Merge pull request #11832 from ClickHouse/mysql-vars

Added support for MySQL style global variables syntax

programs/client/Client.cpp

@@ -398,6 +398,7 @@ private:
             { TokenType::GreaterOrEquals, Replxx::Color::INTENSE },
             { TokenType::Concatenation, Replxx::Color::INTENSE },
             { TokenType::At, Replxx::Color::INTENSE },
+            { TokenType::DoubleAt, Replxx::Color::MAGENTA },
 
             { TokenType::EndOfStream, Replxx::Color::DEFAULT },
 

src/Functions/FunctionsConversion.cpp

@@ -11,6 +11,8 @@ FunctionOverloadResolverImplPtr CastOverloadResolver::create(const Context & con
     return createImpl(context.getSettingsRef().cast_keep_nullable);
 }
 
+void registerFunctionFixedString(FunctionFactory & factory);
+
 void registerFunctionsConversion(FunctionFactory & factory)
 {
     factory.registerFunction<FunctionToUInt8>();
@@ -33,7 +35,8 @@ void registerFunctionsConversion(FunctionFactory & factory)
     factory.registerFunction<FunctionToDateTime64>();
     factory.registerFunction<FunctionToUUID>();
     factory.registerFunction<FunctionToString>();
-    factory.registerFunction<FunctionToFixedString>();
+
+    registerFunctionFixedString(factory);
 
     factory.registerFunction<FunctionToUnixTimestamp>();
     factory.registerFunction<CastOverloadResolver>(FunctionFactory::CaseInsensitive);

src/Functions/FunctionsConversion.h

@@ -41,6 +41,7 @@
 #include <Functions/DateTimeTransforms.h>
 #include <DataTypes/DataTypeLowCardinality.h>
 #include <Columns/ColumnLowCardinality.h>
+#include <Functions/toFixedString.h>
 
 
 namespace DB
@@ -58,7 +59,6 @@ namespace ErrorCodes
     extern const int CANNOT_PARSE_DATETIME;
     extern const int CANNOT_PARSE_TEXT;
     extern const int CANNOT_PARSE_UUID;
-    extern const int TOO_LARGE_STRING_SIZE;
     extern const int TOO_FEW_ARGUMENTS_FOR_FUNCTION;
     extern const int LOGICAL_ERROR;
     extern const int TYPE_MISMATCH;
@@ -1262,94 +1262,6 @@ public:
     }
 };
 
-/** Conversion to fixed string is implemented only for strings.
-  */
-class FunctionToFixedString : public IFunction
-{
-public:
-    static constexpr auto name = "toFixedString";
-    static FunctionPtr create(const Context &) { return std::make_shared<FunctionToFixedString>(); }
-    static FunctionPtr create() { return std::make_shared<FunctionToFixedString>(); }
-
-    String getName() const override
-    {
-        return name;
-    }
-
-    size_t getNumberOfArguments() const override { return 2; }
-    bool isInjective(const Block &) const override { return true; }
-
-    DataTypePtr getReturnTypeImpl(const ColumnsWithTypeAndName & arguments) const override
-    {
-        if (!isUnsignedInteger(arguments[1].type))
-            throw Exception("Second argument for function " + getName() + " must be unsigned integer", ErrorCodes::ILLEGAL_COLUMN);
-        if (!arguments[1].column)
-            throw Exception("Second argument for function " + getName() + " must be constant", ErrorCodes::ILLEGAL_COLUMN);
-        if (!isStringOrFixedString(arguments[0].type))
-            throw Exception(getName() + " is only implemented for types String and FixedString", ErrorCodes::NOT_IMPLEMENTED);
-
-        const size_t n = arguments[1].column->getUInt(0);
-        return std::make_shared<DataTypeFixedString>(n);
-    }
-
-    bool useDefaultImplementationForConstants() const override { return true; }
-    ColumnNumbers getArgumentsThatAreAlwaysConstant() const override { return {1}; }
-
-    void executeImpl(Block & block, const ColumnNumbers & arguments, size_t result, size_t /*input_rows_count*/) override
-    {
-        const auto n = block.getByPosition(arguments[1]).column->getUInt(0);
-        return executeForN(block, arguments, result, n);
-    }
-
-    static void executeForN(Block & block, const ColumnNumbers & arguments, const size_t result, const size_t n)
-    {
-        const auto & column = block.getByPosition(arguments[0]).column;
-
-        if (const auto column_string = checkAndGetColumn<ColumnString>(column.get()))
-        {
-            auto column_fixed = ColumnFixedString::create(n);
-
-            auto & out_chars = column_fixed->getChars();
-            const auto & in_chars = column_string->getChars();
-            const auto & in_offsets = column_string->getOffsets();
-
-            out_chars.resize_fill(in_offsets.size() * n);
-
-            for (size_t i = 0; i < in_offsets.size(); ++i)
-            {
-                const size_t off = i ? in_offsets[i - 1] : 0;
-                const size_t len = in_offsets[i] - off - 1;
-                if (len > n)
-                    throw Exception("String too long for type FixedString(" + toString(n) + ")",
-                        ErrorCodes::TOO_LARGE_STRING_SIZE);
-                memcpy(&out_chars[i * n], &in_chars[off], len);
-            }
-
-            block.getByPosition(result).column = std::move(column_fixed);
-        }
-        else if (const auto column_fixed_string = checkAndGetColumn<ColumnFixedString>(column.get()))
-        {
-            const auto src_n = column_fixed_string->getN();
-            if (src_n > n)
-                throw Exception{"String too long for type FixedString(" + toString(n) + ")", ErrorCodes::TOO_LARGE_STRING_SIZE};
-
-            auto column_fixed = ColumnFixedString::create(n);
-
-            auto & out_chars = column_fixed->getChars();
-            const auto & in_chars = column_fixed_string->getChars();
-            const auto size = column_fixed_string->size();
-            out_chars.resize_fill(size * n);
-
-            for (const auto i : ext::range(0, size))
-                memcpy(&out_chars[i * n], &in_chars[i * src_n], src_n);
-
-            block.getByPosition(result).column = std::move(column_fixed);
-        }
-        else
-            throw Exception("Unexpected column: " + column->getName(), ErrorCodes::ILLEGAL_COLUMN);
-    }
-};
-
 
