Merge remote-tracking branch 'origin/master' into yandex-to-clickhouse-in-configs

docs/tools/requirements.txt

@@ -22,7 +22,7 @@ mkdocs-macros-plugin==0.4.20
 nltk==3.5
 nose==1.3.7
 protobuf==3.14.0
-numpy==1.19.2
+numpy==1.21.2
 pymdown-extensions==8.0
 python-slugify==4.0.1
 PyYAML==5.4.1

docs/zh/sql-reference/aggregate-functions/parametric-functions.md

@@ -230,22 +230,24 @@ SELECT sequenceCount('(?1).*(?2)')(time, number = 1, number = 2) FROM t
 
 -   该函数搜索触发链中的第一个条件并将事件计数器设置为1。 这是滑动窗口启动的时刻。
 
--   如果来自链的事件在窗口内顺序发生，则计数器将递增。 如果事件序列中断，则计数器不会增加。
+-   如果来自链的事件在窗口内顺序发生，则计数器将递增。 如果事件序列中断，则计数器不再增加。
 
 -   如果数据在不同的完成点具有多个事件链，则该函数将仅输出最长链的大小。
 
 **语法**
 
 ``` sql
-windowFunnel(window, [mode])(timestamp, cond1, cond2, ..., condN)
+windowFunnel(window, [mode, [mode, ... ]])(timestamp, cond1, cond2, ..., condN)
 ```
 
 **参数**
 
--   `window` — 滑动窗户的大小，单位是秒。
+-   `window` — 滑动窗户的大小，表示事件链中第一个事件和最后一个事件的最大间隔。 单位取决于`timestamp `。用表达式来表示则是：`timestamp of cond1 <= timestamp of cond2 <= ... <= timestamp of condN <= timestamp of cond1 + window`。
--   `mode` - 这是一个可选的参数。
+-   `mode` - 这是一个可选的参数，可以设置一个或多个参数。
-    -   `'strict'` - 当 `'strict'` 设置时，windowFunnel()仅对唯一值应用匹配条件。
+    -   `'strict_deduplication'` - 如果事件链中出现相同的条件，则会停止进一步搜索。
--   `timestamp` — 包含时间的列。 数据类型支持： [日期](../../sql-reference/data-types/date.md), [日期时间](../../sql-reference/data-types/datetime.md#data_type-datetime) 和其他无符号整数类型（请注意，即使时间戳支持 `UInt64` 类型，它的值不能超过Int64最大值，即2^63-1）。
+    -   `'strict_order'` - 不允许其他事件的介入。 例如：在`A->B->D->C`的情况下，它在`D`停止继续搜索`A->B->C`，最大事件数为2。
+    -   `'strict_increase'` - 事件链中的时间戳必须严格上升。
+-   `timestamp` — 包含时间戳的列。 数据类型支持： [日期](../../sql-reference/data-types/date.md), [日期时间](../../sql-reference/data-types/datetime.md#data_type-datetime) 和其他无符号整数类型（请注意，即使时间戳支持 `UInt64` 类型，它的值也不能超过Int64最大值，即2^63-1）。
 -   `cond` — 事件链的约束条件。 [UInt8](../../sql-reference/data-types/int-uint.md) 类型。
 
 **返回值**

src/Common/filesystemHelpers.cpp

@@ -113,13 +113,9 @@ String getFilesystemName([[maybe_unused]] const String & mount_point)
 
 bool pathStartsWith(const std::filesystem::path & path, const std::filesystem::path & prefix_path)
 {
-    auto absolute_path = std::filesystem::weakly_canonical(path);
+    String absolute_path = std::filesystem::weakly_canonical(path);
-    auto absolute_prefix_path = std::filesystem::weakly_canonical(prefix_path);
+    String absolute_prefix_path = std::filesystem::weakly_canonical(prefix_path);
-
+    return absolute_path.starts_with(absolute_prefix_path);
-    auto [_, prefix_path_mismatch_it] = std::mismatch(absolute_path.begin(), absolute_path.end(), absolute_prefix_path.begin(), absolute_prefix_path.end());
-
-    bool path_starts_with_prefix_path = (prefix_path_mismatch_it == absolute_prefix_path.end());
-    return path_starts_with_prefix_path;
 }
 
 bool symlinkStartsWith(const std::filesystem::path & path, const std::filesystem::path & prefix_path)
@@ -129,15 +125,11 @@ bool symlinkStartsWith(const std::filesystem::path & path, const std::filesystem
     /// `.` and `..` and extra `/`. Path is not canonized because otherwise path will
     /// not be a path of a symlink itself.
 
