Merge branch 'master' into add-separate-access-for-use-named-collections

docker/test/integration/runner/Dockerfile

@@ -47,11 +47,13 @@ ENV TZ=Etc/UTC
 RUN ln -snf /usr/share/zoneinfo/$TZ /etc/localtime && echo $TZ > /etc/timezone
 
 ENV DOCKER_CHANNEL stable
+# Unpin the docker version after the release 24.0.3 is released
+# https://github.com/moby/moby/issues/45770#issuecomment-1618255130
 RUN curl -fsSL https://download.docker.com/linux/ubuntu/gpg | apt-key add - \
     && add-apt-repository "deb https://download.docker.com/linux/ubuntu $(lsb_release -c -s) ${DOCKER_CHANNEL}" \
     && apt-get update \
     && env DEBIAN_FRONTEND=noninteractive apt-get install --yes \
-        docker-ce \
+        docker-ce='5:23.*' \
     && rm -rf \
         /var/lib/apt/lists/* \
         /var/cache/debconf \

docker/test/upgrade/run.sh

@@ -76,7 +76,8 @@ sudo mv /etc/clickhouse-server/config.d/keeper_port.xml.tmp /etc/clickhouse-serv
 # But we still need default disk because some tables loaded only into it
 sudo cat /etc/clickhouse-server/config.d/s3_storage_policy_by_default.xml \
   | sed "s|<main><disk>s3</disk></main>|<main><disk>s3</disk></main><default><disk>default</disk></default>|" \
-  > /etc/clickhouse-server/config.d/s3_storage_policy_by_default.xml.tmp    mv /etc/clickhouse-server/config.d/s3_storage_policy_by_default.xml.tmp /etc/clickhouse-server/config.d/s3_storage_policy_by_default.xml
+  > /etc/clickhouse-server/config.d/s3_storage_policy_by_default.xml.tmp
+mv /etc/clickhouse-server/config.d/s3_storage_policy_by_default.xml.tmp /etc/clickhouse-server/config.d/s3_storage_policy_by_default.xml
 sudo chown clickhouse /etc/clickhouse-server/config.d/s3_storage_policy_by_default.xml
 sudo chgrp clickhouse /etc/clickhouse-server/config.d/s3_storage_policy_by_default.xml
 

docs/en/engines/table-engines/integrations/odbc.md

@@ -54,7 +54,7 @@ $ sudo mysql
 
 ``` sql
 mysql> CREATE USER 'clickhouse'@'localhost' IDENTIFIED BY 'clickhouse';
-mysql> GRANT ALL PRIVILEGES ON *.* TO 'clickhouse'@'clickhouse' WITH GRANT OPTION;
+mysql> GRANT ALL PRIVILEGES ON *.* TO 'clickhouse'@'localhost' WITH GRANT OPTION;
 ```
 
 Then configure the connection in `/etc/odbc.ini`.
@@ -66,7 +66,7 @@ DRIVER = /usr/local/lib/libmyodbc5w.so
 SERVER = 127.0.0.1
 PORT = 3306
 DATABASE = test
-USERNAME = clickhouse
+USER = clickhouse
 PASSWORD = clickhouse
 ```
 
@@ -83,6 +83,9 @@ $ isql -v mysqlconn
 Table in MySQL:
 
 ``` text
+mysql> CREATE DATABASE test;
+Query OK, 1 row affected (0,01 sec)
+
 mysql> CREATE TABLE `test`.`test` (
     ->   `int_id` INT NOT NULL AUTO_INCREMENT,
     ->   `int_nullable` INT NULL DEFAULT NULL,
@@ -91,10 +94,10 @@ mysql> CREATE TABLE `test`.`test` (
     ->   PRIMARY KEY (`int_id`));
 Query OK, 0 rows affected (0,09 sec)
 
-mysql> insert into test (`int_id`, `float`) VALUES (1,2);
+mysql> insert into test.test (`int_id`, `float`) VALUES (1,2);
 Query OK, 1 row affected (0,00 sec)
 
-mysql> select * from test;
+mysql> select * from test.test;
 +------+----------+-----+----------+
 | int_id | int_nullable | float | float_nullable |
 +------+----------+-----+----------+

docs/zh/sql-reference/functions/functions-for-nulls.md

@@ -192,7 +192,7 @@ SELECT coalesce(mail, phone, CAST(icq,'Nullable(String)')) FROM aBook
 **返回值**
 
 -   如果`x`不为`NULL`，返回非`Nullable`类型的原始值。
--   如果`x`为`NULL`，返回对应非`Nullable`类型的默认值。
+-   如果`x`为`NULL`，则返回任意值。
 
 **示例**
 

programs/local/LocalServer.cpp

@@ -8,7 +8,9 @@
 #include <Poco/Logger.h>
 #include <Poco/NullChannel.h>
 #include <Poco/SimpleFileChannel.h>
+#include <Databases/DatabaseFilesystem.h>
 #include <Databases/DatabaseMemory.h>
+#include <Databases/DatabasesOverlay.h>
 #include <Storages/System/attachSystemTables.h>
 #include <Storages/System/attachInformationSchemaTables.h>
 #include <Interpreters/DatabaseCatalog.h>
@@ -50,6 +52,8 @@
 #include <base/argsToConfig.h>
 #include <filesystem>
 
+#include "config.h"
+
 #if defined(FUZZING_MODE)
     #include <Functions/getFuzzerData.h>
 #endif
@@ -170,6 +174,13 @@ static DatabasePtr createMemoryDatabaseIfNotExists(ContextPtr context, const Str
     return system_database;
 }
 
+static DatabasePtr createClickHouseLocalDatabaseOverlay(const String & name_, ContextPtr context_)
+{
+    auto databaseCombiner = std::make_shared<DatabasesOverlay>(name_, context_);
+    databaseCombiner->registerNextDatabase(std::make_shared<DatabaseFilesystem>(name_, "", context_));
+    databaseCombiner->registerNextDatabase(std::make_shared<DatabaseMemory>(name_, context_));
+    return databaseCombiner;
+}
 
 /// If path is specified and not empty, will try to setup server environment and load existing metadata
 void LocalServer::tryInitPath()
@@ -669,7 +680,7 @@ void LocalServer::processConfig()
       *  if such tables will not be dropped, clickhouse-server will not be able to load them due to security reasons.
       */
     std::string default_database = config().getString("default_database", "_local");
-    DatabaseCatalog::instance().attachDatabase(default_database, std::make_shared<DatabaseMemory>(default_database, global_context));
+    DatabaseCatalog::instance().attachDatabase(default_database, createClickHouseLocalDatabaseOverlay(default_database, global_context));
     global_context->setCurrentDatabase(default_database);
     applyCmdOptions(global_context);
 

programs/server/dashboard.html

@@ -12,7 +12,8 @@
             --chart-background: white;
             --shadow-color: rgba(0, 0, 0, 0.25);
             --input-shadow-color: rgba(0, 255, 0, 1);
-            --error-color: white;
+            --error-color: red;
+            --auth-error-color: white;
             --legend-background: rgba(255, 255, 255, 0.75);
             --title-color: #666;
             --text-color: black;
@@ -258,7 +259,7 @@
             width: 60%;
             padding: .5rem;
 
-            color: var(--error-color);
+            color: var(--auth-error-color);
 
             display: flex;
             flex-flow: row nowrap;
@@ -906,9 +907,9 @@ async function draw(idx, chart, url_params, query) {
 
     if (error) {
         const errorMatch = errorMessages.find(({ regex }) => error.match(regex))
-        if (errorMatch) {
         const match = error.match(errorMatch.regex)
         const message = errorMatch.messageFunc(match)
+        if (message) {
             const authError = new Error(message)
             throw authError
         }
@@ -1019,13 +1020,15 @@ async function drawAll() {
             firstLoad = false;
         } else {
             enableReloadButton();
+            enableRunButton();
         }
-        if (!results.includes(false)) {
+        if (results.includes(true)) {
             const element = document.querySelector('.inputs');
             element.classList.remove('unconnected');
             const add = document.querySelector('#add');
             add.style.display = 'block';
-        } else {
+        } 
+        else {
             const charts = document.querySelector('#charts')
             charts.style.height = '0px';
         }
@@ -1050,6 +1053,13 @@ function disableReloadButton() {
     reloadButton.classList.add('disabled')
 }
 
+function disableRunButton() {
+    const runButton = document.getElementById('run')
+    runButton.value = 'Reloading...'
+    runButton.disabled = true
+    runButton.classList.add('disabled')
+}
+
 function enableReloadButton() {
     const reloadButton = document.getElementById('reload')
     reloadButton.value = 'Reload'
@@ -1057,11 +1067,19 @@ function enableReloadButton() {
     reloadButton.classList.remove('disabled')
 }
 
+function enableRunButton() {
+    const runButton = document.getElementById('run')
+    runButton.value = 'Ok'
+    runButton.disabled = false
+    runButton.classList.remove('disabled')
+}
+
 function reloadAll() {
     updateParams();
     drawAll();
     saveState();
-    disableReloadButton()
+    disableReloadButton();
+    disableRunButton();
 }
 
 document.getElementById('params').onsubmit = function(event) {

src/Client/ClientBase.cpp

@@ -2297,7 +2297,9 @@ void ClientBase::runInteractive()
         catch (const ErrnoException & e)
         {
             if (e.getErrno() != EEXIST)
-                throw;
+            {
+                std::cerr << getCurrentExceptionMessage(false) << '\n';
+            }
         }
     }
 

src/Client/ConnectionParameters.cpp

@@ -60,7 +60,15 @@ ConnectionParameters::ConnectionParameters(const Poco::Util::AbstractConfigurati
     quota_key = config.getString("quota_key", "");
 
     /// By default compression is disabled if address looks like localhost.
-    compression = config.getBool("compression", !isLocalAddress(DNSResolver::instance().resolveHost(host)))
+
+    /// Avoid DNS request if the host is "localhost".
+    /// If ClickHouse is run under QEMU-user with a binary for a different architecture,
+    /// and there are all listed startup dependency shared libraries available, but not the runtime dependencies of glibc,
+    /// the glibc cannot open "plugins" for DNS resolving, and the DNS resolution does not work.
+    /// At the same time, I want clickhouse-local to always work, regardless.
+    /// TODO: get rid of glibc, or replace getaddrinfo to c-ares.
+
+    compression = config.getBool("compression", host != "localhost" && !isLocalAddress(DNSResolver::instance().resolveHost(host)))
                   ? Protocol::Compression::Enable : Protocol::Compression::Disable;
 
     timeouts = ConnectionTimeouts(

src/Client/Suggest.cpp

@@ -101,9 +101,8 @@ static String getLoadSuggestionQuery(Int32 suggestion_limit, bool basic_suggesti
         add_column("name", "columns", true, suggestion_limit);
     }
 
-    /// FIXME: Forbid this query using new analyzer because of bug https://github.com/ClickHouse/ClickHouse/issues/50669
-    /// We should remove this restriction after resolving this bug.
-    query = "SELECT DISTINCT arrayJoin(extractAll(name, '[\\\\w_]{2,}')) AS res FROM (" + query + ") WHERE notEmpty(res) SETTINGS allow_experimental_analyzer=0";
+    /// FIXME: This query does not work with the new analyzer because of bug https://github.com/ClickHouse/ClickHouse/issues/50669
+    query = "SELECT DISTINCT arrayJoin(extractAll(name, '[\\\\w_]{2,}')) AS res FROM (" + query + ") WHERE notEmpty(res)";
     return query;
 }
 

src/Common/OptimizedRegularExpression.cpp

@@ -540,7 +540,7 @@ bool OptimizedRegularExpressionImpl<thread_safe>::match(const char * subject, si
             }
         }
 
-        return re2->Match(StringPieceType(subject, subject_size), 0, subject_size, RegexType::UNANCHORED, nullptr, 0);
+        return re2->Match({subject, subject_size}, 0, subject_size, RegexType::UNANCHORED, nullptr, 0);
     }
 }
 
@@ -585,9 +585,9 @@ bool OptimizedRegularExpressionImpl<thread_safe>::match(const char * subject, si
                 return false;
         }
 
-        StringPieceType piece;
+        std::string_view piece;
 
-        if (!RegexType::PartialMatch(StringPieceType(subject, subject_size), *re2, &piece))
+        if (!RegexType::PartialMatch({subject, subject_size}, *re2, &piece))
             return false;
         else
         {
@@ -652,10 +652,10 @@ unsigned OptimizedRegularExpressionImpl<thread_safe>::match(const char * subject
                 return 0;
         }
 
-        DB::PODArrayWithStackMemory<StringPieceType, 128> pieces(limit);
+        DB::PODArrayWithStackMemory<std::string_view, 128> pieces(limit);
 
         if (!re2->Match(
-            StringPieceType(subject, subject_size),
+            {subject, subject_size},
             0,
             subject_size,
             RegexType::UNANCHORED,

src/Common/OptimizedRegularExpression.h

@@ -52,7 +52,6 @@ public:
     using MatchVec = std::vector<Match>;
 
     using RegexType = std::conditional_t<thread_safe, re2::RE2, re2_st::RE2>;
-    using StringPieceType = std::conditional_t<thread_safe, re2::StringPiece, re2_st::StringPiece>;
 
     OptimizedRegularExpressionImpl(const std::string & regexp_, int options = 0); /// NOLINT
     /// StringSearcher store pointers to required_substring, it must be updated on move.

src/Common/SensitiveDataMasker.cpp

@@ -5,7 +5,6 @@
 #include <atomic>
 
 #include <re2/re2.h>
-#include <re2/stringpiece.h>
 
 #include <Poco/Util/AbstractConfiguration.h>
 
@@ -44,7 +43,7 @@ private:
     const std::string regexp_string;
 
     const RE2 regexp;
-    const re2::StringPiece replacement;
+    const std::string_view replacement;
 
 #ifndef NDEBUG
     mutable std::atomic<std::uint64_t> matches_count = 0;

src/Common/checkStackSize.cpp

@@ -27,7 +27,7 @@ static thread_local size_t max_stack_size = 0;
  * @param out_address - if not nullptr, here the address of the stack will be written.
  * @return stack size
  */
-size_t getStackSize(void ** out_address)
+static size_t getStackSize(void ** out_address)
 {
     using namespace DB;
 
