
        }
    }

-    /// Some functions like ignore() or getTypeName() always return constant result even if arguments are not constant.
+    /// Some functions like ignore(), indexHint() or getTypeName() always return constant result even if arguments are not constant.
    /// We can't do constant folding, but can specify in sample block that function result is constant to avoid
    /// unnecessary materialization.
    if (!node.column && node.function_base->isSuitableForConstantFolding())
--- a/src/Interpreters/ActionsVisitor.cpp
+++ b/src/Interpreters/ActionsVisitor.cpp
@ -811,6 +811,14 @@ void ActionsMatcher::visit(const ASTFunction & node, const ASTPtr & ast, Data &
        }
    }

+    /// A special function `indexHint`. Everything that is inside it is not calculated
+    if (node.name == "indexHint")
+    {
+        // Arguments are removed. We add function instead of constant column to avoid constant folding.
+        data.addFunction(FunctionFactory::instance().get("indexHint", data.getContext()), {}, column_name);
+        return;
+    }
+
    if (node.is_window_function)
    {
        // Also add columns from PARTITION BY and ORDER BY of window functions.
--- a/src/Interpreters/ExpressionAnalyzer.cpp
+++ b/src/Interpreters/ExpressionAnalyzer.cpp
@ -1510,7 +1510,8 @@ ExpressionAnalysisResult::ExpressionAnalysisResult(

        optimize_read_in_order =
            settings.optimize_read_in_order
-            && storage && query.orderBy()
+            && storage
+            && query.orderBy()
            && !query_analyzer.hasAggregation()
            && !query_analyzer.hasWindow()
            && !query.final()
--- a/src/Interpreters/QueryAliasesVisitor.cpp
+++ b/src/Interpreters/QueryAliasesVisitor.cpp
@ -15,15 +15,22 @@ namespace ErrorCodes
    extern const int MULTIPLE_EXPRESSIONS_FOR_ALIAS;
 }

-static String wrongAliasMessage(const ASTPtr & ast, const ASTPtr & prev_ast, const String & alias)
+namespace
 {
-    WriteBufferFromOwnString message;
-    message << "Different expressions with the same alias " << backQuoteIfNeed(alias) << ":\n";
-    formatAST(*ast, message, false, true);
-    message << "\nand\n";
-    formatAST(*prev_ast, message, false, true);
-    message << '\n';
-    return message.str();
+
+    constexpr auto dummy_subquery_name_prefix = "_subquery";
+
+    String wrongAliasMessage(const ASTPtr & ast, const ASTPtr & prev_ast, const String & alias)
+    {
+        WriteBufferFromOwnString message;
+        message << "Different expressions with the same alias " << backQuoteIfNeed(alias) << ":\n";
+        formatAST(*ast, message, false, true);
+        message << "\nand\n";
+        formatAST(*prev_ast, message, false, true);
+        message << '\n';
+        return message.str();
+    }
+
 }


@ -99,7 +106,7 @@ void QueryAliasesMatcher<T>::visit(const ASTSubquery & const_subquery, const AST
        String alias;
        do
        {
-            alias = "_subquery" + std::to_string(++subquery_index);
+            alias = dummy_subquery_name_prefix + std::to_string(++subquery_index);
        }
        while (aliases.count(alias));

@ -124,6 +131,30 @@ void QueryAliasesMatcher<T>::visitOther(const ASTPtr & ast, Data & data)

        aliases[alias] = ast;
    }
+
+    /** QueryAliasesVisitor is executed before ExecuteScalarSubqueriesVisitor.
+        For example we have subquery in our query (SELECT sum(number) FROM numbers(10)).
+
+        After running QueryAliasesVisitor it will be (SELECT sum(number) FROM numbers(10)) as _subquery_1
+        and prefer_alias_to_column_name for this subquery will be true.
+
+        After running ExecuteScalarSubqueriesVisitor it will be converted to (45 as _subquery_1)
+        and prefer_alias_to_column_name for ast literal will be true.
+
+        But if we send such query on remote host with Distributed engine for example we cannot send prefer_alias_to_column_name
+        information for our ast node with query string. And this alias will be dropped because prefer_alias_to_column_name for ASTWIthAlias
+        by default is false.
+
+        It is imporant that subquery can be converted to literal during ExecuteScalarSubqueriesVisitor.
+        And code below check if we previously set for subquery alias as _subquery, and if it is true
+        then set prefer_alias_to_column_name = true for node that was optimized during ExecuteScalarSubqueriesVisitor.
+     */
+
+    if (auto * ast_with_alias = dynamic_cast<ASTWithAlias *>(ast.get()))
+    {
+        if (startsWith(alias, dummy_subquery_name_prefix))
+            ast_with_alias->prefer_alias_to_column_name = true;
+    }
 }

 /// Explicit template instantiations
--- a/src/Interpreters/RequiredSourceColumnsVisitor.cpp
+++ b/src/Interpreters/RequiredSourceColumnsVisitor.cpp
@ -51,8 +51,10 @@ bool RequiredSourceColumnsMatcher::needChildVisit(const ASTPtr & node, const AST

    if (const auto * f = node->as<ASTFunction>())
    {
+        /// "indexHint" is a special function for index analysis.
+        /// Everything that is inside it is not calculated. See KeyCondition
        /// "lambda" visit children itself.
-        if (f->name == "lambda")
+        if (f->name == "indexHint" || f->name == "lambda")
            return false;
    }

--- a/src/Processors/Formats/Impl/ArrowBlockInputFormat.cpp
+++ b/src/Processors/Formats/Impl/ArrowBlockInputFormat.cpp
@ -24,7 +24,6 @@ namespace ErrorCodes
 ArrowBlockInputFormat::ArrowBlockInputFormat(ReadBuffer & in_, const Block & header_, bool stream_)
    : IInputFormat(header_, in_), stream{stream_}
 {
-    prepareReader();
 }