-    auto absolute_path = std::filesystem::absolute(path);
+    String absolute_path = std::filesystem::absolute(path);
-    absolute_path = absolute_path.lexically_normal(); /// Normalize path.
+    absolute_path = fs::path(absolute_path).lexically_normal(); /// Normalize path.
-    auto absolute_prefix_path = std::filesystem::absolute(prefix_path);
+    String absolute_prefix_path = std::filesystem::absolute(prefix_path);
-    absolute_prefix_path = absolute_prefix_path.lexically_normal(); /// Normalize path.
+    absolute_prefix_path = fs::path(absolute_prefix_path).lexically_normal(); /// Normalize path.
-
+    return absolute_path.starts_with(absolute_prefix_path);
-    auto [_, prefix_path_mismatch_it] = std::mismatch(absolute_path.begin(), absolute_path.end(), absolute_prefix_path.begin(), absolute_prefix_path.end());
-
-    bool path_starts_with_prefix_path = (prefix_path_mismatch_it == absolute_prefix_path.end());
-    return path_starts_with_prefix_path;
 }
 
 bool pathStartsWith(const String & path, const String & prefix_path)

src/DataStreams/PushingToViewsBlockOutputStream.cpp

@@ -348,7 +348,7 @@ Chain buildPushingToViewsChain(
     /// Do not push to destination table if the flag is set
     else if (!no_destination)
     {
-        auto sink = storage->write(query_ptr, storage->getInMemoryMetadataPtr(), context);
+        auto sink = storage->write(query_ptr, metadata_snapshot, context);
         metadata_snapshot->check(sink->getHeader().getColumnsWithTypeAndName());
         sink->setRuntimeData(thread_status, elapsed_counter_ms);
         result_chain.addSource(std::move(sink));

src/Functions/FunctionCustomWeekToSomething.h

@@ -130,20 +130,17 @@ public:
 
     Monotonicity getMonotonicityForRange(const IDataType & type, const Field & left, const Field & right) const override
     {
-        IFunction::Monotonicity is_monotonic{true};
+        if constexpr (std::is_same_v<typename Transform::FactorTransform, ZeroTransform>)
-        IFunction::Monotonicity is_not_monotonic;
+            return { .is_monotonic = true, .is_always_monotonic = true };
 
-        if (std::is_same_v<typename Transform::FactorTransform, ZeroTransform>)
+        const IFunction::Monotonicity is_monotonic = { .is_monotonic = true };
-        {
+        const IFunction::Monotonicity is_not_monotonic;
-            is_monotonic.is_always_monotonic = true;
-            return is_monotonic;
-        }
 
         /// This method is called only if the function has one argument. Therefore, we do not care about the non-local time zone.
         const DateLUTImpl & date_lut = DateLUT::instance();
 
         if (left.isNull() || right.isNull())
-            return is_not_monotonic;
+            return {};
 
         /// The function is monotonous on the [left, right] segment, if the factor transformation returns the same values for them.
 

src/Functions/FunctionDateOrDateTimeToSomething.h

@@ -128,14 +128,11 @@ public:
 
     Monotonicity getMonotonicityForRange(const IDataType & type, const Field & left, const Field & right) const override
     {
-        IFunction::Monotonicity is_monotonic { true };
+        if constexpr (std::is_same_v<typename Transform::FactorTransform, ZeroTransform>)
-        IFunction::Monotonicity is_not_monotonic;
+            return { .is_monotonic = true, .is_always_monotonic = true };
 
-        if (std::is_same_v<typename Transform::FactorTransform, ZeroTransform>)
+        const IFunction::Monotonicity is_monotonic = { .is_monotonic = true };
-        {
+        const IFunction::Monotonicity is_not_monotonic;
-            is_monotonic.is_always_monotonic = true;
-            return is_monotonic;
-        }
 
         /// This method is called only if the function has one argument. Therefore, we do not care about the non-local time zone.
         const DateLUTImpl & date_lut = DateLUT::instance();

src/Functions/FunctionUnaryArithmetic.h

@@ -290,7 +290,7 @@ struct PositiveMonotonicity
     static bool has() { return true; }
     static IFunction::Monotonicity get(const Field &, const Field &)
     {
-        return { true };
+        return { .is_monotonic = true };
     }
 };
 

src/Functions/FunctionsConversion.h

@@ -1954,7 +1954,7 @@ struct PositiveMonotonicity
     static bool has() { return true; }
     static IFunction::Monotonicity get(const IDataType &, const Field &, const Field &)
     {
-        return { true };
+        return { .is_monotonic = true };
     }
 };
 
@@ -1963,7 +1963,7 @@ struct UnknownMonotonicity
     static bool has() { return false; }
     static IFunction::Monotonicity get(const IDataType &, const Field &, const Field &)
     {
-        return { false };
+        return { };
     }
 };
 
@@ -1989,13 +1989,13 @@ struct ToNumberMonotonicity
         /// (Enum has separate case, because it is different data type)
         if (checkAndGetDataType<DataTypeNumber<T>>(&type) ||
             checkAndGetDataType<DataTypeEnum<T>>(&type))
-            return { true, true, true };
+            return { .is_monotonic = true, .is_always_monotonic = true };
 
         /// Float cases.
 