@@ -54,7 +54,15 @@ size_t getStackSize(void ** out_address)
         throwFromErrno("Cannot pthread_attr_get_np", ErrorCodes::CANNOT_PTHREAD_ATTR);
 #   else
     if (0 != pthread_getattr_np(pthread_self(), &attr))
+    {
+        if (errno == ENOENT)
+        {
+            /// Most likely procfs is not mounted.
+            return 0;
+        }
+        else
             throwFromErrno("Cannot pthread_getattr_np", ErrorCodes::CANNOT_PTHREAD_ATTR);
+    }
 #   endif
 
     SCOPE_EXIT({ pthread_attr_destroy(&attr); });
@@ -83,6 +91,10 @@ __attribute__((__weak__)) void checkStackSize()
     if (!stack_address)
         max_stack_size = getStackSize(&stack_address);
 
+    /// The check is impossible.
+    if (!max_stack_size)
+        return;
+
     const void * frame_address = __builtin_frame_address(0);
     uintptr_t int_frame_address = reinterpret_cast<uintptr_t>(frame_address);
     uintptr_t int_stack_address = reinterpret_cast<uintptr_t>(stack_address);

src/Common/parseGlobs.cpp

@@ -3,7 +3,6 @@
 #include <IO/ReadBufferFromString.h>
 #include <IO/Operators.h>
 #include <re2/re2.h>
-#include <re2/stringpiece.h>
 #include <algorithm>
 #include <sstream>
 #include <iomanip>
@@ -33,14 +32,14 @@ std::string makeRegexpPatternFromGlobs(const std::string & initial_str_with_glob
     std::string escaped_with_globs = buf_for_escaping.str();
 
     static const re2::RE2 enum_or_range(R"({([\d]+\.\.[\d]+|[^{}*,]+,[^{}*]*[^{}*,])})");    /// regexp for {expr1,expr2,expr3} or {M..N}, where M and N - non-negative integers, expr's should be without "{", "}", "*" and ","
-    re2::StringPiece input(escaped_with_globs);
-    re2::StringPiece matched;
+    std::string_view input(escaped_with_globs);
+    std::string_view matched;
     std::ostringstream oss_for_replacing;       // STYLE_CHECK_ALLOW_STD_STRING_STREAM
     oss_for_replacing.exceptions(std::ios::failbit);
     size_t current_index = 0;
     while (RE2::FindAndConsume(&input, enum_or_range, &matched))
     {
-        std::string buffer{matched};
+        std::string buffer(matched);
         oss_for_replacing << escaped_with_globs.substr(current_index, matched.data() - escaped_with_globs.data() - current_index - 1) << '(';
 
         if (buffer.find(',') == std::string::npos)

src/Compression/CompressionCodecLZ4.cpp

@@ -42,7 +42,6 @@ private:
     UInt32 getMaxCompressedDataSize(UInt32 uncompressed_size) const override;
 
     mutable LZ4::PerformanceStatistics lz4_stat;
-    ASTPtr codec_desc;
 };
 
 

src/Databases/DatabaseFactory.cpp

@@ -3,6 +3,7 @@
 #include <filesystem>
 #include <Databases/DatabaseAtomic.h>
 #include <Databases/DatabaseDictionary.h>
+#include <Databases/DatabaseFilesystem.h>
 #include <Databases/DatabaseLazy.h>
 #include <Databases/DatabaseMemory.h>
 #include <Databases/DatabaseOrdinary.h>
@@ -47,6 +48,14 @@
 #include <Databases/SQLite/DatabaseSQLite.h>
 #endif
 
+#if USE_AWS_S3
+#include <Databases/DatabaseS3.h>
+#endif
+
+#if USE_HDFS
+#include <Databases/DatabaseHDFS.h>
+#endif
+
 namespace fs = std::filesystem;
 
 namespace DB
@@ -131,13 +140,13 @@ DatabasePtr DatabaseFactory::getImpl(const ASTCreateQuery & create, const String
 
     static const std::unordered_set<std::string_view> database_engines{"Ordinary", "Atomic", "Memory",
         "Dictionary", "Lazy", "Replicated", "MySQL", "MaterializeMySQL", "MaterializedMySQL",
-        "PostgreSQL", "MaterializedPostgreSQL", "SQLite"};
+        "PostgreSQL", "MaterializedPostgreSQL", "SQLite", "Filesystem", "S3", "HDFS"};
 
     if (!database_engines.contains(engine_name))
         throw Exception(ErrorCodes::BAD_ARGUMENTS, "Database engine name `{}` does not exist", engine_name);
 
     static const std::unordered_set<std::string_view> engines_with_arguments{"MySQL", "MaterializeMySQL", "MaterializedMySQL",
-        "Lazy", "Replicated", "PostgreSQL", "MaterializedPostgreSQL", "SQLite"};
+        "Lazy", "Replicated", "PostgreSQL", "MaterializedPostgreSQL", "SQLite", "Filesystem", "S3", "HDFS"};
 
     static const std::unordered_set<std::string_view> engines_with_table_overrides{"MaterializeMySQL", "MaterializedMySQL", "MaterializedPostgreSQL"};
     bool engine_may_have_arguments = engines_with_arguments.contains(engine_name);
@@ -432,6 +441,63 @@ DatabasePtr DatabaseFactory::getImpl(const ASTCreateQuery & create, const String
     }
 #endif
 
+    else if (engine_name == "Filesystem")
+    {
+        const ASTFunction * engine = engine_define->engine;
+
+        /// If init_path is empty, then the current path will be used
+        std::string init_path;
+
+        if (engine->arguments && !engine->arguments->children.empty())
+        {
+            if (engine->arguments->children.size() != 1)
+                throw Exception(ErrorCodes::BAD_ARGUMENTS, "Filesystem database requires at most 1 argument: filesystem_path");
+
+            const auto & arguments = engine->arguments->children;
+            init_path = safeGetLiteralValue<String>(arguments[0], engine_name);
+        }
+
+        return std::make_shared<DatabaseFilesystem>(database_name, init_path, context);
+    }
+
+#if USE_AWS_S3
+    else if (engine_name == "S3")
+    {
+        const ASTFunction * engine = engine_define->engine;
+
+        DatabaseS3::Configuration config;
+
+        if (engine->arguments && !engine->arguments->children.empty())
+        {
+            ASTs & engine_args = engine->arguments->children;
+            config = DatabaseS3::parseArguments(engine_args, context);
+        }
+
+        return std::make_shared<DatabaseS3>(database_name, config, context);
+    }
+#endif
+
+#if USE_HDFS
+    else if (engine_name == "HDFS")
+    {
+        const ASTFunction * engine = engine_define->engine;
+
+        /// If source_url is empty, then table name must contain full url
+        std::string source_url;
+
+        if (engine->arguments && !engine->arguments->children.empty())
+        {
+            if (engine->arguments->children.size() != 1)
+                throw Exception(ErrorCodes::BAD_ARGUMENTS, "HDFS database requires at most 1 argument: source_url");
+
+            const auto & arguments = engine->arguments->children;
+            source_url = safeGetLiteralValue<String>(arguments[0], engine_name);
+        }
+
+        return std::make_shared<DatabaseHDFS>(database_name, source_url, context);
+    }
+#endif
+
     throw Exception(ErrorCodes::UNKNOWN_DATABASE_ENGINE, "Unknown database engine: {}", engine_name);
 }
 

src/Databases/DatabaseFilesystem.cpp

@@ -0,0 +1,245 @@
+#include <Databases/DatabaseFilesystem.h>
+
+#include <IO/Operators.h>
+#include <IO/WriteBufferFromString.h>
+#include <Interpreters/Context.h>
+#include <Parsers/ASTCreateQuery.h>
+#include <Parsers/ASTFunction.h>
+#include <Parsers/ASTLiteral.h>
+#include <Parsers/ParserCreateQuery.h>
+#include <Parsers/parseQuery.h>
+#include <Storages/IStorage.h>
+#include <TableFunctions/TableFunctionFactory.h>
+#include <Common/filesystemHelpers.h>
+
+#include <filesystem>
+
+namespace fs = std::filesystem;
+
+namespace DB
+{
+
+namespace ErrorCodes
+{
+    extern const int LOGICAL_ERROR;
+    extern const int UNKNOWN_TABLE;
+    extern const int PATH_ACCESS_DENIED;
+    extern const int BAD_ARGUMENTS;
+    extern const int FILE_DOESNT_EXIST;
+}
+
+DatabaseFilesystem::DatabaseFilesystem(const String & name_, const String & path_, ContextPtr context_)
+    : IDatabase(name_), WithContext(context_->getGlobalContext()), path(path_), log(&Poco::Logger::get("DatabaseFileSystem(" + name_ + ")"))
+{
+    bool is_local = context_->getApplicationType() == Context::ApplicationType::LOCAL;
+    fs::path user_files_path = is_local ? "" : fs::canonical(getContext()->getUserFilesPath());
+
+    if (fs::path(path).is_relative())
+    {
+        path = user_files_path / path;
+    }
+    else if (!is_local && !pathStartsWith(fs::path(path), user_files_path))
+    {
+        throw Exception(ErrorCodes::BAD_ARGUMENTS,
+                        "Path must be inside user-files path: {}", user_files_path.string());
+    }
+
+    path = fs::absolute(path).lexically_normal();
+    if (!fs::exists(path))
+        throw Exception(ErrorCodes::BAD_ARGUMENTS, "Path does not exist: {}", path);
+}
+
+std::string DatabaseFilesystem::getTablePath(const std::string & table_name) const
+{
+    fs::path table_path = fs::path(path) / table_name;
+    return table_path.lexically_normal().string();
+}
+
+void DatabaseFilesystem::addTable(const std::string & table_name, StoragePtr table_storage) const
+{
+    std::lock_guard lock(mutex);
+    auto [_, inserted] = loaded_tables.emplace(table_name, table_storage);
+    if (!inserted)
+        throw Exception(
+            ErrorCodes::LOGICAL_ERROR,
+            "Table with name `{}` already exists in database `{}` (engine {})",
+            table_name, getDatabaseName(), getEngineName());
+}
+
+bool DatabaseFilesystem::checkTableFilePath(const std::string & table_path, ContextPtr context_, bool throw_on_error) const
+{
+    /// If run in Local mode, no need for path checking.
+    bool check_path = context_->getApplicationType() != Context::ApplicationType::LOCAL;
+    const auto & user_files_path = context_->getUserFilesPath();
+
+    /// Check access for file before checking its existence.
+    if (check_path && !fileOrSymlinkPathStartsWith(table_path, user_files_path))
+    {
+        if (throw_on_error)
+            throw Exception(ErrorCodes::PATH_ACCESS_DENIED, "File is not inside {}", user_files_path);
+        else
+            return false;
+    }
+
+    /// Check if the corresponding file exists.
+    if (!fs::exists(table_path))
+    {
+        if (throw_on_error)
+            throw Exception(ErrorCodes::FILE_DOESNT_EXIST, "File does not exist: {}", table_path);
+        else
+            return false;
+    }
+
+    if (!fs::is_regular_file(table_path))
+    {
+        if (throw_on_error)
+            throw Exception(ErrorCodes::FILE_DOESNT_EXIST,
+                            "File is directory, but expected a file: {}", table_path);
+        else
+            return false;
+    }
+
+    return true;
+}
+
+StoragePtr DatabaseFilesystem::tryGetTableFromCache(const std::string & name) const
+{
+    StoragePtr table = nullptr;
+    {
+        std::lock_guard lock(mutex);
+        auto it = loaded_tables.find(name);
+        if (it != loaded_tables.end())
+            table = it->second;
+    }
+
+    /// Invalidate cache if file no longer exists.
+    if (table && !fs::exists(getTablePath(name)))
+    {
+        std::lock_guard lock(mutex);
+        loaded_tables.erase(name);
+        return nullptr;
+    }
+
+    return table;
+}
+
+bool DatabaseFilesystem::isTableExist(const String & name, ContextPtr context_) const
+{
+    if (tryGetTableFromCache(name))
+        return true;
+
+    return checkTableFilePath(getTablePath(name), context_, /* throw_on_error */false);
+}
+
+StoragePtr DatabaseFilesystem::getTableImpl(const String & name, ContextPtr context_) const
+{
+    /// Check if table exists in loaded tables map.
+    if (auto table = tryGetTableFromCache(name))
+        return table;
+
+    auto table_path = getTablePath(name);
+    checkTableFilePath(table_path, context_, /* throw_on_error */true);
+
+    /// If the file exists, create a new table using TableFunctionFile and return it.
+    auto args = makeASTFunction("file", std::make_shared<ASTLiteral>(table_path));
+
+    auto table_function = TableFunctionFactory::instance().get(args, context_);
+    if (!table_function)
+        return nullptr;
+
+    /// TableFunctionFile throws exceptions, if table cannot be created.
+    auto table_storage = table_function->execute(args, context_, name);
+    if (table_storage)
+        addTable(name, table_storage);
+
+    return table_storage;
+}
+
+StoragePtr DatabaseFilesystem::getTable(const String & name, ContextPtr context_) const
+{
+    /// getTableImpl can throw exceptions, do not catch them to show correct error to user.
+    if (auto storage = getTableImpl(name, context_))
+        return storage;
+
+    throw Exception(ErrorCodes::UNKNOWN_TABLE, "Table {}.{} doesn't exist",
+                    backQuoteIfNeed(getDatabaseName()), backQuoteIfNeed(name));
+}
+
+StoragePtr DatabaseFilesystem::tryGetTable(const String & name, ContextPtr context_) const
+{
+    try
+    {
+        return getTableImpl(name, context_);
+    }
+    catch (const Exception & e)
+    {
+        /// Ignore exceptions thrown by TableFunctionFile, which indicate that there is no table
+        /// see tests/02722_database_filesystem.sh for more details.
+        if (e.code() == ErrorCodes::FILE_DOESNT_EXIST)
+        {
+            return nullptr;
+        }
+        throw;
+    }
+}
+
+bool DatabaseFilesystem::empty() const
+{
+    std::lock_guard lock(mutex);
+    return loaded_tables.empty();
+}
+
+ASTPtr DatabaseFilesystem::getCreateDatabaseQuery() const
+{
+    const auto & settings = getContext()->getSettingsRef();
+    const String query = fmt::format("CREATE DATABASE {} ENGINE = Filesystem('{}')", backQuoteIfNeed(getDatabaseName()), path);
+
+    ParserCreateQuery parser;
+    ASTPtr ast = parseQuery(parser, query.data(), query.data() + query.size(), "", 0, settings.max_parser_depth);
+
+    if (const auto database_comment = getDatabaseComment(); !database_comment.empty())
+    {
+        auto & ast_create_query = ast->as<ASTCreateQuery &>();
+        ast_create_query.set(ast_create_query.comment, std::make_shared<ASTLiteral>(database_comment));
+    }
+
+    return ast;
+}
+
+void DatabaseFilesystem::shutdown()
+{
+    Tables tables_snapshot;
+    {
+        std::lock_guard lock(mutex);
+        tables_snapshot = loaded_tables;
+    }
+
+    for (const auto & kv : tables_snapshot)
+    {
+        auto table_id = kv.second->getStorageID();
+        kv.second->flushAndShutdown();
+    }
+
+    std::lock_guard lock(mutex);
+    loaded_tables.clear();
+}
+
+/**
+ * Returns an empty vector because the database is read-only and no tables can be backed up
+ */
+std::vector<std::pair<ASTPtr, StoragePtr>> DatabaseFilesystem::getTablesForBackup(const FilterByNameFunction &, const ContextPtr &) const
+{
+    return {};
+}
+
+/**
+ *
+ * Returns an empty iterator because the database does not have its own tables
+ * But only caches them for quick access
+ */
+DatabaseTablesIteratorPtr DatabaseFilesystem::getTablesIterator(ContextPtr, const FilterByNameFunction &) const
+{
+    return std::make_unique<DatabaseTablesSnapshotIterator>(Tables{}, getDatabaseName());
+}
+
+}