 Chunk ArrowBlockInputFormat::generate()
@ -35,12 +34,18 @@ Chunk ArrowBlockInputFormat::generate()

    if (stream)
    {
+        if (!stream_reader)
+            prepareReader();
+
        batch_result = stream_reader->Next();
        if (batch_result.ok() && !(*batch_result))
            return res;
    }
    else
    {
+        if (!file_reader)
+            prepareReader();
+
        if (record_batch_current >= record_batch_total)
            return res;

@ -71,7 +76,7 @@ void ArrowBlockInputFormat::resetParser()
        stream_reader.reset();
    else
        file_reader.reset();
-    prepareReader();
+    record_batch_current = 0;
 }

 void ArrowBlockInputFormat::prepareReader()
--- a/src/Processors/Pipe.cpp
+++ b/src/Processors/Pipe.cpp
@ -8,6 +8,7 @@
 #include <Processors/Transforms/ExtremesTransform.h>
 #include <Processors/Formats/IOutputFormat.h>
 #include <Processors/Sources/NullSource.h>
+#include <Columns/ColumnConst.h>

 namespace DB
 {
@ -250,6 +251,47 @@ static Pipes removeEmptyPipes(Pipes pipes)
    return res;
 }

+/// Calculate common header for pipes.
+/// This function is needed only to remove ColumnConst from common header in case if some columns are const, and some not.
+/// E.g. if the first header is `x, const y, const z` and the second is `const x, y, const z`, the common header will be `x, y, const z`.
+static Block getCommonHeader(const Pipes & pipes)
+{
+    Block res;
+
+    for (const auto & pipe : pipes)
+    {
+        if (const auto & header = pipe.getHeader())
+        {
+            res = header;
+            break;
+        }
+    }
+
+    for (const auto & pipe : pipes)
+    {
+        const auto & header = pipe.getHeader();
+        for (size_t i = 0; i < res.columns(); ++i)
+        {
+            /// We do not check that headers are compatible here. Will do it later.
+
+            if (i >= header.columns())
+                break;
+
+            auto & common = res.getByPosition(i).column;
+            const auto & cur = header.getByPosition(i).column;
+
+            /// Only remove const from common header if it is not const for current pipe.
+            if (cur && common && !isColumnConst(*cur))
+            {
+                if (const auto * column_const = typeid_cast<const ColumnConst *>(common.get()))
+                    common = column_const->getDataColumnPtr();
+            }
+        }
+    }
+
+    return res;
+}
+
 Pipe Pipe::unitePipes(Pipes pipes)
 {
    return Pipe::unitePipes(std::move(pipes), nullptr, false);
@ -276,23 +318,12 @@ Pipe Pipe::unitePipes(Pipes pipes, Processors * collected_processors, bool allow
    OutputPortRawPtrs totals;
    OutputPortRawPtrs extremes;
    res.collected_processors = collected_processors;
-    res.header = pipes.front().header;
-    if (allow_empty_header && !res.header)
-    {
-        for (const auto & pipe : pipes)
-        {
-            if (const auto & header = pipe.getHeader())
-            {
-                res.header = header;
-                break;
-            }
-        }
-    }
+    res.header = getCommonHeader(pipes);

    for (auto & pipe : pipes)
    {
        if (!allow_empty_header || pipe.header)
-            assertBlocksHaveEqualStructure(res.header, pipe.header, "Pipe::unitePipes");
+            assertCompatibleHeader(pipe.header, res.header, "Pipe::unitePipes");

        res.processors.insert(res.processors.end(), pipe.processors.begin(), pipe.processors.end());
        res.output_ports.insert(res.output_ports.end(), pipe.output_ports.begin(), pipe.output_ports.end());
--- a/src/Processors/Port.cpp
+++ b/src/Processors/Port.cpp
@ -16,7 +16,7 @@ void connect(OutputPort & output, InputPort & input)
    auto out_name = output.getProcessor().getName();
    auto in_name = input.getProcessor().getName();

-    assertBlocksHaveEqualStructure(input.getHeader(), output.getHeader(), " function connect between " + out_name + " and " + in_name);
+    assertCompatibleHeader(output.getHeader(), input.getHeader(), " function connect between " + out_name + " and " + in_name);

    input.output_port = &output;
    output.input_port = &input;
--- a/src/Processors/QueryPipeline.cpp
+++ b/src/Processors/QueryPipeline.cpp
@ -232,8 +232,6 @@ QueryPipeline QueryPipeline::unitePipelines(
        pipeline.checkInitialized();
        pipeline.pipe.collected_processors = collected_processors;

-        assertBlocksHaveEqualStructure(pipeline.getHeader(), common_header, "QueryPipeline::unitePipelines");
-
        pipes.emplace_back(std::move(pipeline.pipe));

        max_threads += pipeline.max_threads;
--- a/src/Server/TCPHandler.cpp
+++ b/src/Server/TCPHandler.cpp
@ -311,6 +311,8 @@ void TCPHandler::runImpl()
            /// Processing Query
            state.io = executeQuery(state.query, query_context, false, state.stage, may_have_embedded_data);

+            unknown_packet_in_send_data = query_context->getSettingsRef().unknown_packet_in_send_data;
+
            after_check_cancelled.restart();
            after_send_progress.restart();

@ -1472,6 +1474,14 @@ void TCPHandler::sendData(const Block & block)

    try
    {
+        /// For testing hedged requests
+        if (unknown_packet_in_send_data)
+        {
+            --unknown_packet_in_send_data;
+            if (unknown_packet_in_send_data == 0)
+                writeVarUInt(UInt64(-1), *out);
+        }
+
        writeVarUInt(Protocol::Server::Data, *out);
        /// Send external table name (empty name is the main table)
        writeStringBinary("", *out);
--- a/src/Server/TCPHandler.h
+++ b/src/Server/TCPHandler.h
@ -135,6 +135,8 @@ private:
    ContextPtr connection_context;
    ContextPtr query_context;