         /// When converting to Float, the conversion is always monotonic.
-        if (std::is_floating_point_v<T>)
+        if constexpr (std::is_floating_point_v<T>)
-            return {true, true, true};
+            return { .is_monotonic = true, .is_always_monotonic = true };
 
         /// If converting from Float, for monotonicity, arguments must fit in range of result type.
         if (WhichDataType(type).isFloat())
@@ -2010,7 +2010,7 @@ struct ToNumberMonotonicity
                 && left_float <= static_cast<Float64>(std::numeric_limits<T>::max())
                 && right_float >= static_cast<Float64>(std::numeric_limits<T>::min())
                 && right_float <= static_cast<Float64>(std::numeric_limits<T>::max()))
-                return { true };
+                return { .is_monotonic = true };
 
             return {};
         }
@@ -2035,10 +2035,10 @@ struct ToNumberMonotonicity
         if (size_of_from == size_of_to)
         {
             if (from_is_unsigned == to_is_unsigned)
-                return {true, true, true};
+                return { .is_monotonic = true, .is_always_monotonic = true };
 
             if (left_in_first_half == right_in_first_half)
-                return {true};
+                return { .is_monotonic = true };
 
             return {};
         }
@@ -2047,14 +2047,14 @@ struct ToNumberMonotonicity
         if (size_of_from < size_of_to)
         {
             if (from_is_unsigned == to_is_unsigned)
-                return {true, true, true};
+                return { .is_monotonic = true, .is_always_monotonic = true };
 
             if (!to_is_unsigned)
-                return {true, true, true};
+                return { .is_monotonic = true, .is_always_monotonic = true };
 
             /// signed -> unsigned. If arguments from the same half, then function is monotonic.
             if (left_in_first_half == right_in_first_half)
-                return {true};
+                return { .is_monotonic = true };
 
             return {};
         }
@@ -2071,10 +2071,14 @@ struct ToNumberMonotonicity
                 return {};
 
             if (to_is_unsigned)
-                return {true};
+                return { .is_monotonic = true };
             else
+            {
                 // If To is signed, it's possible that the signedness is different after conversion. So we check it explicitly.
-                return {(T(left.get<UInt64>()) >= 0) == (T(right.get<UInt64>()) >= 0)};
+                const bool is_monotonic = (T(left.get<UInt64>()) >= 0) == (T(right.get<UInt64>()) >= 0);
+
+                return { .is_monotonic = is_monotonic };
+            }
         }
 
         __builtin_unreachable();
@@ -2089,7 +2093,7 @@ struct ToDateMonotonicity
     {
         auto which = WhichDataType(type);
         if (which.isDateOrDate32() || which.isDateTime() || which.isDateTime64() || which.isInt8() || which.isInt16() || which.isUInt8() || which.isUInt16())
-            return {true, true, true};
+            return { .is_monotonic = true, .is_always_monotonic = true };
         else if (
             (which.isUInt() && ((left.isNull() || left.get<UInt64>() < 0xFFFF) && (right.isNull() || right.get<UInt64>() >= 0xFFFF)))
             || (which.isInt() && ((left.isNull() || left.get<Int64>() < 0xFFFF) && (right.isNull() || right.get<Int64>() >= 0xFFFF)))
@@ -2097,7 +2101,7 @@ struct ToDateMonotonicity
             || !type.isValueRepresentedByNumber())
             return {};
         else
-            return {true, true, true};
+            return { .is_monotonic = true, .is_always_monotonic = true };
     }
 };
 
@@ -2108,7 +2112,7 @@ struct ToDateTimeMonotonicity
     static IFunction::Monotonicity get(const IDataType & type, const Field &, const Field &)
     {
         if (type.isValueRepresentedByNumber())
-            return {true, true, true};
+            return { .is_monotonic = true, .is_always_monotonic = true };
         else
             return {};
     }
@@ -2123,7 +2127,7 @@ struct ToStringMonotonicity
 
     static IFunction::Monotonicity get(const IDataType & type, const Field & left, const Field & right)
     {
-        IFunction::Monotonicity positive(true, true);
+        IFunction::Monotonicity positive{ .is_monotonic = true };
         IFunction::Monotonicity not_monotonic;
 
         const auto * type_ptr = &type;

src/Functions/FunctionsRound.h

@@ -614,7 +614,7 @@ public:
 
     Monotonicity getMonotonicityForRange(const IDataType &, const Field &, const Field &) const override
     {
-        return { true, true, true };
+        return { .is_monotonic = true, .is_always_monotonic = true };
     }
 };
 

src/Functions/IFunction.h

@@ -250,12 +250,9 @@ public:
     /// The property of monotonicity for a certain range.
     struct Monotonicity
     {
-        bool is_monotonic = false;    /// Is the function monotonous (nondecreasing or nonincreasing).
+        bool is_monotonic = false;    /// Is the function monotonous (non-decreasing or non-increasing).
-        bool is_positive = true;    /// true if the function is nondecreasing, false, if notincreasing. If is_monotonic = false, then it does not matter.
+        bool is_positive = true;    /// true if the function is non-decreasing, false if non-increasing. If is_monotonic = false, then it does not matter.
         bool is_always_monotonic = false; /// Is true if function is monotonic on the whole input range I
-
-        Monotonicity(bool is_monotonic_ = false, bool is_positive_ = true, bool is_always_monotonic_ = false)
-                : is_monotonic(is_monotonic_), is_positive(is_positive_), is_always_monotonic(is_always_monotonic_) {}
     };
 