src/Databases/DatabaseFilesystem.h

@@ -0,0 +1,67 @@
+#pragma once
+
+#include <mutex>
+#include <Databases/IDatabase.h>
+#include <Parsers/IAST.h>
+#include <Storages/IStorage_fwd.h>
+#include <base/types.h>
+
+namespace DB
+{
+
+class Context;
+
+/**
+  * DatabaseFilesystem allows to interact with files stored on the local filesystem.
+  * Uses TableFunctionFile to implicitly load file when a user requests the table,
+  * and provides a read-only access to the data in the file.
+  * Tables are cached inside the database for quick access
+  *
+  * Used in clickhouse-local to access local files.
+  * For clickhouse-server requires allows to access file only from user_files directory.
+  */
+class DatabaseFilesystem : public IDatabase, protected WithContext
+{
+public:
+    DatabaseFilesystem(const String & name, const String & path, ContextPtr context);
+
+    String getEngineName() const override { return "Filesystem"; }
+
+    bool isTableExist(const String & name, ContextPtr context) const override;
+
+    StoragePtr getTable(const String & name, ContextPtr context) const override;
+
+    StoragePtr tryGetTable(const String & name, ContextPtr context) const override;
+
+    bool shouldBeEmptyOnDetach() const override { return false; } /// Contains only temporary tables.
+
+    bool empty() const override;
+
+    bool isReadOnly() const override { return true; }
+
+    ASTPtr getCreateDatabaseQuery() const override;
+
+    void shutdown() override;
+
+    std::vector<std::pair<ASTPtr, StoragePtr>> getTablesForBackup(const FilterByNameFunction &, const ContextPtr &) const override;
+
+    DatabaseTablesIteratorPtr getTablesIterator(ContextPtr, const FilterByNameFunction &) const override;
+
+protected:
+    StoragePtr getTableImpl(const String & name, ContextPtr context) const;
+
+    StoragePtr tryGetTableFromCache(const std::string & name) const;
+
+    std::string getTablePath(const std::string & table_name) const;
+
+    void addTable(const std::string & table_name, StoragePtr table_storage) const;
+
+    bool checkTableFilePath(const std::string & table_path, ContextPtr context_, bool throw_on_error) const;
+
+private:
+    String path;
+    mutable Tables loaded_tables TSA_GUARDED_BY(mutex);
+    Poco::Logger * log;
+};
+
+}

src/Databases/DatabaseHDFS.cpp

@@ -0,0 +1,234 @@
+#include "config.h"
+
+#if USE_HDFS
+
+#include <Databases/DatabaseHDFS.h>
+
+#include <Interpreters/Context.h>
+#include <Parsers/ASTCreateQuery.h>
+#include <Parsers/ASTFunction.h>
+#include <Parsers/ASTLiteral.h>
+#include <Parsers/parseQuery.h>
+#include <Parsers/ParserCreateQuery.h>
+#include <Storages/HDFS/HDFSCommon.h>
+#include <Storages/IStorage.h>
+#include <TableFunctions/TableFunctionFactory.h>
+
+#include <Poco/URI.h>
+#include <re2/re2.h>
+
+#include <filesystem>
+
+namespace fs = std::filesystem;
+
+namespace DB
+{
+
+namespace ErrorCodes
+{
+    extern const int LOGICAL_ERROR;
+    extern const int UNKNOWN_TABLE;
+    extern const int BAD_ARGUMENTS;
+    extern const int FILE_DOESNT_EXIST;
+    extern const int UNACCEPTABLE_URL;
+    extern const int ACCESS_DENIED;
+    extern const int DATABASE_ACCESS_DENIED;
+    extern const int HDFS_ERROR;
+    extern const int CANNOT_EXTRACT_TABLE_STRUCTURE;
+}
+
+static constexpr std::string_view HDFS_HOST_REGEXP = "^hdfs://[^/]*";
+
+
+DatabaseHDFS::DatabaseHDFS(const String & name_, const String & source_url, ContextPtr context_)
+    : IDatabase(name_)
+    , WithContext(context_->getGlobalContext())
+    , source(source_url)
+    , log(&Poco::Logger::get("DatabaseHDFS(" + name_ + ")"))
+{
+    if (!source.empty())
+    {
+        if (!re2::RE2::FullMatch(source, std::string(HDFS_HOST_REGEXP)))
+            throw Exception(ErrorCodes::BAD_ARGUMENTS, "Bad hdfs host: {}. "
+                            "It should have structure 'hdfs://<host_name>:<port>'", source);
+
+        context_->getGlobalContext()->getRemoteHostFilter().checkURL(Poco::URI(source));
+    }
+}
+
+void DatabaseHDFS::addTable(const std::string & table_name, StoragePtr table_storage) const
+{
+    std::lock_guard lock(mutex);
+    auto [_, inserted] = loaded_tables.emplace(table_name, table_storage);
+    if (!inserted)
+        throw Exception(
+            ErrorCodes::LOGICAL_ERROR,
+            "Table with name `{}` already exists in database `{}` (engine {})",
+            table_name, getDatabaseName(), getEngineName());
+}
+
+std::string DatabaseHDFS::getTablePath(const std::string & table_name) const
+{
+    if (table_name.starts_with("hdfs://"))
+        return table_name;
+
+    if (source.empty())
+        throw Exception(ErrorCodes::BAD_ARGUMENTS, "Bad hdfs url: {}. "
+                        "It should have structure 'hdfs://<host_name>:<port>/path'", table_name);
+
+    return fs::path(source) / table_name;
+}
+
+bool DatabaseHDFS::checkUrl(const std::string & url, ContextPtr context_, bool throw_on_error) const
+{
+    try
+    {
+        checkHDFSURL(url);
+        context_->getGlobalContext()->getRemoteHostFilter().checkURL(Poco::URI(url));
+    }
+    catch (...)
+    {
+        if (throw_on_error)
+            throw;
+        return false;
+    }
+
+    return true;
+}
+
+bool DatabaseHDFS::isTableExist(const String & name, ContextPtr context_) const
+{
+    std::lock_guard lock(mutex);
+    if (loaded_tables.find(name) != loaded_tables.end())
+        return true;
+
+    return checkUrl(name, context_, false);
+}
+
+StoragePtr DatabaseHDFS::getTableImpl(const String & name, ContextPtr context_) const
+{
+    /// Check if the table exists in the loaded tables map.
+    {
+        std::lock_guard lock(mutex);
+        auto it = loaded_tables.find(name);
+        if (it != loaded_tables.end())
+            return it->second;
+    }
+
+    auto url = getTablePath(name);
+
+    checkUrl(url, context_, true);
+
+    auto args = makeASTFunction("hdfs", std::make_shared<ASTLiteral>(url));
+
+    auto table_function = TableFunctionFactory::instance().get(args, context_);
+    if (!table_function)
+        return nullptr;
+
+    /// TableFunctionHDFS throws exceptions, if table cannot be created.
+    auto table_storage = table_function->execute(args, context_, name);
+    if (table_storage)
+        addTable(name, table_storage);
+
+    return table_storage;
+}
+
+StoragePtr DatabaseHDFS::getTable(const String & name, ContextPtr context_) const
+{
+    /// Rethrow all exceptions from TableFunctionHDFS to show correct error to user.
+    if (auto storage = getTableImpl(name, context_))
+        return storage;
+
+    throw Exception(ErrorCodes::UNKNOWN_TABLE, "Table {}.{} doesn't exist",
+                    backQuoteIfNeed(getDatabaseName()), backQuoteIfNeed(name));
+}
+
+StoragePtr DatabaseHDFS::tryGetTable(const String & name, ContextPtr context_) const
+{
+    try
+    {
+        return getTableImpl(name, context_);
+    }
+    catch (const Exception & e)
+    {
+        // Ignore exceptions thrown by TableFunctionHDFS, which indicate that there is no table
+        if (e.code() == ErrorCodes::BAD_ARGUMENTS
+            || e.code() == ErrorCodes::ACCESS_DENIED
+            || e.code() == ErrorCodes::DATABASE_ACCESS_DENIED
+            || e.code() == ErrorCodes::FILE_DOESNT_EXIST
+            || e.code() == ErrorCodes::UNACCEPTABLE_URL
+            || e.code() == ErrorCodes::HDFS_ERROR
+            || e.code() == ErrorCodes::CANNOT_EXTRACT_TABLE_STRUCTURE)
+        {
+            return nullptr;
+        }
+        throw;
+    }
+    catch (const Poco::URISyntaxException &)
+    {
+        return nullptr;
+    }
+}
+
+bool DatabaseHDFS::empty() const
+{
+    std::lock_guard lock(mutex);
+    return loaded_tables.empty();
+}
+
+ASTPtr DatabaseHDFS::getCreateDatabaseQuery() const
+{
+    const auto & settings = getContext()->getSettingsRef();
+    ParserCreateQuery parser;
+
+    const String query = fmt::format("CREATE DATABASE {} ENGINE = HDFS('{}')", backQuoteIfNeed(getDatabaseName()), source);
+    ASTPtr ast = parseQuery(parser, query.data(), query.data() + query.size(), "", 0, settings.max_parser_depth);
+
+    if (const auto database_comment = getDatabaseComment(); !database_comment.empty())
+    {
+        auto & ast_create_query = ast->as<ASTCreateQuery &>();
+        ast_create_query.set(ast_create_query.comment, std::make_shared<ASTLiteral>(database_comment));
+    }
+
+    return ast;
+}
+
+void DatabaseHDFS::shutdown()
+{
+    Tables tables_snapshot;
+    {
+        std::lock_guard lock(mutex);
+        tables_snapshot = loaded_tables;
+    }
+
+    for (const auto & kv : tables_snapshot)
+    {
+        auto table_id = kv.second->getStorageID();
+        kv.second->flushAndShutdown();
+    }
+
+    std::lock_guard lock(mutex);
+    loaded_tables.clear();
+}
+
+/**
+ * Returns an empty vector because the database is read-only and no tables can be backed up
+ */
+std::vector<std::pair<ASTPtr, StoragePtr>> DatabaseHDFS::getTablesForBackup(const FilterByNameFunction &, const ContextPtr &) const
+{
+    return {};
+}
+
+/**
+ *
+ * Returns an empty iterator because the database does not have its own tables
+ * But only caches them for quick access
+ */
+DatabaseTablesIteratorPtr DatabaseHDFS::getTablesIterator(ContextPtr, const FilterByNameFunction &) const
+{
+    return std::make_unique<DatabaseTablesSnapshotIterator>(Tables{}, getDatabaseName());
+}
+
+} // DB
+
+#endif

src/Databases/DatabaseHDFS.h

@@ -0,0 +1,68 @@
+#pragma once
+
+#include "config.h"
+
+#if USE_HDFS
+
+#include <mutex>
+#include <Databases/IDatabase.h>
+#include <Parsers/IAST.h>
+#include <Storages/IStorage_fwd.h>
+#include <base/types.h>
+
+namespace DB
+{
+
+class Context;
+
+/**
+  * DatabaseHDFS allows to interact with files stored on the file system.
+  * Uses TableFunctionHDFS to implicitly load file when a user requests the table,
+  * and provides read-only access to the data in the file.
+  * Tables are cached inside the database for quick access.
+  */
+class DatabaseHDFS : public IDatabase, protected WithContext
+{
+public:
+    DatabaseHDFS(const String & name, const String & source_url, ContextPtr context);
+
+    String getEngineName() const override { return "S3"; }
+
+    bool isTableExist(const String & name, ContextPtr context) const override;
+
+    StoragePtr getTable(const String & name, ContextPtr context) const override;
+
+    StoragePtr tryGetTable(const String & name, ContextPtr context) const override;
+
+    bool shouldBeEmptyOnDetach() const override { return false; } /// Contains only temporary tables.
+
+    bool empty() const override;
+
+    bool isReadOnly() const override { return true; }
+
+    ASTPtr getCreateDatabaseQuery() const override;
+
+    void shutdown() override;
+
+    std::vector<std::pair<ASTPtr, StoragePtr>> getTablesForBackup(const FilterByNameFunction &, const ContextPtr &) const override;
+    DatabaseTablesIteratorPtr getTablesIterator(ContextPtr, const FilterByNameFunction &) const override;
+
+protected:
+    StoragePtr getTableImpl(const String & name, ContextPtr context) const;
+
+    void addTable(const std::string & table_name, StoragePtr table_storage) const;
+
+    bool checkUrl(const std::string & url, ContextPtr context_, bool throw_on_error) const;
+
+    std::string getTablePath(const std::string & table_name) const;
+
+private:
+    const String source;
+
+    mutable Tables loaded_tables TSA_GUARDED_BY(mutex);
+    Poco::Logger * log;
+};
+
+}
+
+#endif