+    size_t unknown_packet_in_send_data = 0;
+
    /// Streams for reading/writing from/to client connection socket.
    std::shared_ptr<ReadBuffer> in;
    std::shared_ptr<WriteBuffer> out;
--- a/src/Storages/MergeTree/KeyCondition.cpp
+++ b/src/Storages/MergeTree/KeyCondition.cpp
@ -309,11 +309,11 @@ static const std::map<std::string, std::string> inverse_relations = {

 bool isLogicalOperator(const String & func_name)
 {
-    return (func_name == "and" || func_name == "or" || func_name == "not");
+    return (func_name == "and" || func_name == "or" || func_name == "not" || func_name == "indexHint");
 }

 /// The node can be one of:
-///   - Logical operator (AND, OR, NOT)
+///   - Logical operator (AND, OR, NOT and indexHint() - logical NOOP)
 ///   - An "atom" (relational operator, constant, expression)
 ///   - A logical constant expression
 ///   - Any other function
@ -330,7 +330,8 @@ ASTPtr cloneASTWithInversionPushDown(const ASTPtr node, const bool need_inversio

        const auto result_node = makeASTFunction(func->name);

-        if (need_inversion)
+        /// indexHint() is a special case - logical NOOP function
+        if (result_node->name != "indexHint" && need_inversion)
        {
            result_node->name = (result_node->name == "and") ? "or" : "and";
        }
@ -965,6 +966,8 @@ bool KeyCondition::isKeyPossiblyWrappedByMonotonicFunctions(
    {
        const auto & args = (*it)->arguments->children;
        auto func_builder = FunctionFactory::instance().tryGet((*it)->name, context);
+        if (!func_builder)
+            return false;
        ColumnsWithTypeAndName arguments;
        ColumnWithTypeAndName const_arg;
        FunctionWithOptionalConstArg::Kind kind = FunctionWithOptionalConstArg::Kind::NO_CONST;
@ -1277,6 +1280,8 @@ bool KeyCondition::tryParseAtomFromAST(const ASTPtr & node, ContextPtr context,
 bool KeyCondition::tryParseLogicalOperatorFromAST(const ASTFunction * func, RPNElement & out)
 {
    /// Functions AND, OR, NOT.
+    /// Also a special function `indexHint` - works as if instead of calling a function there are just parentheses
+    /// (or, the same thing - calling the function `and` from one argument).
    const ASTs & args = func->arguments->children;

    if (func->name == "not")
@ -1288,7 +1293,7 @@ bool KeyCondition::tryParseLogicalOperatorFromAST(const ASTFunction * func, RPNE
    }
    else
    {
-        if (func->name == "and")
+        if (func->name == "and" || func->name == "indexHint")
            out.function = RPNElement::FUNCTION_AND;
        else if (func->name == "or")
            out.function = RPNElement::FUNCTION_OR;
--- a/src/Storages/MergeTree/MergeTreeDataSelectExecutor.cpp
+++ b/src/Storages/MergeTree/MergeTreeDataSelectExecutor.cpp
@ -39,7 +39,6 @@
 #include <DataTypes/DataTypeUUID.h>
 #include <DataTypes/DataTypesNumber.h>
 #include <Storages/VirtualColumnUtils.h>
-#include <DataStreams/materializeBlock.h>

 namespace ProfileEvents
 {
--- a/src/Storages/MergeTree/MergeTreeIndexSet.cpp
+++ b/src/Storages/MergeTree/MergeTreeIndexSet.cpp
@ -392,7 +392,7 @@ bool MergeTreeIndexConditionSet::operatorFromAST(ASTPtr & node)

        func->name = "__bitSwapLastTwo";
    }
-    else if (func->name == "and")
+    else if (func->name == "and" || func->name == "indexHint")
    {
        auto last_arg = args.back();
        args.pop_back();
@ -448,7 +448,7 @@ bool MergeTreeIndexConditionSet::checkASTUseless(const ASTPtr & node, bool atomi

        const ASTs & args = func->arguments->children;

-        if (func->name == "and")
+        if (func->name == "and" || func->name == "indexHint")
            return checkASTUseless(args[0], atomic) && checkASTUseless(args[1], atomic);
        else if (func->name == "or")
            return checkASTUseless(args[0], atomic) || checkASTUseless(args[1], atomic);
--- a/src/Storages/MergeTree/MergeTreeWhereOptimizer.cpp
+++ b/src/Storages/MergeTree/MergeTreeWhereOptimizer.cpp
@ -339,6 +339,10 @@ bool MergeTreeWhereOptimizer::cannotBeMoved(const ASTPtr & ptr, bool is_final) c
        if ("globalIn" == function_ptr->name
            || "globalNotIn" == function_ptr->name)
            return true;
+
+        /// indexHint is a special function that it does not make sense to transfer to PREWHERE
+        if ("indexHint" == function_ptr->name)
+            return true;
    }
    else if (auto opt_name = IdentifierSemantic::getColumnName(ptr))
    {
--- a/src/Storages/MergeTree/RPNBuilder.h
+++ b/src/Storages/MergeTree/RPNBuilder.h
@ -90,6 +90,8 @@ private:
    bool operatorFromAST(const ASTFunction * func, RPNElement & out)
    {
        /// Functions AND, OR, NOT.
+        /// Also a special function `indexHint` - works as if instead of calling a function there are just parentheses
+        /// (or, the same thing - calling the function `and` from one argument).
        const ASTs & args = typeid_cast<const ASTExpressionList &>(*func->arguments).children;

        if (func->name == "not")
@ -101,7 +103,7 @@ private:
        }
        else
        {
-            if (func->name == "and")
+            if (func->name == "and" || func->name == "indexHint")
                out.function = RPNElement::FUNCTION_AND;
            else if (func->name == "or")
                out.function = RPNElement::FUNCTION_OR;
--- a/src/Storages/ReadInOrderOptimizer.cpp
+++ b/src/Storages/ReadInOrderOptimizer.cpp
@ -44,7 +44,7 @@ InputOrderInfoPtr ReadInOrderOptimizer::getInputOrder(const StorageMetadataPtr &
    int read_direction = required_sort_description.at(0).direction;

    size_t prefix_size = std::min(required_sort_description.size(), sorting_key_columns.size());
-    auto aliase_columns = metadata_snapshot->getColumns().getAliases();
+    auto aliased_columns = metadata_snapshot->getColumns().getAliases();