     /** Get information about monotonicity on a range of values. Call only if hasInformationAboutMonotonicity.

src/Functions/abs.cpp

@@ -46,7 +46,7 @@ template <> struct FunctionUnaryArithmeticMonotonicity<NameAbs>
         if ((left_float < 0 && right_float > 0) || (left_float > 0 && right_float < 0))
             return {};
 
-        return { true, (left_float > 0) };
+        return { .is_monotonic = true, .is_positive = left_float > 0 };
     }
 };
 

src/Functions/date_trunc.cpp

@@ -143,7 +143,7 @@ public:
 
     Monotonicity getMonotonicityForRange(const IDataType &, const Field &, const Field &) const override
     {
-        return { true, true, true };
+        return { .is_monotonic = true, .is_always_monotonic = true };
     }
 
 private:

src/Functions/fromModifiedJulianDay.cpp

@@ -139,10 +139,7 @@ namespace DB
 
         Monotonicity getMonotonicityForRange(const IDataType &, const Field &, const Field &) const override
         {
-            return Monotonicity(
+            return { .is_monotonic = true, .is_always_monotonic = true };
-                true,  // is_monotonic
-                true,  // is_positive
-                true); // is_always_monotonic
         }
 
     private:

src/Functions/intExp10.cpp

@@ -55,7 +55,7 @@ template <> struct FunctionUnaryArithmeticMonotonicity<NameIntExp10>
         if (left_float < 0 || right_float > 19)
             return {};
 
-        return { true };
+        return { .is_monotonic = true };
     }
 };
 

src/Functions/intExp2.cpp

@@ -58,7 +58,7 @@ template <> struct FunctionUnaryArithmeticMonotonicity<NameIntExp2>
         if (left_float < 0 || right_float > 63)
             return {};
 
-        return { true };
+        return { .is_monotonic = true };
     }
 };
 

src/Functions/negate.cpp

@@ -42,7 +42,7 @@ template <> struct FunctionUnaryArithmeticMonotonicity<NameNegate>
     static bool has() { return true; }
     static IFunction::Monotonicity get(const Field &, const Field &)
     {
-        return { true, false };
+        return { .is_monotonic = true, .is_positive = false };
     }
 };
 

src/Functions/sign.cpp

@@ -37,7 +37,10 @@ template <>
 struct FunctionUnaryArithmeticMonotonicity<NameSign>
 {
     static bool has() { return true; }
-    static IFunction::Monotonicity get(const Field &, const Field &) { return {true, true, false}; }
+    static IFunction::Monotonicity get(const Field &, const Field &)
+    {
+        return { .is_monotonic = true };
+    }
 };
 
 void registerFunctionSign(FunctionFactory & factory)

src/Functions/toModifiedJulianDay.cpp

@@ -157,10 +157,7 @@ namespace DB
 
         Monotonicity getMonotonicityForRange(const IDataType &, const Field &, const Field &) const override
         {
-            return Monotonicity(
+            return { .is_monotonic = true, .is_always_monotonic = true };
-                true,  // is_monotonic
-                true,  // is_positive
-                true); // is_always_monotonic
         }
 
     private:

src/Functions/toStartOfInterval.cpp

@@ -311,7 +311,7 @@ public:
 
     Monotonicity getMonotonicityForRange(const IDataType &, const Field &, const Field &) const override
     {
-        return { true, true, true };
+        return { .is_monotonic = true, .is_always_monotonic = true };
     }
 
 private:

src/Functions/toTimezone.cpp

@@ -66,7 +66,8 @@ public:
 
     Monotonicity getMonotonicityForRange(const IDataType & /*type*/, const Field & /*left*/, const Field & /*right*/) const override
     {
-        return {is_constant_timezone, is_constant_timezone, is_constant_timezone};
+        const bool b = is_constant_timezone;
+        return { .is_monotonic = b, .is_positive = b, .is_always_monotonic = b };
     }
 
 private:

src/Interpreters/AddDefaultDatabaseVisitor.h

@@ -11,6 +11,7 @@
 #include <Parsers/ASTTablesInSelectQuery.h>
 #include <Parsers/ASTFunction.h>
 #include <Parsers/DumpASTNode.h>
+#include <Parsers/ASTAlterQuery.h>
 #include <Interpreters/DatabaseAndTableWithAlias.h>
 #include <Interpreters/IdentifierSemantic.h>
 
@@ -36,7 +37,8 @@ public:
     {
         visitDDLChildren(ast);
 
-        if (!tryVisitDynamicCast<ASTQueryWithTableAndOutput>(ast) &&
+        if (!tryVisitDynamicCast<ASTAlterQuery>(ast) &&
+            !tryVisitDynamicCast<ASTQueryWithTableAndOutput>(ast) &&
             !tryVisitDynamicCast<ASTRenameQuery>(ast) &&
             !tryVisitDynamicCast<ASTFunction>(ast))
         {}
@@ -194,6 +196,24 @@ private:
         }
     }
 