src/Databases/DatabaseS3.cpp

@@ -0,0 +1,312 @@
+#include "config.h"
+
+#if USE_AWS_S3
+
+#include <Databases/DatabaseS3.h>
+
+#include <Interpreters/Context.h>
+#include <Interpreters/evaluateConstantExpression.h>
+#include <IO/S3/URI.h>
+#include <Parsers/ASTCreateQuery.h>
+#include <Parsers/ASTFunction.h>
+#include <Parsers/ASTLiteral.h>
+#include <Parsers/parseQuery.h>
+#include <Parsers/ParserCreateQuery.h>
+#include <Storages/checkAndGetLiteralArgument.h>
+#include <Storages/IStorage.h>
+#include <Storages/NamedCollectionsHelpers.h>
+#include <TableFunctions/TableFunctionFactory.h>
+
+#include <boost/algorithm/string.hpp>
+#include <filesystem>
+
+namespace fs = std::filesystem;
+
+namespace DB
+{
+
+static const std::unordered_set<std::string_view> optional_configuration_keys = {
+    "url",
+    "access_key_id",
+    "secret_access_key",
+    "no_sign_request"
+};
+
+namespace ErrorCodes
+{
+    extern const int LOGICAL_ERROR;
+    extern const int UNKNOWN_TABLE;
+    extern const int BAD_ARGUMENTS;
+    extern const int FILE_DOESNT_EXIST;
+    extern const int UNACCEPTABLE_URL;
+    extern const int S3_ERROR;
+
+    extern const int NUMBER_OF_ARGUMENTS_DOESNT_MATCH;
+}
+
+DatabaseS3::DatabaseS3(const String & name_, const Configuration& config_, ContextPtr context_)
+    : IDatabase(name_)
+    , WithContext(context_->getGlobalContext())
+    , config(config_)
+    , log(&Poco::Logger::get("DatabaseS3(" + name_ + ")"))
+{
+}
+
+void DatabaseS3::addTable(const std::string & table_name, StoragePtr table_storage) const
+{
+    std::lock_guard lock(mutex);
+    auto [_, inserted] = loaded_tables.emplace(table_name, table_storage);
+    if (!inserted)
+        throw Exception(
+            ErrorCodes::LOGICAL_ERROR,
+            "Table with name `{}` already exists in database `{}` (engine {})",
+            table_name, getDatabaseName(), getEngineName());
+}
+
+std::string DatabaseS3::getFullUrl(const std::string & name) const
+{
+    if (!config.url_prefix.empty())
+        return fs::path(config.url_prefix) / name;
+
+    return name;
+}
+
+bool DatabaseS3::checkUrl(const std::string & url, ContextPtr context_, bool throw_on_error) const
+{
+    try
+    {
+        S3::URI uri(url);
+        context_->getGlobalContext()->getRemoteHostFilter().checkURL(uri.uri);
+    }
+    catch (...)
+    {
+        if (throw_on_error)
+            throw;
+        return false;
+    }
+    return true;
+}
+
+bool DatabaseS3::isTableExist(const String & name, ContextPtr context_) const
+{
+    std::lock_guard lock(mutex);
+    if (loaded_tables.find(name) != loaded_tables.end())
+        return true;
+
+    return checkUrl(getFullUrl(name), context_, false);
+}
+
+StoragePtr DatabaseS3::getTableImpl(const String & name, ContextPtr context_) const
+{
+    /// Check if the table exists in the loaded tables map.
+    {
+        std::lock_guard lock(mutex);
+        auto it = loaded_tables.find(name);
+        if (it != loaded_tables.end())
+            return it->second;
+    }
+
+    auto url = getFullUrl(name);
+    checkUrl(url, context_, /* throw_on_error */true);
+
+    auto function = std::make_shared<ASTFunction>();
+    function->name = "s3";
+    function->arguments = std::make_shared<ASTExpressionList>();
+    function->children.push_back(function->arguments);
+
+    function->arguments->children.push_back(std::make_shared<ASTLiteral>(url));
+    if (config.no_sign_request)
+    {
+        function->arguments->children.push_back(std::make_shared<ASTLiteral>("NOSIGN"));
+    }
+    else if (config.access_key_id.has_value() && config.secret_access_key.has_value())
+    {
+        function->arguments->children.push_back(std::make_shared<ASTLiteral>(config.access_key_id.value()));
+        function->arguments->children.push_back(std::make_shared<ASTLiteral>(config.secret_access_key.value()));
+    }
+
+    auto table_function = TableFunctionFactory::instance().get(function, context_);
+    if (!table_function)
+        return nullptr;
+
+    /// TableFunctionS3 throws exceptions, if table cannot be created.
+    auto table_storage = table_function->execute(function, context_, name);
+    if (table_storage)
+        addTable(name, table_storage);
+
+    return table_storage;
+}
+
+StoragePtr DatabaseS3::getTable(const String & name, ContextPtr context_) const
+{
+    /// Rethrow all exceptions from TableFunctionS3 to show correct error to user.
+    if (auto storage = getTableImpl(name, context_))
+        return storage;
+
+    throw Exception(ErrorCodes::UNKNOWN_TABLE, "Table {}.{} doesn't exist",
+                    backQuoteIfNeed(getDatabaseName()), backQuoteIfNeed(name));
+}
+
+StoragePtr DatabaseS3::tryGetTable(const String & name, ContextPtr context_) const
+{
+    try
+    {
+        return getTableImpl(name, context_);
+    }
+    catch (const Exception & e)
+    {
+        /// Ignore exceptions thrown by TableFunctionS3, which indicate that there is no table.
+        if (e.code() == ErrorCodes::BAD_ARGUMENTS
+            || e.code() == ErrorCodes::S3_ERROR
+            || e.code() == ErrorCodes::FILE_DOESNT_EXIST
+            || e.code() == ErrorCodes::UNACCEPTABLE_URL)
+        {
+            return nullptr;
+        }
+        throw;
+    }
+    catch (const Poco::URISyntaxException &)
+    {
+        return nullptr;
+    }
+}
+
+bool DatabaseS3::empty() const
+{
+    std::lock_guard lock(mutex);
+    return loaded_tables.empty();
+}
+
+ASTPtr DatabaseS3::getCreateDatabaseQuery() const
+{
+    const auto & settings = getContext()->getSettingsRef();
+    ParserCreateQuery parser;
+
+    std::string creation_args;
+    creation_args += fmt::format("'{}'", config.url_prefix);
+    if (config.no_sign_request)
+        creation_args += ", 'NOSIGN'";
+    else if (config.access_key_id.has_value() && config.secret_access_key.has_value())
+        creation_args += fmt::format(", '{}', '{}'", config.access_key_id.value(), config.secret_access_key.value());
+
+    const String query = fmt::format("CREATE DATABASE {} ENGINE = S3({})", backQuoteIfNeed(getDatabaseName()), creation_args);
+    ASTPtr ast = parseQuery(parser, query.data(), query.data() + query.size(), "", 0, settings.max_parser_depth);
+
+    if (const auto database_comment = getDatabaseComment(); !database_comment.empty())
+    {
+        auto & ast_create_query = ast->as<ASTCreateQuery &>();
+        ast_create_query.set(ast_create_query.comment, std::make_shared<ASTLiteral>(database_comment));
+    }
+
+    return ast;
+}
+
+void DatabaseS3::shutdown()
+{
+    Tables tables_snapshot;
+    {
+        std::lock_guard lock(mutex);
+        tables_snapshot = loaded_tables;
+    }
+
+    for (const auto & kv : tables_snapshot)
+    {
+        auto table_id = kv.second->getStorageID();
+        kv.second->flushAndShutdown();
+    }
+
+    std::lock_guard lock(mutex);
+    loaded_tables.clear();
+}
+
+DatabaseS3::Configuration DatabaseS3::parseArguments(ASTs engine_args, ContextPtr context_)
+{
+    Configuration result;
+
+    if (auto named_collection = tryGetNamedCollectionWithOverrides(engine_args, context_))
+    {
+        auto & collection = *named_collection;
+
+        validateNamedCollection(collection, {}, optional_configuration_keys);
+
+        result.url_prefix = collection.getOrDefault<String>("url", "");
+        result.no_sign_request = collection.getOrDefault<bool>("no_sign_request", false);
+
+        auto key_id = collection.getOrDefault<String>("access_key_id", "");
+        auto secret_key = collection.getOrDefault<String>("secret_access_key", "");
+
+        if (!key_id.empty())
+            result.access_key_id = key_id;
+
+        if (!secret_key.empty())
+            result.secret_access_key = secret_key;
+    }
+    else
+    {
+        const std::string supported_signature =
+            " - S3()\n"
+            " - S3('url')\n"
+            " - S3('url', 'NOSIGN')\n"
+            " - S3('url', 'access_key_id', 'secret_access_key')\n";
+        const auto error_message =
+            fmt::format("Engine DatabaseS3 must have the following arguments signature\n{}", supported_signature);
+
+        for (auto & arg : engine_args)
+            arg = evaluateConstantExpressionOrIdentifierAsLiteral(arg, context_);
+
+        if (engine_args.size() > 3)
+            throw Exception(ErrorCodes::NUMBER_OF_ARGUMENTS_DOESNT_MATCH, error_message.c_str());
+
+        if (engine_args.empty())
+            return result;
+
+        result.url_prefix = checkAndGetLiteralArgument<String>(engine_args[0], "url");
+
+        // url, NOSIGN
+        if (engine_args.size() == 2)
+        {
+            auto second_arg = checkAndGetLiteralArgument<String>(engine_args[1], "NOSIGN");
+            if (boost::iequals(second_arg, "NOSIGN"))
+                result.no_sign_request = true;
+            else
+                throw Exception(ErrorCodes::BAD_ARGUMENTS, error_message.c_str());
+        }
+
+        // url, access_key_id, secret_access_key
+        if (engine_args.size() == 3)
+        {
+            auto key_id = checkAndGetLiteralArgument<String>(engine_args[1], "access_key_id");
+            auto secret_key = checkAndGetLiteralArgument<String>(engine_args[2], "secret_access_key");
+
+            if (key_id.empty() || secret_key.empty() || boost::iequals(key_id, "NOSIGN"))
+                throw Exception(ErrorCodes::BAD_ARGUMENTS, error_message.c_str());
+
+            result.access_key_id = key_id;
+            result.secret_access_key = secret_key;
+        }
+    }
+
+    return result;
+}
+
+/**
+ * Returns an empty vector because the database is read-only and no tables can be backed up
+ */
+std::vector<std::pair<ASTPtr, StoragePtr>> DatabaseS3::getTablesForBackup(const FilterByNameFunction &, const ContextPtr &) const
+{
+    return {};
+}
+
+/**
+ *
+ * Returns an empty iterator because the database does not have its own tables
+ * But only caches them for quick access
+ */
+DatabaseTablesIteratorPtr DatabaseS3::getTablesIterator(ContextPtr, const FilterByNameFunction &) const
+{
+    return std::make_unique<DatabaseTablesSnapshotIterator>(Tables{}, getDatabaseName());
+}
+
+}
+
+#endif

src/Databases/DatabaseS3.h

@@ -0,0 +1,81 @@
+#pragma once
+
+#include "config.h"
+
+#if USE_AWS_S3
+
+#include <mutex>
+#include <Databases/IDatabase.h>
+#include <Parsers/IAST.h>
+#include <Storages/IStorage_fwd.h>
+#include <base/types.h>
+
+namespace DB
+{
+
+class Context;
+
+/**
+  * DatabaseS3 provides access to data stored in S3.
+  * Uses TableFunctionS3 to implicitly load file when a user requests the table,
+  * and provides read-only access to the data in the file.
+  * Tables are cached inside the database for quick access.
+  */
+class DatabaseS3 : public IDatabase, protected WithContext
+{
+public:
+    struct Configuration
+    {
+        std::string url_prefix;
+
+        bool no_sign_request = false;
+
+        std::optional<std::string> access_key_id;
+        std::optional<std::string> secret_access_key;
+    };
+
+    DatabaseS3(const String & name, const Configuration& config, ContextPtr context);
+
+    String getEngineName() const override { return "S3"; }
+
+    bool isTableExist(const String & name, ContextPtr context) const override;
+
+    StoragePtr getTable(const String & name, ContextPtr context) const override;
+
+    StoragePtr tryGetTable(const String & name, ContextPtr context) const override;
+
+    // Contains only temporary tables
+    bool shouldBeEmptyOnDetach() const override { return false; }
+
+    bool empty() const override;
+
+    bool isReadOnly() const override { return true; }
+
+    ASTPtr getCreateDatabaseQuery() const override;
+
+    void shutdown() override;
+
+    std::vector<std::pair<ASTPtr, StoragePtr>> getTablesForBackup(const FilterByNameFunction &, const ContextPtr &) const override;
+    DatabaseTablesIteratorPtr getTablesIterator(ContextPtr, const FilterByNameFunction &) const override;
+
+    static Configuration parseArguments(ASTs engine_args, ContextPtr context);
+
+protected:
+    StoragePtr getTableImpl(const String & name, ContextPtr context) const;
+
+    void addTable(const std::string & table_name, StoragePtr table_storage) const;
+
+    bool checkUrl(const std::string & url, ContextPtr context_, bool throw_on_error) const;
+
+    std::string getFullUrl(const std::string & name) const;
+
+private:
+    const Configuration config;
+
+    mutable Tables loaded_tables TSA_GUARDED_BY(mutex);
+    Poco::Logger * log;
+};
+
+}
+
+#endif