    for (size_t i = 0; i < prefix_size; ++i)
    {
@ -55,13 +55,18 @@ InputOrderInfoPtr ReadInOrderOptimizer::getInputOrder(const StorageMetadataPtr &
        ///  or in some simple cases when order key element is wrapped into monotonic function.
        auto apply_order_judge = [&] (const ExpressionActions::Actions & actions, const String & sort_column)
        {
+            /// If required order depend on collation, it cannot be matched with primary key order.
+            /// Because primary keys cannot have collations.
+            if (required_sort_description[i].collator)
+                return false;
+
            int current_direction = required_sort_description[i].direction;
-            /// For the path:  order by (sort_column, ...)
+            /// For the path: order by (sort_column, ...)
            if (sort_column == sorting_key_columns[i] && current_direction == read_direction)
            {
                return true;
            }
-            /// For the path:  order by (function(sort_column), ...)
+            /// For the path: order by (function(sort_column), ...)
            /// Allow only one simple monotonic functions with one argument
            /// Why not allow multi monotonic functions?
            else
@ -125,7 +130,7 @@ InputOrderInfoPtr ReadInOrderOptimizer::getInputOrder(const StorageMetadataPtr &
        /// currently we only support alias column without any function wrapper
        /// ie: `order by aliased_column` can have this optimization, but `order by function(aliased_column)` can not.
        /// This suits most cases.
-        if (context->getSettingsRef().optimize_respect_aliases && aliase_columns.contains(required_sort_description[i].column_name))
+        if (context->getSettingsRef().optimize_respect_aliases && aliased_columns.contains(required_sort_description[i].column_name))
        {
            auto column_expr = metadata_snapshot->getColumns().get(required_sort_description[i].column_name).default_desc.expression->clone();
            replaceAliasColumnsInQuery(column_expr, metadata_snapshot->getColumns(), forbidden_columns, context);
--- a/src/Storages/StorageReplicatedMergeTree.cpp
+++ b/src/Storages/StorageReplicatedMergeTree.cpp
@ -585,42 +585,24 @@ bool StorageReplicatedMergeTree::createTableIfNotExists(const StorageMetadataPtr
            /// This is Ok because another replica is definitely going to drop the table.

            LOG_WARNING(log, "Removing leftovers from table {} (this might take several minutes)", zookeeper_path);
+            String drop_lock_path = zookeeper_path + "/dropped/lock";
+            Coordination::Error code = zookeeper->tryCreate(drop_lock_path, "", zkutil::CreateMode::Ephemeral);

-            Strings children;
-            Coordination::Error code = zookeeper->tryGetChildren(zookeeper_path, children);
-            if (code == Coordination::Error::ZNONODE)
+            if (code == Coordination::Error::ZNONODE || code == Coordination::Error::ZNODEEXISTS)
            {
-                LOG_WARNING(log, "Table {} is already finished removing by another replica right now", replica_path);
+                LOG_WARNING(log, "The leftovers from table {} were removed by another replica", zookeeper_path);
+            }
+            else if (code != Coordination::Error::ZOK)
+            {
+                throw Coordination::Exception(code, drop_lock_path);
            }
            else
            {
-                for (const auto & child : children)
-                    if (child != "dropped")
-                        zookeeper->tryRemoveRecursive(zookeeper_path + "/" + child);
-
-                Coordination::Requests ops;
-                Coordination::Responses responses;
-                ops.emplace_back(zkutil::makeRemoveRequest(zookeeper_path + "/dropped", -1));
-                ops.emplace_back(zkutil::makeRemoveRequest(zookeeper_path, -1));
-                code = zookeeper->tryMulti(ops, responses);
-
-                if (code == Coordination::Error::ZNONODE)
+                auto metadata_drop_lock = zkutil::EphemeralNodeHolder::existing(drop_lock_path, *zookeeper);
+                if (!removeTableNodesFromZooKeeper(zookeeper, zookeeper_path, metadata_drop_lock, log))
                {
-                    LOG_WARNING(log, "Table {} is already finished removing by another replica right now", replica_path);
-                }
-                else if (code == Coordination::Error::ZNOTEMPTY)
-                {
-                    throw Exception(fmt::format(
-                        "The old table was not completely removed from ZooKeeper, {} still exists and may contain some garbage. But it should never happen according to the logic of operations (it's a bug).", zookeeper_path), ErrorCodes::LOGICAL_ERROR);
-                }
-                else if (code != Coordination::Error::ZOK)
-                {
-                    /// It is still possible that ZooKeeper session is expired or server is killed in the middle of the delete operation.
-                    zkutil::KeeperMultiException::check(code, ops, responses);
-                }
-                else
-                {
-                    LOG_WARNING(log, "The leftovers from table {} was successfully removed from ZooKeeper", zookeeper_path);
+                    /// Someone is recursively removing table right now, we cannot create new table until old one is removed
+                    continue;
                }
            }
        }
@ -633,10 +615,6 @@ bool StorageReplicatedMergeTree::createTableIfNotExists(const StorageMetadataPtr
        Coordination::Requests ops;
        ops.emplace_back(zkutil::makeCreateRequest(zookeeper_path, "", zkutil::CreateMode::Persistent));

-        /// Check that the table is not being dropped right now.
-        ops.emplace_back(zkutil::makeCreateRequest(zookeeper_path + "/dropped", "", zkutil::CreateMode::Persistent));
-        ops.emplace_back(zkutil::makeRemoveRequest(zookeeper_path + "/dropped", -1));
-
        ops.emplace_back(zkutil::makeCreateRequest(zookeeper_path + "/metadata", metadata_str,
            zkutil::CreateMode::Persistent));
        ops.emplace_back(zkutil::makeCreateRequest(zookeeper_path + "/columns", metadata_snapshot->getColumns().toString(),
@ -824,10 +802,18 @@ void StorageReplicatedMergeTree::dropReplica(zkutil::ZooKeeperPtr zookeeper, con
      * because table creation is executed in single transaction that will conflict with remaining nodes.
      */