+    void visitDDL(ASTAlterQuery & node, ASTPtr &) const
+    {
+        if (only_replace_current_database_function)
+            return;
+
+        if (node.database.empty())
+            node.database = database_name;
+
+        for (const auto & child : node.command_list->children)
+        {
+            auto * command_ast = child->as<ASTAlterCommand>();
+            if (command_ast->from_database.empty())
+                command_ast->from_database = database_name;
+            if (command_ast->to_database.empty())
+                command_ast->to_database = database_name;
+        }
+    }
+
     void visitDDL(ASTFunction & function, ASTPtr & node) const
     {
         if (function.name == "currentDatabase")

src/Interpreters/ExpressionJIT.cpp

@@ -239,7 +239,9 @@ public:
         const IDataType * type_ptr = &type;
         Field left_mut = left;
         Field right_mut = right;
-        Monotonicity result(true, true, true);
+
+        Monotonicity result = { .is_monotonic = true, .is_positive = true, .is_always_monotonic = true };
+
         /// monotonicity is only defined for unary functions, so the chain must describe a sequence of nested calls
         for (size_t i = 0; i < nested_functions.size(); ++i)
         {

src/Interpreters/MonotonicityCheckVisitor.h

@@ -28,7 +28,9 @@ public:
         const TablesWithColumns & tables;
         ContextPtr context;
         const std::unordered_set<String> & group_by_function_hashes;
-        Monotonicity monotonicity{true, true, true};
+
+        Monotonicity monotonicity = { .is_monotonic = true, .is_positive = true, .is_always_monotonic = true };
+
         ASTIdentifier * identifier = nullptr;
         DataTypePtr arg_data_type = {};
 

src/Server/HTTP/WriteBufferFromHTTPServerResponse.cpp

@@ -87,9 +87,14 @@ void WriteBufferFromHTTPServerResponse::finishSendHeaders()
 
 void WriteBufferFromHTTPServerResponse::nextImpl()
 {
+    if (!initialized)
     {
         std::lock_guard lock(mutex);
 
+        /// Initialize as early as possible since if the code throws,
+        /// next() should not be called anymore.
+        initialized = true;
+
         startSendHeaders();
 
         if (!out && !is_http_method_head)
@@ -174,6 +179,8 @@ void WriteBufferFromHTTPServerResponse::finalize()
         if (out)
             out->finalize();
         out.reset();
+        /// Catch write-after-finalize bugs.
+        set(nullptr, 0);
     }
     catch (...)
     {

src/Server/HTTP/WriteBufferFromHTTPServerResponse.h

@@ -46,6 +46,7 @@ private:
     std::shared_ptr<std::ostream> response_header_ostr;
 
     std::unique_ptr<WriteBuffer> out;
+    bool initialized = false;
 
     bool headers_started_sending = false;
     bool headers_finished_sending = false;    /// If true, you could not add any headers.

src/Server/HTTPHandler.cpp

@@ -13,7 +13,6 @@
 #include <IO/ReadBufferFromIStream.h>
 #include <IO/ReadBufferFromString.h>
 #include <IO/WriteBufferFromFile.h>
-#include <Server/HTTP/WriteBufferFromHTTPServerResponse.h>
 #include <IO/WriteBufferFromString.h>
 #include <IO/WriteBufferFromTemporaryFile.h>
 #include <IO/WriteHelpers.h>
@@ -757,76 +756,84 @@ void HTTPHandler::processQuery(
     }
 
     /// Send HTTP headers with code 200 if no exception happened and the data is still not sent to the client.
-    used_output.out->finalize();
+    used_output.finalize();
 }
 