src/Databases/DatabasesOverlay.cpp

@@ -0,0 +1,266 @@
+#include <Databases/DatabasesOverlay.h>
+
+#include <Common/typeid_cast.h>
+#include <Interpreters/Context.h>
+#include <Interpreters/InterpreterCreateQuery.h>
+#include <Parsers/ASTCreateQuery.h>
+
+#include <Storages/IStorage_fwd.h>
+
+namespace DB
+{
+
+namespace ErrorCodes
+{
+    extern const int LOGICAL_ERROR;
+    extern const int CANNOT_GET_CREATE_TABLE_QUERY;
+}
+
+DatabasesOverlay::DatabasesOverlay(const String & name_, ContextPtr context_)
+    : IDatabase(name_), WithContext(context_->getGlobalContext()), log(&Poco::Logger::get("DatabaseOverlay(" + name_ + ")"))
+{
+}
+
+DatabasesOverlay & DatabasesOverlay::registerNextDatabase(DatabasePtr database)
+{
+    databases.push_back(std::move(database));
+    return *this;
+}
+
+bool DatabasesOverlay::isTableExist(const String & table_name, ContextPtr context_) const
+{
+    for (const auto & db : databases)
+    {
+        if (db->isTableExist(table_name, context_))
+            return true;
+    }
+    return false;
+}
+
+StoragePtr DatabasesOverlay::tryGetTable(const String & table_name, ContextPtr context_) const
+{
+    StoragePtr result = nullptr;
+    for (const auto & db : databases)
+    {
+        result = db->tryGetTable(table_name, context_);
+        if (result)
+            break;
+    }
+    return result;
+}
+
+void DatabasesOverlay::createTable(ContextPtr context_, const String & table_name, const StoragePtr & table, const ASTPtr & query)
+{
+    for (auto & db : databases)
+    {
+        if (!db->isReadOnly())
+        {
+            db->createTable(context_, table_name, table, query);
+            return;
+        }
+    }
+    throw Exception(
+        ErrorCodes::LOGICAL_ERROR,
+        "There is no databases for CREATE TABLE `{}` query in database `{}` (engine {})",
+        table_name,
+        getDatabaseName(),
+        getEngineName());
+}
+
+void DatabasesOverlay::dropTable(ContextPtr context_, const String & table_name, bool sync)
+{
+    for (auto & db : databases)
+    {
+        if (db->isTableExist(table_name, context_))
+        {
+            db->dropTable(context_, table_name, sync);
+            return;
+        }
+    }
+    throw Exception(
+        ErrorCodes::LOGICAL_ERROR,
+        "There is no databases for DROP TABLE `{}` query in database `{}` (engine {})",
+        table_name,
+        getDatabaseName(),
+        getEngineName());
+}
+
+void DatabasesOverlay::attachTable(
+    ContextPtr context_, const String & table_name, const StoragePtr & table, const String & relative_table_path)
+{
+    for (auto & db : databases)
+    {
+        try
+        {
+            db->attachTable(context_, table_name, table, relative_table_path);
+            return;
+        }
+        catch (...)
+        {
+            continue;
+        }
+    }
+    throw Exception(
+        ErrorCodes::LOGICAL_ERROR,
+        "There is no databases for ATTACH TABLE `{}` query in database `{}` (engine {})",
+        table_name,
+        getDatabaseName(),
+        getEngineName());
+}
+
+StoragePtr DatabasesOverlay::detachTable(ContextPtr context_, const String & table_name)
+{
+    StoragePtr result = nullptr;
+    for (auto & db : databases)
+    {
+        if (db->isTableExist(table_name, context_))
+            return db->detachTable(context_, table_name);
+    }
+    throw Exception(
+        ErrorCodes::LOGICAL_ERROR,
+        "There is no databases for DETACH TABLE `{}` query in database `{}` (engine {})",
+        table_name,
+        getDatabaseName(),
+        getEngineName());
+}
+
+ASTPtr DatabasesOverlay::getCreateTableQueryImpl(const String & name, ContextPtr context_, bool throw_on_error) const
+{
+    ASTPtr result = nullptr;
+    for (const auto & db : databases)
+    {
+        result = db->tryGetCreateTableQuery(name, context_);
+        if (result)
+            break;
+    }
+    if (!result && throw_on_error)
+        throw Exception(
+            ErrorCodes::CANNOT_GET_CREATE_TABLE_QUERY,
+            "There is no metadata of table `{}` in database `{}` (engine {})",
+            name,
+            getDatabaseName(),
+            getEngineName());
+    return result;
+}
+
+/*
+ * DatabaseOverlay cannot be constructed by "CREATE DATABASE" query, as it is not a traditional ClickHouse database
+ * To use DatabaseOverlay, it must be constructed programmatically in code
+ */
+ASTPtr DatabasesOverlay::getCreateDatabaseQuery() const
+{
+    return std::make_shared<ASTCreateQuery>();
+}
+
+String DatabasesOverlay::getTableDataPath(const String & table_name) const
+{
+    String result;
+    for (const auto & db : databases)
+    {
+        result = db->getTableDataPath(table_name);
+        if (!result.empty())
+            break;
+    }
+    return result;
+}
+
+String DatabasesOverlay::getTableDataPath(const ASTCreateQuery & query) const
+{
+    String result;
+    for (const auto & db : databases)
+    {
+        result = db->getTableDataPath(query);
+        if (!result.empty())
+            break;
+    }
+    return result;
+}
+
+UUID DatabasesOverlay::tryGetTableUUID(const String & table_name) const
+{
+    UUID result = UUIDHelpers::Nil;
+    for (const auto & db : databases)
+    {
+        result = db->tryGetTableUUID(table_name);
+        if (result != UUIDHelpers::Nil)
+            break;
+    }
+    return result;
+}
+
+void DatabasesOverlay::drop(ContextPtr context_)
+{
+    for (auto & db : databases)
+        db->drop(context_);
+}
+
+void DatabasesOverlay::alterTable(ContextPtr local_context, const StorageID & table_id, const StorageInMemoryMetadata & metadata)
+{
+    for (auto & db : databases)
+    {
+        if (!db->isReadOnly() && db->isTableExist(table_id.table_name, local_context))
+        {
+            db->alterTable(local_context, table_id, metadata);
+            return;
+        }
+    }
+    throw Exception(
+        ErrorCodes::LOGICAL_ERROR,
+        "There is no databases for ALTER TABLE `{}` query in database `{}` (engine {})",
+        table_id.table_name,
+        getDatabaseName(),
+        getEngineName());
+}
+
+std::vector<std::pair<ASTPtr, StoragePtr>>
+DatabasesOverlay::getTablesForBackup(const FilterByNameFunction & filter, const ContextPtr & local_context) const
+{
+    std::vector<std::pair<ASTPtr, StoragePtr>> result;
+    for (const auto & db : databases)
+    {
+        auto db_backup = db->getTablesForBackup(filter, local_context);
+        result.insert(result.end(), std::make_move_iterator(db_backup.begin()), std::make_move_iterator(db_backup.end()));
+    }
+    return result;
+}
+
+void DatabasesOverlay::createTableRestoredFromBackup(
+    const ASTPtr & create_table_query,
+    ContextMutablePtr local_context,
+    std::shared_ptr<IRestoreCoordination> /*restore_coordination*/,
+    UInt64 /*timeout_ms*/)
+{
+    /// Creates a tables by executing a "CREATE TABLE" query.
+    InterpreterCreateQuery interpreter{create_table_query, local_context};
+    interpreter.setInternal(true);
+    interpreter.execute();
+}
+
+bool DatabasesOverlay::empty() const
+{
+    for (const auto & db : databases)
+    {
+        if (!db->empty())
+            return false;
+    }
+    return true;
+}
+
+void DatabasesOverlay::shutdown()
+{
+    for (auto & db : databases)
+        db->shutdown();
+}
+
+DatabaseTablesIteratorPtr DatabasesOverlay::getTablesIterator(ContextPtr context_, const FilterByNameFunction & filter_by_table_name) const
+{
+    Tables tables;
+    for (const auto & db : databases)
+    {
+        for (auto table_it = db->getTablesIterator(context_, filter_by_table_name); table_it->isValid(); table_it->next())
+            tables.insert({table_it->name(), table_it->table()});
+    }
+    return std::make_unique<DatabaseTablesSnapshotIterator>(std::move(tables), getDatabaseName());
+}
+
+}

src/Databases/DatabasesOverlay.h

@@ -0,0 +1,66 @@
+#pragma once
+
+#include <Storages/IStorage_fwd.h>
+#include <Databases/IDatabase.h>
+
+namespace DB
+{
+
+/**
+ * Implements the IDatabase interface and combines multiple other databases
+ * Searches for tables in each database in order until found, and delegates operations to the appropriate database
+ * Useful for combining databases
+ *
+ * Used in clickhouse-local to combine DatabaseFileSystem and DatabaseMemory
+ */
+class DatabasesOverlay : public IDatabase, protected WithContext
+{
+public:
+    DatabasesOverlay(const String & name_, ContextPtr context_);
+
+    /// Not thread-safe. Use only as factory to initialize database
+    DatabasesOverlay & registerNextDatabase(DatabasePtr database);
+
+    String getEngineName() const override { return "Overlay"; }
+
+public:
+    bool isTableExist(const String & table_name, ContextPtr context) const override;
+
+    StoragePtr tryGetTable(const String & table_name, ContextPtr context) const override;
+
+    void createTable(ContextPtr context, const String & table_name, const StoragePtr & table, const ASTPtr & query) override;
+
+    void dropTable(ContextPtr context, const String & table_name, bool sync) override;
+
+    void attachTable(ContextPtr context, const String & table_name, const StoragePtr & table, const String & relative_table_path) override;
+
+    StoragePtr detachTable(ContextPtr context, const String & table_name) override;
+
+    ASTPtr getCreateTableQueryImpl(const String & name, ContextPtr context, bool throw_on_error) const override;
+    ASTPtr getCreateDatabaseQuery() const override;
+
+    String getTableDataPath(const String & table_name) const override;
+    String getTableDataPath(const ASTCreateQuery & query) const override;
+
+    UUID tryGetTableUUID(const String & table_name) const override;
+
+    void drop(ContextPtr context) override;
+
+    void alterTable(ContextPtr local_context, const StorageID & table_id, const StorageInMemoryMetadata & metadata) override;
+
+    std::vector<std::pair<ASTPtr, StoragePtr>> getTablesForBackup(const FilterByNameFunction & filter, const ContextPtr & local_context) const override;
+
+    void createTableRestoredFromBackup(const ASTPtr & create_table_query, ContextMutablePtr local_context, std::shared_ptr<IRestoreCoordination> restore_coordination, UInt64 timeout_ms) override;
+
+    DatabaseTablesIteratorPtr getTablesIterator(ContextPtr context, const FilterByNameFunction & filter_by_table_name) const override;
+
+    bool empty() const override;
+
+    void shutdown() override;
+
+protected:
+    std::vector<DatabasePtr> databases;
+    Poco::Logger * log;
+};
+
+}

src/Databases/IDatabase.h

@@ -170,7 +170,7 @@ public:
     /// Get the table for work. Return nullptr if there is no table.
     virtual StoragePtr tryGetTable(const String & name, ContextPtr context) const = 0;
 
-    StoragePtr getTable(const String & name, ContextPtr context) const;
+    virtual StoragePtr getTable(const String & name, ContextPtr context) const;
 
     virtual UUID tryGetTableUUID(const String & /*table_name*/) const { return UUIDHelpers::Nil; }
 
@@ -183,6 +183,8 @@ public:
     /// Is the database empty.
     virtual bool empty() const = 0;
 
+    virtual bool isReadOnly() const { return false; }
+
     /// Add the table to the database. Record its presence in the metadata.
     virtual void createTable(
         ContextPtr /*context*/,

src/Dictionaries/RegExpTreeDictionary.cpp

@@ -30,8 +30,6 @@
 #include <Dictionaries/RegExpTreeDictionary.h>
 #include <Dictionaries/YAMLRegExpTreeDictionarySource.h>
 
-#include <re2_st/stringpiece.h>
-
 #include "config.h"
 
 #if USE_VECTORSCAN
@@ -469,10 +467,9 @@ public:
 
 std::pair<String, bool> processBackRefs(const String & data, const re2_st::RE2 & searcher, const std::vector<StringPiece> & pieces)
 {
-    re2_st::StringPiece haystack(data.data(), data.size());
-    re2_st::StringPiece matches[10];
+    std::string_view matches[10];
     String result;
-    searcher.Match(haystack, 0, data.size(), re2_st::RE2::Anchor::UNANCHORED, matches, 10);
+    searcher.Match({data.data(), data.size()}, 0, data.size(), re2_st::RE2::Anchor::UNANCHORED, matches, 10);
     /// if the pattern is a single '$1' but fails to match, we would use the default value.
     if (pieces.size() == 1 && pieces[0].ref_num >= 0 && pieces[0].ref_num < 10 && matches[pieces[0].ref_num].empty())
         return std::make_pair(result, true);

src/Functions/ReplaceRegexpImpl.h

@@ -99,8 +99,8 @@ struct ReplaceRegexpImpl
         int num_captures,
         const Instructions & instructions)
     {
-        re2_st::StringPiece haystack(haystack_data, haystack_length);
-        re2_st::StringPiece matches[max_captures];
+        std::string_view haystack(haystack_data, haystack_length);
+        std::string_view matches[max_captures];
 
         size_t copy_pos = 0;
         size_t match_pos = 0;

src/Functions/checkHyperscanRegexp.cpp

@@ -45,8 +45,8 @@ bool isLargerThanFifty(std::string_view str)
 /// Check for sub-patterns of the form x{n} or x{n,} can be expensive. Ignore spaces before/after n and m.
 bool SlowWithHyperscanChecker::isSlowOneRepeat(std::string_view regexp)
 {
-    re2_st::StringPiece haystack(regexp.data(), regexp.size());
-    re2_st::StringPiece matches[2];
+    std::string_view haystack(regexp.data(), regexp.size());
+    std::string_view matches[2];
     size_t start_pos = 0;
     while (start_pos < haystack.size())
     {
@@ -67,8 +67,8 @@ bool SlowWithHyperscanChecker::isSlowOneRepeat(std::string_view regexp)
 /// Check if sub-patterns of the form x{n,m} can be expensive. Ignore spaces before/after n and m.
 bool SlowWithHyperscanChecker::isSlowTwoRepeats(std::string_view regexp)
 {
-    re2_st::StringPiece haystack(regexp.data(), regexp.size());
-    re2_st::StringPiece matches[3];
+    std::string_view haystack(regexp.data(), regexp.size());
+    std::string_view matches[3];
     size_t start_pos = 0;
     while (start_pos < haystack.size())
     {

src/Functions/extractAllGroups.h

@@ -94,7 +94,6 @@ public:
         if (needle.empty())
             throw Exception(ErrorCodes::BAD_ARGUMENTS, "Length of 'needle' argument must be greater than 0.");
 