+    /// Node /dropped works like a lock that protects from concurrent removal of old table and creation of new table.
+    /// But recursive removal may fail in the middle of operation leaving some garbage in zookeeper_path, so
+    /// we remove it on table creation if there is /dropped node. Creating thread may remove /dropped node created by
+    /// removing thread, and it causes race condition if removing thread is not finished yet.
+    /// To avoid this we also create ephemeral child before starting recursive removal.
+    /// (The existence of child node does not allow to remove parent node).
    Coordination::Requests ops;
    Coordination::Responses responses;
+    String drop_lock_path = zookeeper_path + "/dropped/lock";
    ops.emplace_back(zkutil::makeRemoveRequest(zookeeper_path + "/replicas", -1));
    ops.emplace_back(zkutil::makeCreateRequest(zookeeper_path + "/dropped", "", zkutil::CreateMode::Persistent));
+    ops.emplace_back(zkutil::makeCreateRequest(drop_lock_path, "", zkutil::CreateMode::Ephemeral));
    Coordination::Error code = zookeeper->tryMulti(ops, responses);

    if (code == Coordination::Error::ZNONODE || code == Coordination::Error::ZNODEEXISTS)
@ -844,48 +830,57 @@ void StorageReplicatedMergeTree::dropReplica(zkutil::ZooKeeperPtr zookeeper, con
    }
    else
    {
+        auto metadata_drop_lock = zkutil::EphemeralNodeHolder::existing(drop_lock_path, *zookeeper);
        LOG_INFO(logger, "Removing table {} (this might take several minutes)", zookeeper_path);
-
-        Strings children;
-        code = zookeeper->tryGetChildren(zookeeper_path, children);
-        if (code == Coordination::Error::ZNONODE)
-        {
-            LOG_WARNING(logger, "Table {} is already finished removing by another replica right now", remote_replica_path);
-        }
-        else
-        {
-            for (const auto & child : children)
-                if (child != "dropped")
-                    zookeeper->tryRemoveRecursive(zookeeper_path + "/" + child);
-
-            ops.clear();
-            responses.clear();
-            ops.emplace_back(zkutil::makeRemoveRequest(zookeeper_path + "/dropped", -1));
-            ops.emplace_back(zkutil::makeRemoveRequest(zookeeper_path, -1));
-            code = zookeeper->tryMulti(ops, responses);
-
-            if (code == Coordination::Error::ZNONODE)
-            {
-                LOG_WARNING(logger, "Table {} is already finished removing by another replica right now", remote_replica_path);
-            }
-            else if (code == Coordination::Error::ZNOTEMPTY)
-            {
-                LOG_ERROR(logger, "Table was not completely removed from ZooKeeper, {} still exists and may contain some garbage.",
-                          zookeeper_path);
-            }
-            else if (code != Coordination::Error::ZOK)
-            {
-                /// It is still possible that ZooKeeper session is expired or server is killed in the middle of the delete operation.
-                zkutil::KeeperMultiException::check(code, ops, responses);
-            }
-            else
-            {
-                LOG_INFO(logger, "Table {} was successfully removed from ZooKeeper", zookeeper_path);
-            }
-        }
+        removeTableNodesFromZooKeeper(zookeeper, zookeeper_path, metadata_drop_lock, logger);
    }
 }

+bool StorageReplicatedMergeTree::removeTableNodesFromZooKeeper(zkutil::ZooKeeperPtr zookeeper,
+        const String & zookeeper_path, const zkutil::EphemeralNodeHolder::Ptr & metadata_drop_lock, Poco::Logger * logger)
+{
+    bool completely_removed = false;
+    Strings children;
+    Coordination::Error code = zookeeper->tryGetChildren(zookeeper_path, children);
+    if (code == Coordination::Error::ZNONODE)
+        throw Exception(ErrorCodes::LOGICAL_ERROR, "There is a race condition between creation and removal of replicated table. It's a bug");
+
+
+    for (const auto & child : children)
+        if (child != "dropped")
+            zookeeper->tryRemoveRecursive(zookeeper_path + "/" + child);
+
+    Coordination::Requests ops;
+    Coordination::Responses responses;
+    ops.emplace_back(zkutil::makeRemoveRequest(metadata_drop_lock->getPath(), -1));
+    ops.emplace_back(zkutil::makeRemoveRequest(zookeeper_path + "/dropped", -1));
+    ops.emplace_back(zkutil::makeRemoveRequest(zookeeper_path, -1));
+    code = zookeeper->tryMulti(ops, responses);
+
+    if (code == Coordination::Error::ZNONODE)
+    {
+        throw Exception(ErrorCodes::LOGICAL_ERROR, "There is a race condition between creation and removal of replicated table. It's a bug");
+    }
+    else if (code == Coordination::Error::ZNOTEMPTY)
+    {
+        LOG_ERROR(logger, "Table was not completely removed from ZooKeeper, {} still exists and may contain some garbage,"
+                          "but someone is removing it right now.", zookeeper_path);
+    }
+    else if (code != Coordination::Error::ZOK)
+    {
+        /// It is still possible that ZooKeeper session is expired or server is killed in the middle of the delete operation.
+        zkutil::KeeperMultiException::check(code, ops, responses);
+    }
+    else
+    {
+        metadata_drop_lock->setAlreadyRemoved();
+        completely_removed = true;
+        LOG_INFO(logger, "Table {} was successfully removed from ZooKeeper", zookeeper_path);
+    }
+
+    return completely_removed;
+}
+

 /** Verify that list of columns and table storage_settings_ptr match those specified in ZK (/metadata).
  * If not, throw an exception.
--- a/src/Storages/StorageReplicatedMergeTree.h
+++ b/src/Storages/StorageReplicatedMergeTree.h
@ -208,6 +208,10 @@ public:
     */
    static void dropReplica(zkutil::ZooKeeperPtr zookeeper, const String & zookeeper_path, const String & replica, Poco::Logger * logger);

+    /// Removes table from ZooKeeper after the last replica was dropped
+    static bool removeTableNodesFromZooKeeper(zkutil::ZooKeeperPtr zookeeper, const String & zookeeper_path,
+                                              const zkutil::EphemeralNodeHolder::Ptr & metadata_drop_lock, Poco::Logger * logger);
+
    /// Get job to execute in background pool (merge, mutate, drop range and so on)
    std::optional<JobAndPool> getDataProcessingJob() override;