 /// Monotonicity.
 

src/Functions/globalVariable.cpp

@@ -0,0 +1,68 @@
+#include <Functions/IFunctionImpl.h>
+#include <Functions/FunctionFactory.h>
+#include <Functions/FunctionHelpers.h>
+#include <DataTypes/DataTypeString.h>
+#include <Columns/ColumnString.h>
+#include <Columns/ColumnConst.h>
+#include <Core/Field.h>
+
+
+namespace DB
+{
+
+namespace ErrorCodes
+{
+    extern const int BAD_ARGUMENTS;
+}
+
+
+/** globalVariable('name') - takes constant string argument and returns the value of global variable with that name.
+  * It is intended for compatibility with MySQL.
+  *
+  * Currently it's a stub, no variables are implemented. Feel free to add more variables.
+  */
+class FunctionGlobalVariable : public IFunction
+{
+public:
+    static constexpr auto name = "globalVariable";
+    static FunctionPtr create(const Context &)
+    {
+        return std::make_shared<FunctionGlobalVariable>();
+    }
+
+    String getName() const override
+    {
+        return name;
+    }
+
+    size_t getNumberOfArguments() const override
+    {
+        return 1;
+    }
+
+    DataTypePtr getReturnTypeImpl(const ColumnsWithTypeAndName & arguments) const override
+    {
+        if (!checkColumnConst<ColumnString>(arguments[0].column.get()))
+            throw Exception("Agrument of function " + getName() + " must be constant string", ErrorCodes::BAD_ARGUMENTS);
+
+        String variable_name = assert_cast<const ColumnConst &>(*arguments[0].column).getValue<String>();
+
+        throw Exception("There is no global variable with name " + variable_name, ErrorCodes::BAD_ARGUMENTS);
+    }
+
+    void executeImpl(Block & block, const ColumnNumbers &, size_t /*result*/, size_t /*input_rows_count*/) override
+    {
+        String variable_name = assert_cast<const ColumnConst &>(*block.getByPosition(0).column).getValue<String>();
+
+        throw Exception("There is no global variable with name " + variable_name, ErrorCodes::BAD_ARGUMENTS);
+    }
+};
+
+
+void registerFunctionGlobalVariable(FunctionFactory & factory)
+{
+    factory.registerFunction<FunctionGlobalVariable>();
+}
+
+}
+

src/Functions/registerFunctionsMiscellaneous.cpp

@@ -56,6 +56,7 @@ void registerFunctionTransform(FunctionFactory &);
 void registerFunctionGetMacro(FunctionFactory &);
 void registerFunctionGetScalar(FunctionFactory &);
 void registerFunctionIsConstant(FunctionFactory &);
+void registerFunctionGlobalVariable(FunctionFactory &);
 
 #if USE_ICU
 void registerFunctionConvertCharset(FunctionFactory &);
@@ -112,6 +113,7 @@ void registerFunctionsMiscellaneous(FunctionFactory & factory)
     registerFunctionGetMacro(factory);
     registerFunctionGetScalar(factory);
     registerFunctionIsConstant(factory);
+    registerFunctionGlobalVariable(factory);
 