-        using StringPiece = typename Regexps::Regexp::StringPieceType;
         const Regexps::Regexp holder = Regexps::createRegexp<false, false, false>(needle);
         const auto & regexp = holder.getRE2();
 
@@ -111,7 +110,7 @@ public:
                             groups_count, std::to_string(MAX_GROUPS_COUNT - 1));
 
         // Including 0-group, which is the whole regexp.
-        PODArrayWithStackMemory<StringPiece, MAX_GROUPS_COUNT> matched_groups(groups_count + 1);
+        PODArrayWithStackMemory<std::string_view, MAX_GROUPS_COUNT> matched_groups(groups_count + 1);
 
         ColumnArray::ColumnOffsets::MutablePtr root_offsets_col = ColumnArray::ColumnOffsets::create();
         ColumnArray::ColumnOffsets::MutablePtr nested_offsets_col = ColumnArray::ColumnOffsets::create();
@@ -160,7 +159,7 @@ public:
             /// Additional limit to fail fast on supposedly incorrect usage.
             const auto max_matches_per_row = context->getSettingsRef().regexp_max_matches_per_row;
 
-            PODArray<StringPiece, 0> all_matches;
+            PODArray<std::string_view, 0> all_matches;
             /// Number of times RE matched on each row of haystack column.
             PODArray<size_t, 0> number_of_matches_per_row;
 

src/Functions/extractGroups.cpp

@@ -75,7 +75,7 @@ public:
             throw Exception(ErrorCodes::BAD_ARGUMENTS, "There are no groups in regexp: {}", needle);
 
         // Including 0-group, which is the whole regexp.
-        PODArrayWithStackMemory<re2_st::StringPiece, 128> matched_groups(groups_count + 1);
+        PODArrayWithStackMemory<std::string_view, 128> matched_groups(groups_count + 1);
 
         ColumnArray::ColumnOffsets::MutablePtr offsets_col = ColumnArray::ColumnOffsets::create();
         ColumnString::MutablePtr data_col = ColumnString::create();
@@ -89,7 +89,7 @@ public:
         {
             std::string_view current_row = column_haystack->getDataAt(i).toView();
 
-            if (re2->Match(re2_st::StringPiece(current_row.data(), current_row.size()),
+            if (re2->Match({current_row.data(), current_row.size()},
                 0, current_row.size(), re2_st::RE2::UNANCHORED, matched_groups.data(),
                 static_cast<int>(matched_groups.size())))
             {

src/Interpreters/DatabaseCatalog.cpp

@@ -357,6 +357,7 @@ DatabaseAndTable DatabaseCatalog::getTableImpl(
     auto table = database->tryGetTable(table_id.table_name, context_);
     if (!table && exception)
         exception->emplace(Exception(ErrorCodes::UNKNOWN_TABLE, "Table {} doesn't exist", table_id.getNameForLogs()));
+
     if (!table)
         database = nullptr;
 

src/Interpreters/FilesystemCacheLog.h

@@ -11,16 +11,7 @@
 
 namespace DB
 {
-///
-/// -------- Column --------- Type ------
-/// |  event_date         |  DateTime   |
-/// |  event_time         |  UInt64     |
-/// |  query_id           |  String     |
-/// |  remote_file_path   |  String     |
-/// |  segment_range      |  Tuple      |
-/// |  read_type          |  String     |
-/// -------------------------------------
-///
+
 struct FilesystemCacheLogElement
 {
     enum class CacheType

src/Interpreters/InterpreterSystemQuery.cpp

@@ -370,15 +370,15 @@ BlockIO InterpreterSystemQuery::execute()
             else
             {
                 auto cache = FileCacheFactory::instance().getByName(query.filesystem_cache_name).cache;
-                if (query.delete_key.empty())
+                if (query.key_to_drop.empty())
                 {
                     cache->removeAllReleasable();
                 }
                 else
                 {
-                    auto key = FileCacheKey::fromKeyString(query.delete_key);
-                    if (query.delete_offset.has_value())
-                        cache->removeFileSegment(key, query.delete_offset.value());
+                    auto key = FileCacheKey::fromKeyString(query.key_to_drop);
+                    if (query.offset_to_drop.has_value())
+                        cache->removeFileSegment(key, query.offset_to_drop.value());
                     else
                         cache->removeKey(key);
                 }

src/Parsers/ASTSystemQuery.cpp

@@ -212,11 +212,11 @@ void ASTSystemQuery::formatImpl(const FormatSettings & settings, FormatState &,
         if (!filesystem_cache_name.empty())
         {
             settings.ostr << (settings.hilite ? hilite_none : "") << " " << filesystem_cache_name;
-            if (!delete_key.empty())
+            if (!key_to_drop.empty())
             {
-                settings.ostr << (settings.hilite ? hilite_none : "") << " KEY " << delete_key;
-                if (delete_offset.has_value())
-                    settings.ostr << (settings.hilite ? hilite_none : "") << " OFFSET " << delete_offset.value();
+                settings.ostr << (settings.hilite ? hilite_none : "") << " KEY " << key_to_drop;
+                if (offset_to_drop.has_value())
+                    settings.ostr << (settings.hilite ? hilite_none : "") << " OFFSET " << offset_to_drop.value();
             }
         }
     }

src/Parsers/ASTSystemQuery.h

@@ -107,8 +107,8 @@ public:
     UInt64 seconds{};
 
     String filesystem_cache_name;
-    std::string delete_key;
-    std::optional<size_t> delete_offset;
+    std::string key_to_drop;
+    std::optional<size_t> offset_to_drop;
 
     String backup_name;
 

src/Parsers/ParserSystemQuery.cpp

@@ -409,9 +409,9 @@ bool ParserSystemQuery::parseImpl(IParser::Pos & pos, ASTPtr & node, Expected &
                 res->filesystem_cache_name = ast->as<ASTLiteral>()->value.safeGet<String>();
                 if (ParserKeyword{"KEY"}.ignore(pos, expected) && ParserIdentifier().parse(pos, ast, expected))
                 {
-                    res->delete_key = ast->as<ASTIdentifier>()->name();
+                    res->key_to_drop = ast->as<ASTIdentifier>()->name();
                     if (ParserKeyword{"OFFSET"}.ignore(pos, expected) && ParserLiteral().parse(pos, ast, expected))
-                        res->delete_offset = ast->as<ASTLiteral>()->value.safeGet<UInt64>();
+                        res->offset_to_drop = ast->as<ASTLiteral>()->value.safeGet<UInt64>();
                 }
             }
             if (!parseQueryWithOnCluster(res, pos, expected))

src/Processors/Formats/Impl/RegexpRowInputFormat.h

@@ -1,7 +1,6 @@
 #pragma once
 
 #include <re2_st/re2.h>
-#include <re2_st/stringpiece.h>
 #include <string>
 #include <vector>
 #include <Core/Block.h>
@@ -28,14 +27,14 @@ public:
     /// Return true if row was successfully parsed and row fields were extracted.
     bool parseRow(PeekableReadBuffer & buf);
 
-    re2_st::StringPiece getField(size_t index) { return matched_fields[index]; }
+    std::string_view getField(size_t index) { return matched_fields[index]; }
     size_t getMatchedFieldsSize() const { return matched_fields.size(); }
     size_t getNumberOfGroups() const { return regexp.NumberOfCapturingGroups(); }
 
 private:
     const re2_st::RE2 regexp;
     // The vector of fields extracted from line using regexp.
-    std::vector<re2_st::StringPiece> matched_fields;
+    std::vector<std::string_view> matched_fields;
     // These two vectors are needed to use RE2::FullMatchN (function for extracting fields).
     std::vector<re2_st::RE2::Arg> re2_arguments;
     std::vector<re2_st::RE2::Arg *> re2_arguments_ptrs;

src/Server/HTTPHandler.cpp

@@ -44,6 +44,8 @@
 #include <Poco/String.h>
 #include <Poco/Net/SocketAddress.h>
 
+#include <re2/re2.h>
+
 #include <chrono>
 #include <sstream>
 
@@ -1163,8 +1165,8 @@ void PredefinedQueryHandler::customizeContext(HTTPServerRequest & request, Conte
     {
         int num_captures = compiled_regex->NumberOfCapturingGroups() + 1;
 
-        re2::StringPiece matches[num_captures];
-        re2::StringPiece input(begin, end - begin);
+        std::string_view matches[num_captures];
+        std::string_view input(begin, end - begin);
         if (compiled_regex->Match(input, 0, end - begin, re2::RE2::Anchor::ANCHOR_BOTH, matches, num_captures))
         {
             for (const auto & [capturing_name, capturing_index] : compiled_regex->NamedCapturingGroups())

src/Server/HTTPHandlerRequestFilter.h

@@ -6,7 +6,6 @@
 #include <base/find_symbols.h>
 
 #include <re2/re2.h>
-#include <re2/stringpiece.h>
 #include <Poco/StringTokenizer.h>
 #include <Poco/Util/LayeredConfiguration.h>
 
@@ -26,9 +25,8 @@ static inline bool checkRegexExpression(std::string_view match_str, const Compil
 {
     int num_captures = compiled_regex->NumberOfCapturingGroups() + 1;
 
-    re2::StringPiece matches[num_captures];
-    re2::StringPiece match_input(match_str.data(), match_str.size());
-    return compiled_regex->Match(match_input, 0, match_str.size(), re2::RE2::Anchor::ANCHOR_BOTH, matches, num_captures);
+    std::string_view matches[num_captures];
+    return compiled_regex->Match({match_str.data(), match_str.size()}, 0, match_str.size(), re2::RE2::Anchor::ANCHOR_BOTH, matches, num_captures);
 }
 
 static inline bool checkExpression(std::string_view match_str, const std::pair<String, CompiledRegexPtr> & expression)

src/Storages/MergeTree/MergeTreeData.cpp

@@ -7196,7 +7196,10 @@ QueryProcessingStage::Enum MergeTreeData::getQueryProcessingStage(
     if (query_context->canUseParallelReplicasOnInitiator() && to_stage >= QueryProcessingStage::WithMergeableState)
     {
         if (!canUseParallelReplicasBasedOnPKAnalysis(query_context, storage_snapshot, query_info))
+        {
+            query_info.parallel_replicas_disabled = true;
             return QueryProcessingStage::Enum::FetchColumns;
+        }
 
         /// ReplicatedMergeTree
         if (supportsReplication())

src/Storages/SelectQueryInfo.h

@@ -255,6 +255,8 @@ struct SelectQueryInfo
     Block minmax_count_projection_block;
     MergeTreeDataSelectAnalysisResultPtr merge_tree_select_result_ptr;
 
+    bool parallel_replicas_disabled = false;
+
     bool is_parameterized_view = false;
     NameToNameMap parameterized_view_values;
 

src/Storages/StorageMergeTree.cpp

@@ -209,7 +209,9 @@ void StorageMergeTree::read(
     size_t max_block_size,
     size_t num_streams)
 {
-    if (local_context->canUseParallelReplicasOnInitiator() && local_context->getSettingsRef().parallel_replicas_for_non_replicated_merge_tree)
+    if (!query_info.parallel_replicas_disabled &&
+        local_context->canUseParallelReplicasOnInitiator() &&
+        local_context->getSettingsRef().parallel_replicas_for_non_replicated_merge_tree)
     {
         auto table_id = getStorageID();
 
@@ -240,7 +242,10 @@ void StorageMergeTree::read(
     }
     else
     {
-        const bool enable_parallel_reading = local_context->canUseParallelReplicasOnFollower() && local_context->getSettingsRef().parallel_replicas_for_non_replicated_merge_tree;
+        const bool enable_parallel_reading =
+            !query_info.parallel_replicas_disabled &&
+            local_context->canUseParallelReplicasOnFollower() &&
+            local_context->getSettingsRef().parallel_replicas_for_non_replicated_merge_tree;
 
         if (auto plan = reader.read(
             column_names, storage_snapshot, query_info,
@@ -929,14 +934,20 @@ MergeMutateSelectedEntryPtr StorageMergeTree::selectPartsToMerge(
 
     SelectPartsDecision select_decision = SelectPartsDecision::CANNOT_SELECT;
 
-    if (!canEnqueueBackgroundTask())
+    auto is_background_memory_usage_ok = [](String * disable_reason) -> bool
     {
-        if (out_disable_reason)
-            *out_disable_reason = fmt::format("Current background tasks memory usage ({}) is more than the limit ({})",
+        if (canEnqueueBackgroundTask())
+            return true;
+        if (disable_reason)
+            *disable_reason = fmt::format("Current background tasks memory usage ({}) is more than the limit ({})",
                 formatReadableSizeWithBinarySuffix(background_memory_tracker.get()),
                 formatReadableSizeWithBinarySuffix(background_memory_tracker.getSoftLimit()));
-    }
-    else if (partition_id.empty())
+        return false;
+    };
+
+    if (partition_id.empty())
+    {
+        if (is_background_memory_usage_ok(out_disable_reason))
         {
             UInt64 max_source_parts_size = merger_mutator.getMaxSourcePartsSizeForMerge();
             bool merge_with_ttl_allowed = getTotalMergesWithTTLInMergeList() < data_settings->max_number_of_merges_with_ttl_in_pool;
@@ -958,15 +969,35 @@ MergeMutateSelectedEntryPtr StorageMergeTree::selectPartsToMerge(
             else if (out_disable_reason)
                 *out_disable_reason = "Current value of max_source_parts_size is zero";
         }
+    }
     else
     {
         while (true)
         {
-            select_decision = merger_mutator.selectAllPartsToMergeWithinPartition(
-                future_part, can_merge, partition_id, final, metadata_snapshot, txn, out_disable_reason, optimize_skip_merged_partitions);
             auto timeout_ms = getSettings()->lock_acquire_timeout_for_background_operations.totalMilliseconds();
             auto timeout = std::chrono::milliseconds(timeout_ms);
 