--- a/src/Storages/System/IStorageSystemOneBlock.h
+++ b/src/Storages/System/IStorageSystemOneBlock.h
@ -12,7 +12,16 @@ namespace DB
 class Context;


-/** Base class for system tables whose all columns have String type.
+/** IStorageSystemOneBlock is base class for system tables whose all columns can be synchronously fetched.
+  *
+  * Client class need to provide static method static NamesAndTypesList getNamesAndTypes() that will return list of column names and
+  * their types. IStorageSystemOneBlock during read will create result columns in same order as result of getNamesAndTypes
+  * and pass it with fillData method.
+  *
+  * Client also must override fillData and fill result columns.
+  *
+  * If subclass want to support virtual columns, it should override getVirtuals method of IStorage interface.
+  * IStorageSystemOneBlock will add virtuals columns at the end of result columns of fillData method.
  */
 template <typename Self>
 class IStorageSystemOneBlock : public IStorage
@ -41,9 +50,10 @@ public:
        size_t /*max_block_size*/,
        unsigned /*num_streams*/) override
    {
-        metadata_snapshot->check(column_names, getVirtuals(), getStorageID());
+        auto virtuals_names_and_types = getVirtuals();
+        metadata_snapshot->check(column_names, virtuals_names_and_types, getStorageID());

-        Block sample_block = metadata_snapshot->getSampleBlock();
+        Block sample_block = metadata_snapshot->getSampleBlockWithVirtuals(virtuals_names_and_types);
        MutableColumns res_columns = sample_block.cloneEmptyColumns();
        fillData(res_columns, context, query_info);

--- a/src/Storages/System/StorageSystemDictionaries.cpp
+++ b/src/Storages/System/StorageSystemDictionaries.cpp
@ -50,6 +50,13 @@ NamesAndTypesList StorageSystemDictionaries::getNamesAndTypes()
    };
 }

+NamesAndTypesList StorageSystemDictionaries::getVirtuals() const
+{
+    return {
+        {"key", std::make_shared<DataTypeString>()}
+    };
+}
+
 void StorageSystemDictionaries::fillData(MutableColumns & res_columns, ContextPtr context, const SelectQueryInfo & /*query_info*/) const
 {
    const auto access = context->getAccess();
@ -128,6 +135,9 @@ void StorageSystemDictionaries::fillData(MutableColumns & res_columns, ContextPt
        else
            res_columns[i++]->insertDefault();

+        /// Start fill virtual columns
+
+        res_columns[i++]->insert(dictionary_structure.getKeyDescription());
    }
 }

--- a/src/Storages/System/StorageSystemDictionaries.h
+++ b/src/Storages/System/StorageSystemDictionaries.h
@ -18,6 +18,8 @@ public:

    static NamesAndTypesList getNamesAndTypes();

+    NamesAndTypesList getVirtuals() const override;
+
 protected:
    using IStorageSystemOneBlock::IStorageSystemOneBlock;

--- a/tests/integration/test_storage_kafka/test.py
+++ b/tests/integration/test_storage_kafka/test.py
--- a/tests/queries/0_stateless/01305_replica_create_drop_zookeeper.sh
+++ b/tests/queries/0_stateless/01305_replica_create_drop_zookeeper.sh
@ -11,11 +11,10 @@ function thread()
    while true; do
        $CLICKHOUSE_CLIENT -n -q "DROP TABLE IF EXISTS test_table_$1 SYNC;
            CREATE TABLE test_table_$1 (a UInt8) ENGINE = ReplicatedMergeTree('/clickhouse/tables/$CLICKHOUSE_TEST_ZOOKEEPER_PREFIX/alter_table', 'r_$1') ORDER BY tuple();" 2>&1 |
-                grep -vP '(^$)|(^Received exception from server)|(^\d+\. )|because the last replica of the table was dropped right now|is already started to be removing by another replica right now|is already finished removing by another replica right now|Removing leftovers from table|Another replica was suddenly created|was successfully removed from ZooKeeper|was created by another server at the same moment|was suddenly removed|some other replicas were created at the same time'
+                grep -vP '(^$)|(^Received exception from server)|(^\d+\. )|because the last replica of the table was dropped right now|is already started to be removing by another replica right now| were removed by another replica|Removing leftovers from table|Another replica was suddenly created|was created by another server at the same moment|was suddenly removed|some other replicas were created at the same time'
    done
 }

-
 # https://stackoverflow.com/questions/9954794/execute-a-shell-function-with-timeout
 export -f thread;