 void HTTPHandler::trySendExceptionToClient(
     const std::string & s, int exception_code, HTTPServerRequest & request, HTTPServerResponse & response, Output & used_output)
+try
 {
+    response.set("X-ClickHouse-Exception-Code", toString<int>(exception_code));
+
+    /// FIXME: make sure that no one else is reading from the same stream at the moment.
+
+    /// If HTTP method is POST and Keep-Alive is turned on, we should read the whole request body
+    /// to avoid reading part of the current request body in the next request.
+    if (request.getMethod() == Poco::Net::HTTPRequest::HTTP_POST
+        && response.getKeepAlive()
+        && exception_code != ErrorCodes::HTTP_LENGTH_REQUIRED
+        && !request.getStream().eof())
+    {
+        request.getStream().ignoreAll();
+    }
+
+    if (exception_code == ErrorCodes::REQUIRED_PASSWORD)
+    {
+        response.requireAuthentication("ClickHouse server HTTP API");
+    }
+    else
+    {
+        response.setStatusAndReason(exceptionCodeToHTTPStatus(exception_code));
+    }
+
+    if (!response.sent() && !used_output.out_maybe_compressed)
+    {
+        /// If nothing was sent yet and we don't even know if we must compress the response.
+        *response.send() << s << std::endl;
+    }
+    else if (used_output.out_maybe_compressed)
+    {
+        /// Destroy CascadeBuffer to actualize buffers' positions and reset extra references
+        if (used_output.hasDelayed())
+            used_output.out_maybe_delayed_and_compressed.reset();
+
+        /// Send the error message into already used (and possibly compressed) stream.
+        /// Note that the error message will possibly be sent after some data.
+        /// Also HTTP code 200 could have already been sent.
+
+        /// If buffer has data, and that data wasn't sent yet, then no need to send that data
+        bool data_sent = used_output.out->count() != used_output.out->offset();
+
+        if (!data_sent)
+        {
+            used_output.out_maybe_compressed->position() = used_output.out_maybe_compressed->buffer().begin();
+            used_output.out->position() = used_output.out->buffer().begin();
+        }
+
+        writeString(s, *used_output.out_maybe_compressed);
+        writeChar('\n', *used_output.out_maybe_compressed);
+
+        used_output.out_maybe_compressed->next();
+    }
+    else
+    {
+        assert(false);
+        __builtin_unreachable();
+    }
+
+    used_output.finalize();
+}
+catch (...)
+{
+    tryLogCurrentException(log, "Cannot send exception to client");
+
     try
     {
-        response.set("X-ClickHouse-Exception-Code", toString<int>(exception_code));
+        used_output.finalize();
-
-        /// FIXME: make sure that no one else is reading from the same stream at the moment.
-
-        /// If HTTP method is POST and Keep-Alive is turned on, we should read the whole request body
-        /// to avoid reading part of the current request body in the next request.
-        if (request.getMethod() == Poco::Net::HTTPRequest::HTTP_POST
-            && response.getKeepAlive()
-            && exception_code != ErrorCodes::HTTP_LENGTH_REQUIRED
-            && !request.getStream().eof())
-        {
-            request.getStream().ignoreAll();
-        }
-
-        if (exception_code == ErrorCodes::REQUIRED_PASSWORD)
-        {
-            response.requireAuthentication("ClickHouse server HTTP API");
-        }
-        else
-        {
-            response.setStatusAndReason(exceptionCodeToHTTPStatus(exception_code));
-        }
-
-        if (!response.sent() && !used_output.out_maybe_compressed)
-        {
-            /// If nothing was sent yet and we don't even know if we must compress the response.
-            *response.send() << s << std::endl;
-        }
-        else if (used_output.out_maybe_compressed)
-        {
-            /// Destroy CascadeBuffer to actualize buffers' positions and reset extra references
-            if (used_output.hasDelayed())
-                used_output.out_maybe_delayed_and_compressed.reset();
-
-            /// Send the error message into already used (and possibly compressed) stream.
-            /// Note that the error message will possibly be sent after some data.
-            /// Also HTTP code 200 could have already been sent.
-
-            /// If buffer has data, and that data wasn't sent yet, then no need to send that data
-            bool data_sent = used_output.out->count() != used_output.out->offset();
-
-            if (!data_sent)
-            {
-                used_output.out_maybe_compressed->position() = used_output.out_maybe_compressed->buffer().begin();
-                used_output.out->position() = used_output.out->buffer().begin();
-            }
-
-            writeString(s, *used_output.out_maybe_compressed);
-            writeChar('\n', *used_output.out_maybe_compressed);
-
-            used_output.out_maybe_compressed->next();
-            used_output.out->finalize();
-        }
-        else
-        {
-            assert(false);
-            __builtin_unreachable();
-        }
     }
     catch (...)
     {
-        tryLogCurrentException(log, "Cannot send exception to client");
+        tryLogCurrentException(log, "Cannot flush data to client (after sending exception)");
     }
 }
 
@@ -885,8 +892,7 @@ void HTTPHandler::handleRequest(HTTPServerRequest & request, HTTPServerResponse
         trySendExceptionToClient(exception_message, exception_code, request, response, used_output);
     }
 
-    if (used_output.out)
+    used_output.finalize();
-        used_output.out->finalize();
 }
 
 DynamicQueryHandler::DynamicQueryHandler(IServer & server_, const std::string & param_name_)

src/Server/HTTPHandler.h

@@ -3,6 +3,7 @@
 #include <Core/Names.h>
 #include <Server/HTTP/HTMLForm.h>
 #include <Server/HTTP/HTTPRequestHandler.h>
+#include <Server/HTTP/WriteBufferFromHTTPServerResponse.h>
 #include <Common/CurrentMetrics.h>
 #include <Common/CurrentThread.h>
 
@@ -63,6 +64,16 @@ private:
         {
             return out_maybe_delayed_and_compressed != out_maybe_compressed;
         }
+
+        inline void finalize() const
+        {
+            if (out_maybe_delayed_and_compressed)
+                out_maybe_delayed_and_compressed->finalize();
+            if (out_maybe_compressed)
+                out_maybe_compressed->finalize();
+            if (out)
+                out->finalize();
+        }
     };
 