+            if (!is_background_memory_usage_ok(out_disable_reason))
+            {
+                constexpr auto poll_interval = std::chrono::seconds(1);
+                Int64 attempts = timeout / poll_interval;
+                bool ok = false;
+                for (Int64 i = 0; i < attempts; ++i)
+                {
+                    std::this_thread::sleep_for(poll_interval);
+                    if (is_background_memory_usage_ok(out_disable_reason))
+                    {
+                        ok = true;
+                        break;
+                    }
+                }
+                if (!ok)
+                    break;
+            }
+
+            select_decision = merger_mutator.selectAllPartsToMergeWithinPartition(
+                future_part, can_merge, partition_id, final, metadata_snapshot, txn, out_disable_reason, optimize_skip_merged_partitions);
+
             /// If final - we will wait for currently processing merges to finish and continue.
             if (final
                 && select_decision != SelectPartsDecision::SELECTED

tests/analyzer_tech_debt.txt

@@ -36,6 +36,7 @@
 01455_shard_leaf_max_rows_bytes_to_read
 01495_subqueries_in_with_statement
 01504_rocksdb
+01526_client_start_and_exit
 01527_dist_sharding_key_dictGet_reload
 01528_allow_nondeterministic_optimize_skip_unused_shards
 01540_verbatim_partition_pruning
@@ -50,6 +51,7 @@
 01624_soft_constraints
 01651_bugs_from_15889
 01656_test_query_log_factories_info
+01676_clickhouse_client_autocomplete
 01681_bloom_filter_nullable_column
 01700_system_zookeeper_path_in
 01710_projection_additional_filters

tests/ci/stress_tests.lib

@@ -243,7 +243,7 @@ function check_logs_for_critical_errors()
     # Remove file fatal_messages.txt if it's empty
     [ -s /test_output/fatal_messages.txt ] || rm /test_output/fatal_messages.txt
 
-    rg -Fa "########################################" /test_output/* > /dev/null \
+    rg -Faz "########################################" /test_output/* > /dev/null \
       && echo -e "Killed by signal (output files)$FAIL" >> /test_output/test_results.tsv
 
     function get_gdb_log_context()

tests/config/config.d/named_collection.xml

@@ -32,5 +32,10 @@
             <secret_access_key>testtest</secret_access_key>
             <structure>auto</structure>
         </s3_conn>
+        <s3_conn_db>
+            <url>http://localhost:11111/test/</url>
+            <access_key_id>test</access_key_id>
+            <secret_access_key>testtest</secret_access_key>
+        </s3_conn_db>
     </named_collections>
 </clickhouse>

tests/integration/test_storage_kerberized_hdfs/hdfs_configs/bootstrap.sh

@@ -111,6 +111,23 @@ cat > /usr/local/hadoop/etc/hadoop/hdfs-site.xml << EOF
   <name>dfs.datanode.http.address</name>
   <value>0.0.0.0:1006</value>
 </property>
+<!-- If the port is 0 then the server will start on a free port. -->
+<property>
+  <name>dfs.datanode.ipc.address</name>
+  <value>0.0.0.0:0</value>
+</property>
+<property>
+  <name>dfs.namenode.secondary.http-address</name>
+  <value>0.0.0.0:0</value>
+</property>
+<property>
+  <name>dfs.namenode.backup.address</name>
+  <value>0.0.0.0:0</value>
+</property>
+<property>
+  <name>dfs.namenode.backup.http-address</name>
+  <value>0.0.0.0:0</value>
+</property>
 <!--
 <property>
   <name>dfs.http.policy</name>

tests/queries/0_stateless/00474_readonly_settings.sh

@@ -1,6 +1,5 @@
 #!/usr/bin/env bash
-
-unset CLICKHOUSE_LOG_COMMENT
+# Tags: no-parallel
 
 CURDIR=$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)
 # shellcheck source=../shell_config.sh
@@ -12,12 +11,8 @@ $CLICKHOUSE_CLIENT --query="select toUInt64(pow(2, 62)) as value format JSON" --
 $CLICKHOUSE_CLIENT --readonly=1 --multiquery --query="set output_format_json_quote_64bit_integers=1 ; select toUInt64(pow(2, 63)) as value format JSON" --server_logs_file=/dev/null 2>&1 | grep -o -q 'value\|Cannot modify .* setting in readonly mode' && echo "OK" || echo "FAIL"
 $CLICKHOUSE_CLIENT --readonly=1 --multiquery --query="set output_format_json_quote_64bit_integers=0 ; select toUInt64(pow(2, 63)) as value format JSON" --server_logs_file=/dev/null 2>&1 | grep -o -q 'value\|Cannot modify .* setting in readonly mode' && echo "OK" || echo "FAIL"
 
-
 ${CLICKHOUSE_CURL} -sS "${CLICKHOUSE_URL}&query=SELECT+toUInt64(pow(2,+63))+as+value+format+JSON&output_format_json_quote_64bit_integers=1" | grep value
 ${CLICKHOUSE_CURL} -sS "${CLICKHOUSE_URL}&query=SELECT+toUInt64(pow(2,+63))+as+value+format+JSON&output_format_json_quote_64bit_integers=0" | grep value
 
-#${CLICKHOUSE_CURL} -sS "${CLICKHOUSE_URL}&session_id=readonly&session_timeout=3600" -d 'SET readonly = 1'
-
-${CLICKHOUSE_CURL} -sS "${CLICKHOUSE_URL}&session_id=readonly&query=SELECT+toUInt64(pow(2,+63))+as+value+format+JSON&output_format_json_quote_64bit_integers=1" 2>&1 | grep -o -q 'value\|Cannot modify .* setting in readonly mode.' && echo "OK" || echo "FAIL"
+${CLICKHOUSE_CURL} -sS "${CLICKHOUSE_URL}&session_id=readonly&query=SELECT+toUInt64(pow(2,+63))+as+value+format+JSON&output_format_json_quote_64bit_integers=1" 2>&1 | grep -o -q 'value\|Cannot modify .* setting in readonly mode' && echo "OK" || echo "FAIL"
 ${CLICKHOUSE_CURL} -sS "${CLICKHOUSE_URL}&session_id=readonly&query=SELECT+toUInt64(pow(2,+63))+as+value+format+JSON&output_format_json_quote_64bit_integers=0" 2>&1 | grep -o -q 'value\|Cannot modify .* setting in readonly mode' && echo "OK" || echo "FAIL"
-

tests/queries/0_stateless/01455_opentelemetry_distributed.sh

@@ -3,8 +3,6 @@
 
 set -ue
 
-unset CLICKHOUSE_LOG_COMMENT
-
 CURDIR=$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)
 # shellcheck source=../shell_config.sh
 . "$CURDIR"/../shell_config.sh

tests/queries/0_stateless/01526_initial_query_id.sh

@@ -1,8 +1,6 @@
 #!/usr/bin/env bash
 set -ue
 
-unset CLICKHOUSE_LOG_COMMENT
-
 CURDIR=$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)
 # shellcheck source=../shell_config.sh
 . "$CURDIR"/../shell_config.sh

tests/queries/0_stateless/01732_race_condition_storage_join_long.sh

@@ -1,8 +1,6 @@
 #!/usr/bin/env bash
 # Tags: race
 
-unset CLICKHOUSE_LOG_COMMENT
-
 CURDIR=$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)
 # shellcheck source=../shell_config.sh
 . "$CURDIR"/../shell_config.sh

tests/queries/0_stateless/01872_initial_query_start_time.sh

@@ -3,8 +3,6 @@ set -ue
 
 # this test doesn't need 'current_database = currentDatabase()',
 
-unset CLICKHOUSE_LOG_COMMENT
-
 CURDIR=$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)
 # shellcheck source=../shell_config.sh
 . "$CURDIR"/../shell_config.sh

tests/queries/0_stateless/02030_rocksdb_race_long.sh

@@ -1,8 +1,6 @@
 #!/usr/bin/env bash
 # Tags: race
 
-unset CLICKHOUSE_LOG_COMMENT
-
 CURDIR=$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)
 # shellcheck source=../shell_config.sh
 . "$CURDIR"/../shell_config.sh

tests/queries/0_stateless/02151_hash_table_sizes_stats.sh

@@ -3,8 +3,6 @@
 
 # shellcheck disable=SC2154
 
-unset CLICKHOUSE_LOG_COMMENT
-
 CURDIR=$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)
 # shellcheck source=../shell_config.sh
 . "$CURDIR"/../shell_config.sh

tests/queries/0_stateless/02151_hash_table_sizes_stats_distributed.sh

@@ -5,8 +5,6 @@
 
 # shellcheck disable=SC2154
 
-unset CLICKHOUSE_LOG_COMMENT
-
 CURDIR=$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)
 # shellcheck source=../shell_config.sh
 . "$CURDIR"/../shell_config.sh

tests/queries/0_stateless/02377_extend_protocol_with_query_parameters.sh

@@ -2,8 +2,6 @@
 
 # shellcheck disable=SC2154
 
-unset CLICKHOUSE_LOG_COMMENT
-
 CURDIR=$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)
 # shellcheck source=../shell_config.sh
 . "$CURDIR"/../shell_config.sh

tests/queries/0_stateless/02418_do_not_return_empty_blocks_from_ConvertingAggregatedToChunksTransform.sh

@@ -1,8 +1,6 @@
 #!/usr/bin/env bash
 set -ue
 
-unset CLICKHOUSE_LOG_COMMENT
-
 CURDIR=$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)
 # shellcheck source=../shell_config.sh
 . "$CURDIR"/../shell_config.sh

tests/queries/0_stateless/02473_functions_in_readonly_mode.sh

@@ -1,7 +1,5 @@
 #!/usr/bin/env bash
 
-unset CLICKHOUSE_LOG_COMMENT
-
 CURDIR=$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)
 # shellcheck source=../shell_config.sh
 . "$CURDIR"/../shell_config.sh

tests/queries/0_stateless/02499_monotonicity_toUnixTimestamp64.sh

@@ -3,8 +3,6 @@
 
 # shellcheck disable=SC2154
 
-unset CLICKHOUSE_LOG_COMMENT
-
 CURDIR=$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)
 # shellcheck source=../shell_config.sh
 . "$CURDIR"/../shell_config.sh

tests/queries/0_stateless/02581_share_big_sets_between_multiple_mutations_tasks_long.sql

@@ -1,4 +1,6 @@
--- Tags: long, no-debug, no-tsan, no-asan, no-ubsan, no-msan
+-- Tags: long, no-debug, no-tsan, no-asan, no-ubsan, no-msan, no-parallel
+
+-- no-parallel because the sets use a lot of memory, which may interfere with other tests
 
 DROP TABLE IF EXISTS 02581_trips;
 

tests/queries/0_stateless/02581_share_big_sets_between_mutation_tasks_long.sql

@@ -1,4 +1,6 @@
--- Tags: long, no-debug, no-tsan, no-asan, no-ubsan, no-msan
+-- Tags: long, no-debug, no-tsan, no-asan, no-ubsan, no-msan, no-parallel
+
+-- no-parallel because the sets use a lot of memory, which may interfere with other tests
 
 DROP TABLE IF EXISTS 02581_trips;
 

tests/queries/0_stateless/02681_final_excessive_reading_bug.sh

@@ -3,8 +3,6 @@
 
 # shellcheck disable=SC2154
 
-unset CLICKHOUSE_LOG_COMMENT
-
 CURDIR=$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)
 # shellcheck source=../shell_config.sh
 . "$CURDIR"/../shell_config.sh

tests/queries/0_stateless/02707_clickhouse_local_implicit_file_table_function.reference

@@ -0,0 +1,9 @@
+Test 1: check explicit and implicit call of the file table function
+explicit:
+4
+implicit:
+4
+Test 2: check Filesystem database
+4
+Test 3: check show database with Filesystem
+test02707

tests/queries/0_stateless/02707_clickhouse_local_implicit_file_table_function.sh

@@ -0,0 +1,45 @@
+#!/usr/bin/env bash
+
+CURDIR=$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)
+# shellcheck source=../shell_config.sh
+. "$CURDIR"/../shell_config.sh
+
+dir=${CLICKHOUSE_TEST_UNIQUE_NAME}
+[[ -d $dir ]] && rm -rd $dir
+mkdir $dir
+
+# Create temporary csv file for tests
+echo '"id","str","int","text"' > $dir/tmp.csv
+echo '1,"abc",123,"abacaba"' >> $dir/tmp.csv
+echo '2,"def",456,"bacabaa"' >> $dir/tmp.csv
+echo '3,"story",78912,"acabaab"' >> $dir/tmp.csv
+echo '4,"history",21321321,"cabaaba"' >> $dir/tmp.csv
+
+#################
+echo "Test 1: check explicit and implicit call of the file table function"
+
+echo "explicit:"
+$CLICKHOUSE_LOCAL -q "SELECT COUNT(*) FROM file('${dir}/tmp.csv')"
+echo "implicit:"
+$CLICKHOUSE_LOCAL -q "SELECT COUNT(*) FROM \"${dir}/tmp.csv\""
+
+#################
+echo "Test 2: check Filesystem database"
+$CLICKHOUSE_LOCAL --multiline --multiquery -q """
+DROP DATABASE IF EXISTS test;
+CREATE DATABASE test ENGINE = Filesystem('${dir}');
+SELECT COUNT(*) FROM test.\`tmp.csv\`;
+DROP DATABASE test;
+"""
+
+#################
+echo "Test 3: check show database with Filesystem"
+$CLICKHOUSE_LOCAL --multiline --multiquery -q """
+DROP DATABASE IF EXISTS test02707;
+CREATE DATABASE test02707 ENGINE = Filesystem('${dir}');
+SHOW DATABASES;
+DROP DATABASE test02707;
+""" | grep "test02707"
+
+# Remove temporary dir with files
+rm -rd $dir

tests/queries/0_stateless/02722_database_filesystem.reference

@@ -0,0 +1,15 @@
+Test 1: create filesystem database and check implicit calls
+0
+test1
+4
+4
+4
+Test 2: check DatabaseFilesystem access rights and errors handling on server
+OK
+OK
+OK
+OK
+OK
+OK
+OK
+OK