--- a/tests/queries/0_stateless/01700_deltasum.reference
+++ b/tests/queries/0_stateless/01700_deltasum.reference
@ -7,3 +7,4 @@
 2
 2.25
 6.5
+7
--- a/tests/queries/0_stateless/01700_deltasum.sql
+++ b/tests/queries/0_stateless/01700_deltasum.sql
@ -7,3 +7,4 @@ select deltaSumMerge(rows) from (select deltaSumState(arrayJoin([0, 1])) as rows
 select deltaSumMerge(rows) from (select deltaSumState(arrayJoin([4, 5])) as rows union all select deltaSumState(arrayJoin([0, 1])) as rows);
 select deltaSum(arrayJoin([2.25, 3, 4.5]));
 select deltaSumMerge(rows) from (select deltaSumState(arrayJoin([0.1, 0.3, 0.5])) as rows union all select deltaSumState(arrayJoin([4.1, 5.1, 6.6])) as rows);
+select deltaSumMerge(rows) from (select deltaSumState(arrayJoin([3, 5])) as rows union all select deltaSumState(arrayJoin([1, 2])) as rows union all select deltaSumState(arrayJoin([4, 6])) as rows);
--- a/tests/queries/0_stateless/01739_index_hint.reference
+++ b/tests/queries/0_stateless/01739_index_hint.reference
@ -0,0 +1,35 @@
+-- { echo }
+
+drop table if exists tbl;
+create table tbl (p Int64, t Int64, f Float64) Engine=MergeTree partition by p order by t settings index_granularity=1;
+insert into tbl select number / 4, number, 0 from numbers(16);
+select * from tbl WHERE indexHint(t = 1) order by t;
+0	0	0
+0	1	0
+select * from tbl WHERE indexHint(t in (select toInt64(number) + 2 from numbers(3))) order by t;
+0	1	0
+0	2	0
+0	3	0
+1	4	0
+select * from tbl WHERE indexHint(p = 2) order by t;
+2	8	0
+2	9	0
+2	10	0
+2	11	0
+select * from tbl WHERE indexHint(p in (select toInt64(number) - 2 from numbers(3))) order by t;
+0	0	0
+0	1	0
+0	2	0
+0	3	0
+drop table tbl;
+drop table if exists XXXX;
+create table XXXX (t Int64, f Float64) Engine=MergeTree order by t settings index_granularity=128;
+insert into XXXX select number*60, 0 from numbers(100000);
+SELECT count() FROM XXXX WHERE indexHint(t = 42);
+128
+drop table if exists XXXX;
+create table XXXX (t Int64, f Float64) Engine=MergeTree order by t settings index_granularity=8192;
+insert into XXXX select number*60, 0 from numbers(100000);
+SELECT count() FROM XXXX WHERE indexHint(t = toDateTime(0));
+100000
+drop table XXXX;
--- a/tests/queries/0_stateless/01739_index_hint.sql
+++ b/tests/queries/0_stateless/01739_index_hint.sql
@ -0,0 +1,35 @@
+-- { echo }
+
+drop table if exists tbl;
+
+create table tbl (p Int64, t Int64, f Float64) Engine=MergeTree partition by p order by t settings index_granularity=1;
+
+insert into tbl select number / 4, number, 0 from numbers(16);
+
+select * from tbl WHERE indexHint(t = 1) order by t;
+
+select * from tbl WHERE indexHint(t in (select toInt64(number) + 2 from numbers(3))) order by t;
+
+select * from tbl WHERE indexHint(p = 2) order by t;
+
+select * from tbl WHERE indexHint(p in (select toInt64(number) - 2 from numbers(3))) order by t;
+
+drop table tbl;
+
+drop table if exists XXXX;
+
+create table XXXX (t Int64, f Float64) Engine=MergeTree order by t settings index_granularity=128;
+
+insert into XXXX select number*60, 0 from numbers(100000);
+
+SELECT count() FROM XXXX WHERE indexHint(t = 42);
+
+drop table if exists XXXX;
+
+create table XXXX (t Int64, f Float64) Engine=MergeTree order by t settings index_granularity=8192;
+
+insert into XXXX select number*60, 0 from numbers(100000);
+
+SELECT count() FROM XXXX WHERE indexHint(t = toDateTime(0));
+
+drop table XXXX;
--- a/tests/queries/0_stateless/01813_distributed_scalar_subqueries_alias.reference
+++ b/tests/queries/0_stateless/01813_distributed_scalar_subqueries_alias.reference
@ -0,0 +1,4 @@
+0
+1
+0
+1
--- a/tests/queries/0_stateless/01813_distributed_scalar_subqueries_alias.sql
+++ b/tests/queries/0_stateless/01813_distributed_scalar_subqueries_alias.sql
@ -0,0 +1,18 @@
+DROP TABLE IF EXISTS data;
+CREATE TABLE data (a Int64, b Int64) ENGINE = TinyLog();
+
+DROP TABLE IF EXISTS data_distributed;
+CREATE TABLE data_distributed (a Int64, b Int64) ENGINE = Distributed(test_shard_localhost, currentDatabase(), 'data');
+
+INSERT INTO data VALUES (0, 0);
+
+SET prefer_localhost_replica = 1;
+SELECT a / (SELECT sum(number) FROM numbers(10)) FROM data_distributed;
+SELECT a < (SELECT 1) FROM data_distributed;
+
+SET prefer_localhost_replica = 0;
+SELECT a / (SELECT sum(number) FROM numbers(10)) FROM data_distributed;
+SELECT a < (SELECT 1) FROM data_distributed;
+
+DROP TABLE data_distributed;
+DROP TABLE data;
--- a/tests/queries/0_stateless/01822_async_read_from_socket_crash.reference
+++ b/tests/queries/0_stateless/01822_async_read_from_socket_crash.reference
--- a/tests/queries/0_stateless/01822_async_read_from_socket_crash.sh
+++ b/tests/queries/0_stateless/01822_async_read_from_socket_crash.sh
@ -0,0 +1,9 @@
+#!/usr/bin/env bash
+
+CURDIR=$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)
+# shellcheck source=../shell_config.sh
+. "$CURDIR"/../shell_config.sh
+
+
+
+for _ in {1..10}; do $CLICKHOUSE_CLIENT -q "select number from remote('127.0.0.{2,3}', numbers(20)) limit 8 settings max_block_size = 2, unknown_packet_in_send_data=4, sleep_in_send_data_ms=100, async_socket_for_remote=1 format Null" > /dev/null 2>&1 || true; done
--- a/tests/queries/0_stateless/01822_union_and_constans_error.reference