     IServer & server;

src/Storages/tests/gtest_transform_query_for_external_database.cpp

@@ -249,3 +249,22 @@ TEST(TransformQueryForExternalDatabase, Strict)
     /// !isCompatible() takes place
     EXPECT_THROW(check(state, 1, "SELECT column FROM test.table WHERE left(column, 10) = RIGHT(column, 10) AND SUBSTRING(column FROM 1 FOR 2) = 'Hello'", ""), Exception);
 }
+
+TEST(TransformQueryForExternalDatabase, Null)
+{
+    const State & state = State::instance();
+
+    check(state, 1,
+          "SELECT field FROM table WHERE field IS NULL",
+          R"(SELECT "field" FROM "test"."table" WHERE "field" IS NULL)");
+    check(state, 1,
+          "SELECT field FROM table WHERE field IS NOT NULL",
+          R"(SELECT "field" FROM "test"."table" WHERE "field" IS NOT NULL)");
+
+    check(state, 1,
+          "SELECT field FROM table WHERE isNull(field)",
+          R"(SELECT "field" FROM "test"."table" WHERE "field" IS NULL)");
+    check(state, 1,
+          "SELECT field FROM table WHERE isNotNull(field)",
+          R"(SELECT "field" FROM "test"."table" WHERE "field" IS NOT NULL)");
+}

src/Storages/transformQueryForExternalDatabase.cpp

@@ -132,6 +132,8 @@ bool isCompatible(IAST & node)
             || name == "notLike"
             || name == "in"
             || name == "notIn"
+            || name == "isNull"
+            || name == "isNotNull"
             || name == "tuple"))
             return false;
 

tests/integration/test_storage_mysql/test.py

@@ -449,6 +449,38 @@ def test_mysql_in(started_cluster):
     drop_mysql_table(conn, table_name)
     conn.close()
 
+def test_mysql_null(started_cluster):
+    table_name = 'test_mysql_in'
+    node1.query(f'DROP TABLE IF EXISTS {table_name}')
+
+    conn = get_mysql_conn(started_cluster, cluster.mysql_ip)
+    drop_mysql_table(conn, table_name)
+    with conn.cursor() as cursor:
+        cursor.execute("""
+            CREATE TABLE `clickhouse`.`{}` (
+            `id` int(11) NOT NULL,
+            `money` int NULL default NULL,
+            PRIMARY KEY (`id`)) ENGINE=InnoDB;
+        """.format(table_name))
+
+    node1.query('''
+        CREATE TABLE {}
+        (
+            id UInt32,
+            money Nullable(UInt32)
+        )
+        ENGINE = MySQL('mysql57:3306', 'clickhouse', '{}', 'root', 'clickhouse')
+        '''.format(table_name, table_name)
+    )
+
+    node1.query("INSERT INTO {} (id, money) SELECT number, if(number%2, NULL, 1) from numbers(10) ".format(table_name))
+
+    assert int(node1.query("SELECT count() FROM {} WHERE money IS NULL SETTINGS external_table_strict_query=1".format(table_name))) == 5
+    assert int(node1.query("SELECT count() FROM {} WHERE money IS NOT NULL SETTINGS external_table_strict_query=1".format(table_name))) == 5
+
+    drop_mysql_table(conn, table_name)
+    conn.close()
+
 
 if __name__ == '__main__':
     with contextmanager(started_cluster)() as cluster:

tests/queries/0_stateless/02010_lc_native.sh

@@ -8,6 +8,6 @@ $CLICKHOUSE_CLIENT -q "drop table if exists tab;"
 $CLICKHOUSE_CLIENT -q "create table tab(x LowCardinality(String)) engine = MergeTree order by tuple();"
 
 # We should have correct env vars from shell_config.sh to run this test
-python3 "$CURDIR"/2010_lc_native.python
+python3 "$CURDIR"/02010_lc_native.python
 
 $CLICKHOUSE_CLIENT -q "drop table if exists tab;"

tests/queries/0_stateless/02020_alter_table_modify_comment.reference

@@ -118,27 +118,27 @@ re-attach table
 CREATE TABLE default.comment_test_table\n(\n    `k` UInt64,\n    `s` String\n)\nENGINE = TinyLog\nCOMMENT \'another comment on a table\'
 comment=	another comment on a table
 
-engine : ReplicatedMergeTree('/clickhouse/2020_alter_table_modify_comment_default', '1') ORDER BY k
+engine : ReplicatedMergeTree('/clickhouse/02020_alter_table_modify_comment_default', '1') ORDER BY k
 initial comment
-CREATE TABLE default.comment_test_table\n(\n    `k` UInt64,\n    `s` String\n)\nENGINE = ReplicatedMergeTree(\'/clickhouse/2020_alter_table_modify_comment_default\', \'1\')\nORDER BY k\nSETTINGS index_granularity = 8192\nCOMMENT \'Test table with comment\'
+CREATE TABLE default.comment_test_table\n(\n    `k` UInt64,\n    `s` String\n)\nENGINE = ReplicatedMergeTree(\'/clickhouse/02020_alter_table_modify_comment_default\', \'1\')\nORDER BY k\nSETTINGS index_granularity = 8192\nCOMMENT \'Test table with comment\'
 comment=	Test table with comment
 
 change a comment
-CREATE TABLE default.comment_test_table\n(\n    `k` UInt64,\n    `s` String\n)\nENGINE = ReplicatedMergeTree(\'/clickhouse/2020_alter_table_modify_comment_default\', \'1\')\nORDER BY k\nSETTINGS index_granularity = 8192\nCOMMENT \'Test table with comment\'
+CREATE TABLE default.comment_test_table\n(\n    `k` UInt64,\n    `s` String\n)\nENGINE = ReplicatedMergeTree(\'/clickhouse/02020_alter_table_modify_comment_default\', \'1\')\nORDER BY k\nSETTINGS index_granularity = 8192\nCOMMENT \'Test table with comment\'
 comment=	Test table with comment
 