tests/queries/0_stateless/02722_database_filesystem.sh

@@ -0,0 +1,72 @@
+#!/usr/bin/env bash
+# Tags: no-parallel
+
+CURDIR=$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)
+# shellcheck source=../shell_config.sh
+. "$CURDIR"/../shell_config.sh
+
+# see 01658_read_file_to_stringcolumn.sh
+CLICKHOUSE_USER_FILES_PATH=$(clickhouse-client --query "select _path, _file from file('nonexist.txt', 'CSV', 'val1 char')" 2>&1 | grep Exception | awk '{gsub("/nonexist.txt","",$9); print $9}')
+
+# Prepare data
+unique_name=${CLICKHOUSE_TEST_UNIQUE_NAME}
+user_files_tmp_dir=${CLICKHOUSE_USER_FILES_PATH}/${unique_name}
+mkdir -p ${user_files_tmp_dir}/tmp/
+echo '"id","str","int","text"' > ${user_files_tmp_dir}/tmp.csv
+echo '1,"abc",123,"abacaba"' >> ${user_files_tmp_dir}/tmp.csv
+echo '2,"def",456,"bacabaa"' >> ${user_files_tmp_dir}/tmp.csv
+echo '3,"story",78912,"acabaab"' >> ${user_files_tmp_dir}/tmp.csv
+echo '4,"history",21321321,"cabaaba"' >> ${user_files_tmp_dir}/tmp.csv
+
+tmp_dir=${CLICKHOUSE_TEST_UNIQUE_NAME}
+[[ -d $tmp_dir ]] && rm -rd $tmp_dir
+mkdir $tmp_dir
+cp ${user_files_tmp_dir}/tmp.csv ${tmp_dir}/tmp.csv
+cp ${user_files_tmp_dir}/tmp.csv ${user_files_tmp_dir}/tmp/tmp.csv
+cp ${user_files_tmp_dir}/tmp.csv ${user_files_tmp_dir}/tmp.myext
+
+#################
+echo "Test 1: create filesystem database and check implicit calls"
+${CLICKHOUSE_CLIENT} --multiline --multiquery -q """
+DROP DATABASE IF EXISTS test1;
+CREATE DATABASE test1 ENGINE = Filesystem;
+"""
+echo $?
+${CLICKHOUSE_CLIENT} --query "SHOW DATABASES" | grep "test1"
+${CLICKHOUSE_CLIENT} --query "SELECT COUNT(*) FROM test1.\`${unique_name}/tmp.csv\`;"
+${CLICKHOUSE_CLIENT} --query "SELECT COUNT(*) FROM test1.\`${unique_name}/tmp/tmp.csv\`;"
+${CLICKHOUSE_LOCAL} -q "SELECT COUNT(*) FROM \"${tmp_dir}/tmp.csv\""
+
+#################
+echo "Test 2: check DatabaseFilesystem access rights and errors handling on server"
+# DATABASE_ACCESS_DENIED: Allows list files only inside user_files
+${CLICKHOUSE_CLIENT} --query "SELECT COUNT(*) FROM test1.\`../tmp.csv\`;" 2>&1| grep -F "Code: 481" > /dev/null && echo "OK" || echo 'FAIL' ||:
+${CLICKHOUSE_CLIENT} --query "SELECT COUNT(*) FROM test1.\`/tmp/tmp.csv\`;" 2>&1| grep -F "Code: 481" > /dev/null && echo "OK" || echo 'FAIL' ||:
+${CLICKHOUSE_CLIENT} --multiline --multiquery --query """
+USE test1;
+SELECT COUNT(*) FROM \"../${tmp_dir}/tmp.csv\";
+""" 2>&1| grep -F "Code: 481" > /dev/null && echo "OK" || echo 'FAIL' ||:
+${CLICKHOUSE_CLIENT} --query "SELECT COUNT(*) FROM test1.\`../../../../../../tmp.csv\`;" 2>&1| grep -F "Code: 481" > /dev/null && echo "OK" || echo 'FAIL' ||:
+
+# BAD_ARGUMENTS: path should be inside user_files
+${CLICKHOUSE_CLIENT} --multiline --multiquery -q """
+DROP DATABASE IF EXISTS test2;
+CREATE DATABASE test2 ENGINE = Filesystem('/tmp');
+""" 2>&1| grep -F "Code: 36" > /dev/null && echo "OK" || echo 'FAIL' ||:
+
+# BAD_ARGUMENTS: .../user_files/relative_unknown_dir does not exists
+${CLICKHOUSE_CLIENT} --multiline --multiquery -q """
+DROP DATABASE IF EXISTS test2;
+CREATE DATABASE test2 ENGINE = Filesystem('relative_unknown_dir');
+""" 2>&1| grep -F "Code: 36" > /dev/null && echo "OK" || echo 'FAIL' ||:
+
+# FILE_DOESNT_EXIST: unknown file
+${CLICKHOUSE_CLIENT} --query "SELECT COUNT(*) FROM test1.\`tmp2.csv\`;" 2>&1| grep -F "Code: 60" > /dev/null && echo "OK" || echo 'FAIL' ||:
+
+# BAD_ARGUMENTS: Cannot determine the file format by it's extension
+${CLICKHOUSE_CLIENT} --query "SELECT COUNT(*) FROM test1.\`${unique_name}/tmp.myext\`;" 2>&1| grep -F "Code: 36" > /dev/null && echo "OK" || echo 'FAIL' ||:
+
+# Clean
+${CLICKHOUSE_CLIENT} --query "DROP DATABASE test1;"
+rm -rd $tmp_dir
+rm -rd $user_files_tmp_dir

tests/queries/0_stateless/02724_database_s3.reference

@@ -0,0 +1,21 @@
+Test 1: select from s3
+1	2	3
+4	5	6
+7	8	9
+0	0	0
+test1
+10	11	12
+13	14	15
+16	17	18
+0	0	0
+10	11	12
+13	14	15
+16	17	18
+0	0	0
+10	11	12
+13	14	15
+16	17	18
+0	0	0
+Test 2: check exceptions
+OK
+OK

tests/queries/0_stateless/02724_database_s3.sh

@@ -0,0 +1,63 @@
+#!/usr/bin/env bash
+# Tags: no-fasttest, no-parallel
+# Tag no-fasttest: Depends on AWS
+
+CUR_DIR=$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)
+# shellcheck source=../shell_config.sh
+. "$CUR_DIR"/../shell_config.sh
+
+#################
+echo "Test 1: select from s3"
+${CLICKHOUSE_CLIENT} --multiline --multiquery -q """
+DROP DATABASE IF EXISTS test1;
+CREATE DATABASE test1 ENGINE = S3;
+USE test1;
+SELECT * FROM \"http://localhost:11111/test/a.tsv\"
+"""
+${CLICKHOUSE_CLIENT} -q "SHOW DATABASES;" | grep test1
+
+# check credentials with absolute path
+${CLICKHOUSE_CLIENT} --multiline --multiquery -q """
+DROP DATABASE IF EXISTS test2;
+CREATE DATABASE test2 ENGINE = S3('', 'test', 'testtest');
+USE test2;
+SELECT * FROM \"http://localhost:11111/test/b.tsv\"
+"""
+
+# check credentials with relative path
+${CLICKHOUSE_CLIENT} --multiline --multiquery -q """
+DROP DATABASE IF EXISTS test4;
+CREATE DATABASE test4 ENGINE = S3('http://localhost:11111/test', 'test', 'testtest');
+USE test4;
+SELECT * FROM \"b.tsv\"
+"""
+
+# Check named collection loading
+${CLICKHOUSE_CLIENT} --multiline --multiquery -q """
+DROP DATABASE IF EXISTS test5;
+CREATE DATABASE test5 ENGINE = S3(s3_conn_db);
+SELECT * FROM test5.\`b.tsv\`
+"""
+
+#################
+echo "Test 2: check exceptions"
+${CLICKHOUSE_CLIENT} --multiline --multiquery -q """
+DROP DATABASE IF EXISTS test3;
+CREATE DATABASE test3 ENGINE = S3;
+USE test3;
+SELECT * FROM \"http://localhost:11111/test/a.myext\"
+""" 2>&1| grep -F "UNKNOWN_TABLE" > /dev/null && echo "OK"
+
+${CLICKHOUSE_CLIENT} --multiline --multiquery -q """
+USE test3;
+SELECT * FROM \"abacaba\"
+""" 2>&1| grep -F "UNKNOWN_TABLE" > /dev/null && echo "OK"
+
+# Cleanup
+${CLICKHOUSE_CLIENT} --multiline --multiquery -q """
+DROP DATABASE IF EXISTS test1;
+DROP DATABASE IF EXISTS test2;
+DROP DATABASE IF EXISTS test3;
+DROP DATABASE IF EXISTS test4;
+DROP DATABASE IF EXISTS test5;
+"""

tests/queries/0_stateless/02725_database_hdfs.reference

@@ -0,0 +1,12 @@
+Test 1: select from hdfs database
+1	2	3
+test1
+1	2	3
+test2
+Test 2: check exceptions
+OK0
+OK1
+OK2
+OK3
+OK4
+OK5

tests/queries/0_stateless/02725_database_hdfs.sh

@@ -0,0 +1,60 @@
+#!/usr/bin/env bash
+# Tags: no-fasttest, use-hdfs, no-parallel
+
+CURDIR=$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)
+# shellcheck source=../shell_config.sh
+. "$CURDIR"/../shell_config.sh
+
+# Prepare data
+${CLICKHOUSE_CLIENT} -q "insert into table function hdfs('hdfs://localhost:12222/test_02725_1.tsv', 'TSV', 'column1 UInt32, column2 UInt32, column3 UInt32') select 1, 2, 3 settings hdfs_truncate_on_insert=1;"
+${CLICKHOUSE_CLIENT} -q "insert into table function hdfs('hdfs://localhost:12222/test_02725_2.tsv', 'TSV', 'column1 UInt32, column2 UInt32, column3 UInt32') select 4, 5, 6 settings hdfs_truncate_on_insert=1;"
+
+#################
+echo "Test 1: select from hdfs database"
+
+# Database without specific host
+${CLICKHOUSE_CLIENT} --multiline --multiquery -q """
+DROP DATABASE IF EXISTS test1;
+CREATE DATABASE test1 ENGINE = HDFS;
+USE test1;
+SELECT * FROM \"hdfs://localhost:12222/test_02725_1.tsv\"
+"""
+${CLICKHOUSE_CLIENT} -q "SHOW DATABASES;" | grep test1
+
+# Database with host
+${CLICKHOUSE_CLIENT} --multiline --multiquery -q """
+DROP DATABASE IF EXISTS test2;
+CREATE DATABASE test2 ENGINE = HDFS('hdfs://localhost:12222');
+USE test2;
+SELECT * FROM \"test_02725_1.tsv\"
+"""
+${CLICKHOUSE_CLIENT} -q "SHOW DATABASES;" | grep test2
+
+#################
+echo "Test 2: check exceptions"
+
+${CLICKHOUSE_CLIENT} --multiline --multiquery -q """
+DROP DATABASE IF EXISTS test3;
+CREATE DATABASE test3 ENGINE = HDFS('abacaba');
+""" 2>&1| grep -F "BAD_ARGUMENTS" > /dev/null && echo "OK0"
+
+${CLICKHOUSE_CLIENT} --multiline --multiquery -q """
+DROP DATABASE IF EXISTS test4;
+CREATE DATABASE test4 ENGINE = HDFS;
+USE test4;
+SELECT * FROM \"abacaba/file.tsv\"
+""" 2>&1| grep -F "UNKNOWN_TABLE" > /dev/null && echo "OK1"
+
+${CLICKHOUSE_CLIENT} -q "SELECT * FROM test4.\`http://localhost:11111/test/a.tsv\`" 2>&1| grep -F "UNKNOWN_TABLE" > /dev/null && echo "OK2"
+${CLICKHOUSE_CLIENT} --query "SELECT * FROM test4.\`hdfs://localhost:12222/file.myext\`" 2>&1| grep -F "UNKNOWN_TABLE" > /dev/null && echo "OK3"
+${CLICKHOUSE_CLIENT} --query "SELECT * FROM test4.\`hdfs://localhost:12222/test_02725_3.tsv\`" 2>&1| grep -F "UNKNOWN_TABLE" > /dev/null && echo "OK4"
+${CLICKHOUSE_CLIENT} --query "SELECT * FROM test4.\`hdfs://localhost:12222\`" 2>&1| grep -F "UNKNOWN_TABLE" > /dev/null && echo "OK5"
+
+
+# Cleanup
+${CLICKHOUSE_CLIENT} --multiline --multiquery -q """
+DROP DATABASE IF EXISTS test1;
+DROP DATABASE IF EXISTS test2;
+DROP DATABASE IF EXISTS test3;
+DROP DATABASE IF EXISTS test4;
+"""

tests/queries/0_stateless/02811_parallel_replicas_prewhere_count.reference

@@ -0,0 +1,4 @@
+-- count() ------------------------------
+2
+-- count() with parallel replicas -------
+2

tests/queries/0_stateless/02811_parallel_replicas_prewhere_count.sql

@@ -0,0 +1,24 @@
+DROP TABLE IF EXISTS users;
+CREATE TABLE users (uid Int16, name String, age Int16) ENGINE=MergeTree() ORDER BY uid;
+
+INSERT INTO users VALUES (111, 'JFK', 33);
+INSERT INTO users VALUES (6666, 'KLM', 48);
+INSERT INTO users VALUES (88888, 'AMS', 50);
+
+SELECT '-- count() ------------------------------';
+SELECT count() FROM users PREWHERE uid > 2000;
+
+-- enable parallel replicas but with high granules threshold
+SET
+skip_unavailable_shards=1,
+allow_experimental_parallel_reading_from_replicas=1,
+max_parallel_replicas=3,
+use_hedged_requests=0,
+cluster_for_parallel_replicas='parallel_replicas',
+parallel_replicas_for_non_replicated_merge_tree=1,
+parallel_replicas_min_number_of_granules_to_enable=1000;
+
+SELECT '-- count() with parallel replicas -------';
+SELECT count() FROM users PREWHERE uid > 2000;
+
+DROP TABLE users;

tests/queries/1_stateful/00177_memory_bound_merging.sh

@@ -2,8 +2,6 @@
 
 # shellcheck disable=SC2154
 
-unset CLICKHOUSE_LOG_COMMENT
-
 CURDIR=$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)
 # shellcheck source=../shell_config.sh
 . "$CURDIR"/../shell_config.sh