+++ b/tests/queries/0_stateless/01822_union_and_constans_error.reference
@ -0,0 +1 @@
+1
--- a/tests/queries/0_stateless/01822_union_and_constans_error.sql
+++ b/tests/queries/0_stateless/01822_union_and_constans_error.sql
@ -0,0 +1,20 @@
+drop table if exists t0;
+CREATE TABLE t0 (c0 String) ENGINE = Log();
+
+SELECT isNull(t0.c0) OR COUNT('\n?pVa')
+FROM t0
+GROUP BY t0.c0
+HAVING isNull(t0.c0)
+UNION ALL
+SELECT isNull(t0.c0) OR COUNT('\n?pVa')
+FROM t0
+GROUP BY t0.c0
+HAVING NOT isNull(t0.c0)
+UNION ALL
+SELECT isNull(t0.c0) OR COUNT('\n?pVa')
+FROM t0
+GROUP BY t0.c0
+HAVING isNull(isNull(t0.c0))
+SETTINGS aggregate_functions_null_for_empty = 1, enable_optimize_predicate_expression = 0;
+
+drop table if exists t0;
--- a/tests/queries/0_stateless/01833_test_collation_alvarotuso.reference
+++ b/tests/queries/0_stateless/01833_test_collation_alvarotuso.reference
@ -0,0 +1,6 @@
+a	a
+A	A
+b	b
+B	B
+c	c
+C	C
--- a/tests/queries/0_stateless/01833_test_collation_alvarotuso.sql
+++ b/tests/queries/0_stateless/01833_test_collation_alvarotuso.sql
@ -0,0 +1,21 @@
+DROP TABLE IF EXISTS test_collation;
+
+CREATE TABLE test_collation
+(
+    `v` String,
+    `v2` String
+)
+ENGINE = MergeTree
+ORDER BY v
+SETTINGS index_granularity = 8192;
+
+insert into test_collation values ('A', 'A');
+insert into test_collation values ('B', 'B');
+insert into test_collation values ('C', 'C');
+insert into test_collation values ('a', 'a');
+insert into test_collation values ('b', 'b');
+insert into test_collation values ('c', 'c');
+
+SELECT * FROM test_collation ORDER BY v ASC COLLATE 'en';
+
+DROP TABLE test_collation;
--- a/tests/queries/0_stateless/01834_alias_columns_laziness_filimonov.reference
+++ b/tests/queries/0_stateless/01834_alias_columns_laziness_filimonov.reference
@ -0,0 +1 @@
+Ok
--- a/tests/queries/0_stateless/01834_alias_columns_laziness_filimonov.sh
+++ b/tests/queries/0_stateless/01834_alias_columns_laziness_filimonov.sh
@ -0,0 +1,27 @@
+#!/usr/bin/env bash
+
+CUR_DIR=$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)
+# shellcheck source=../shell_config.sh
+. "$CUR_DIR"/../shell_config.sh
+
+${CLICKHOUSE_CLIENT} --multiquery --query "
+drop table if exists aliases_lazyness;
+create table aliases_lazyness (x UInt32, y ALIAS sleepEachRow(0.1)) Engine=MergeTree ORDER BY x;
+insert into aliases_lazyness(x) select * from numbers(40);
+"
+
+# In very old ClickHouse versions alias column was calculated for every row.
+# If it works this way, the query will take at least 0.1 * 40 = 4 seconds.
+# If the issue does not exist, the query should take slightly more than 0.1 seconds.
+# The exact time is not guaranteed, so we check in a loop that at least once 
+# the query will process in less than one second, that proves that the behaviour is not like it was long time ago.
+
+while true
+do
+    timeout 1 ${CLICKHOUSE_CLIENT} --query "SELECT x, y FROM aliases_lazyness WHERE x = 1 FORMAT Null" && break
+done
+
+${CLICKHOUSE_CLIENT} --multiquery --query "
+drop table aliases_lazyness;
+SELECT 'Ok';
+"
--- a/tests/queries/0_stateless/01835_alias_to_primary_key_cyfdecyf.reference
+++ b/tests/queries/0_stateless/01835_alias_to_primary_key_cyfdecyf.reference
@ -0,0 +1,2 @@
+2017-12-15	1	1
+2017-12-15	1	1
--- a/tests/queries/0_stateless/01835_alias_to_primary_key_cyfdecyf.sql
+++ b/tests/queries/0_stateless/01835_alias_to_primary_key_cyfdecyf.sql
@ -0,0 +1,21 @@
+DROP TABLE IF EXISTS db;
+
+CREATE TABLE tb
+(
+    date Date,
+    `index` Int32,
+    value Int32,
+    idx Int32 ALIAS `index`
+)
+ENGINE = MergeTree
+PARTITION BY date
+ORDER BY (date, `index`);
+
+insert into tb values ('2017-12-15', 1, 1);
+
+SET force_primary_key = 1;
+
+select * from tb where `index` >= 0 AND `index` <= 2;
+select * from tb where idx >= 0 AND idx <= 2;
+
+DROP TABLE tb;
--- a/tests/queries/0_stateless/01836_date_time_keep_default_timezone_on_operations_den_crane.reference
+++ b/tests/queries/0_stateless/01836_date_time_keep_default_timezone_on_operations_den_crane.reference
@ -0,0 +1,6 @@
+DateTime
+DateTime
+DateTime(\'UTC\')
+DateTime64(3)
+DateTime64(3)
+DateTime64(3, \'UTC\')
--- a/tests/queries/0_stateless/01836_date_time_keep_default_timezone_on_operations_den_crane.sql
+++ b/tests/queries/0_stateless/01836_date_time_keep_default_timezone_on_operations_den_crane.sql
@ -0,0 +1,26 @@
+SELECT toTypeName(now());
+SELECT toTypeName(now() - 1);
+SELECT toTypeName(now('UTC') - 1);
+
+SELECT toTypeName(now64(3));
+SELECT toTypeName(now64(3) - 1);
+SELECT toTypeName(toTimeZone(now64(3), 'UTC') - 1);
+
+DROP TABLE IF EXISTS tt_null;
+DROP TABLE IF EXISTS tt;
+DROP TABLE IF EXISTS tt_mv;
+
+create table tt_null(p String) engine = Null;
+
+create table tt(p String,tmin AggregateFunction(min, DateTime)) 
+engine = AggregatingMergeTree  order by p;
+
+create materialized view tt_mv to tt as 
+select p, minState(now() - interval 30 minute) as tmin
+from tt_null group by p;
+
+insert into tt_null values('x');
+
+DROP TABLE tt_null;
+DROP TABLE tt;
+DROP TABLE tt_mv;
--- a/tests/queries/0_stateless/01837_cast_to_array_from_empty_array.reference
+++ b/tests/queries/0_stateless/01837_cast_to_array_from_empty_array.reference
@ -0,0 +1,2 @@
+[]
+[]
--- a/Show More
+++ b/Show More