 remove a comment
-CREATE TABLE default.comment_test_table\n(\n    `k` UInt64,\n    `s` String\n)\nENGINE = ReplicatedMergeTree(\'/clickhouse/2020_alter_table_modify_comment_default\', \'1\')\nORDER BY k\nSETTINGS index_granularity = 8192\nCOMMENT \'Test table with comment\'
+CREATE TABLE default.comment_test_table\n(\n    `k` UInt64,\n    `s` String\n)\nENGINE = ReplicatedMergeTree(\'/clickhouse/02020_alter_table_modify_comment_default\', \'1\')\nORDER BY k\nSETTINGS index_granularity = 8192\nCOMMENT \'Test table with comment\'
 comment=	Test table with comment
 
 add a comment back
-CREATE TABLE default.comment_test_table\n(\n    `k` UInt64,\n    `s` String\n)\nENGINE = ReplicatedMergeTree(\'/clickhouse/2020_alter_table_modify_comment_default\', \'1\')\nORDER BY k\nSETTINGS index_granularity = 8192\nCOMMENT \'Test table with comment\'
+CREATE TABLE default.comment_test_table\n(\n    `k` UInt64,\n    `s` String\n)\nENGINE = ReplicatedMergeTree(\'/clickhouse/02020_alter_table_modify_comment_default\', \'1\')\nORDER BY k\nSETTINGS index_granularity = 8192\nCOMMENT \'Test table with comment\'
 comment=	Test table with comment
 
 detach table
-CREATE TABLE default.comment_test_table\n(\n    `k` UInt64,\n    `s` String\n)\nENGINE = ReplicatedMergeTree(\'/clickhouse/2020_alter_table_modify_comment_default\', \'1\')\nORDER BY k\nSETTINGS index_granularity = 8192\nCOMMENT \'Test table with comment\'
+CREATE TABLE default.comment_test_table\n(\n    `k` UInt64,\n    `s` String\n)\nENGINE = ReplicatedMergeTree(\'/clickhouse/02020_alter_table_modify_comment_default\', \'1\')\nORDER BY k\nSETTINGS index_granularity = 8192\nCOMMENT \'Test table with comment\'
 
 re-attach table
-CREATE TABLE default.comment_test_table\n(\n    `k` UInt64,\n    `s` String\n)\nENGINE = ReplicatedMergeTree(\'/clickhouse/2020_alter_table_modify_comment_default\', \'1\')\nORDER BY k\nSETTINGS index_granularity = 8192\nCOMMENT \'Test table with comment\'
+CREATE TABLE default.comment_test_table\n(\n    `k` UInt64,\n    `s` String\n)\nENGINE = ReplicatedMergeTree(\'/clickhouse/02020_alter_table_modify_comment_default\', \'1\')\nORDER BY k\nSETTINGS index_granularity = 8192\nCOMMENT \'Test table with comment\'
 comment=	Test table with comment
 

tests/queries/0_stateless/02028_add_default_database_for_alterquery_on_cluster.reference

@@ -0,0 +1,7 @@
+localhost	9000	0		0	0
+localhost	9000	0		0	0
+localhost	9000	0		0	0
+localhost	9000	0		0	0
+localhost	9000	0		0	0
+localhost	9000	0		0	0
+localhost	9000	0		0	0

tests/queries/0_stateless/02028_add_default_database_for_alterquery_on_cluster.sql

@@ -0,0 +1,19 @@
+-- Tags: distributed, no-parallel, no-replicated-database
+-- Tag no-replicated-database: ON CLUSTER is not allowed
+
+DROP DATABASE IF EXISTS 02028_db ON CLUSTER test_shard_localhost;
+CREATE DATABASE 02028_db ON CLUSTER test_shard_localhost;
+USE 02028_db;
+
+CREATE TABLE t1_local ON CLUSTER test_shard_localhost(partition_col_1 String, tc1 int,tc2 int)ENGINE=MergeTree() PARTITION BY partition_col_1 ORDER BY tc1;
+CREATE TABLE t2_local ON CLUSTER test_shard_localhost(partition_col_1 String, tc1 int,tc2 int)ENGINE=MergeTree() PARTITION BY partition_col_1 ORDER BY tc1;
+
+INSERT INTO t1_local VALUES('partition1', 1,1);
+INSERT INTO t1_local VALUES('partition2', 1,1);
+INSERT INTO t2_local VALUES('partition1', 3,3);
+INSERT INTO t2_local VALUES('partition2', 6,6);
+
+ALTER TABLE t1_local ON CLUSTER test_shard_localhost REPLACE PARTITION 'partition1' FROM  t2_local;
+ALTER TABLE t1_local ON CLUSTER test_shard_localhost MOVE PARTITION 'partition2' TO TABLE t2_local;
+
+DROP DATABASE 02028_db ON CLUSTER test_shard_localhost;