 #if USE_ICU
     registerFunctionConvertCharset(factory);

src/Functions/toFixedString.cpp

@@ -0,0 +1,13 @@
+#include <Functions/FunctionFactory.h>
+#include <Functions/toFixedString.h>
+
+
+namespace DB
+{
+
+void registerFunctionFixedString(FunctionFactory & factory)
+{
+    factory.registerFunction<FunctionToFixedString>();
+}
+
+}

src/Functions/toFixedString.h

@@ -0,0 +1,110 @@
+#include <Functions/IFunctionImpl.h>
+#include <DataTypes/DataTypeString.h>
+#include <DataTypes/DataTypeFixedString.h>
+#include <DataTypes/DataTypesNumber.h>
+#include <Columns/ColumnString.h>
+#include <Columns/ColumnFixedString.h>
+#include <IO/WriteHelpers.h>
+
+
+namespace DB
+{
+
+namespace ErrorCodes
+{
+    extern const int ILLEGAL_COLUMN;
+    extern const int TOO_LARGE_STRING_SIZE;
+    extern const int NOT_IMPLEMENTED;
+}
+
+
+/** Conversion to fixed string is implemented only for strings.
+  */
+class FunctionToFixedString : public IFunction
+{
+public:
+    static constexpr auto name = "toFixedString";
+    static FunctionPtr create(const Context &) { return std::make_shared<FunctionToFixedString>(); }
+    static FunctionPtr create() { return std::make_shared<FunctionToFixedString>(); }
+
+    String getName() const override
+    {
+        return name;
+    }
+
+    size_t getNumberOfArguments() const override { return 2; }
+    bool isInjective(const Block &) const override { return true; }
+
+    DataTypePtr getReturnTypeImpl(const ColumnsWithTypeAndName & arguments) const override
+    {
+        if (!isUnsignedInteger(arguments[1].type))
+            throw Exception("Second argument for function " + getName() + " must be unsigned integer", ErrorCodes::ILLEGAL_COLUMN);
+        if (!arguments[1].column)
+            throw Exception("Second argument for function " + getName() + " must be constant", ErrorCodes::ILLEGAL_COLUMN);
+        if (!isStringOrFixedString(arguments[0].type))
+            throw Exception(getName() + " is only implemented for types String and FixedString", ErrorCodes::NOT_IMPLEMENTED);
+
+        const size_t n = arguments[1].column->getUInt(0);
+        return std::make_shared<DataTypeFixedString>(n);
+    }
+
+    bool useDefaultImplementationForConstants() const override { return true; }
+    ColumnNumbers getArgumentsThatAreAlwaysConstant() const override { return {1}; }
+
+    void executeImpl(Block & block, const ColumnNumbers & arguments, size_t result, size_t /*input_rows_count*/) override
+    {
+        const auto n = block.getByPosition(arguments[1]).column->getUInt(0);
+        return executeForN(block, arguments, result, n);
+    }
+
+    static void executeForN(Block & block, const ColumnNumbers & arguments, const size_t result, const size_t n)
+    {
+        const auto & column = block.getByPosition(arguments[0]).column;
+
+        if (const auto column_string = checkAndGetColumn<ColumnString>(column.get()))
+        {
+            auto column_fixed = ColumnFixedString::create(n);
+
+            auto & out_chars = column_fixed->getChars();
+            const auto & in_chars = column_string->getChars();
+            const auto & in_offsets = column_string->getOffsets();
+
+            out_chars.resize_fill(in_offsets.size() * n);
+
+            for (size_t i = 0; i < in_offsets.size(); ++i)
+            {
+                const size_t off = i ? in_offsets[i - 1] : 0;
+                const size_t len = in_offsets[i] - off - 1;
+                if (len > n)
+                    throw Exception("String too long for type FixedString(" + toString(n) + ")",
+                        ErrorCodes::TOO_LARGE_STRING_SIZE);
+                memcpy(&out_chars[i * n], &in_chars[off], len);
+            }
+
+            block.getByPosition(result).column = std::move(column_fixed);
+        }
+        else if (const auto column_fixed_string = checkAndGetColumn<ColumnFixedString>(column.get()))
+        {
+            const auto src_n = column_fixed_string->getN();
+            if (src_n > n)
+                throw Exception{"String too long for type FixedString(" + toString(n) + ")", ErrorCodes::TOO_LARGE_STRING_SIZE};
+
+            auto column_fixed = ColumnFixedString::create(n);
+
+            auto & out_chars = column_fixed->getChars();
+            const auto & in_chars = column_fixed_string->getChars();
+            const auto size = column_fixed_string->size();
+            out_chars.resize_fill(size * n);
+
+            for (size_t i = 0; i < size; ++i)
+                memcpy(&out_chars[i * n], &in_chars[i * src_n], src_n);
+
+            block.getByPosition(result).column = std::move(column_fixed);
+        }
+        else
+            throw Exception("Unexpected column: " + column->getName(), ErrorCodes::ILLEGAL_COLUMN);
+    }
+};
+
+}
+

src/Functions/ya.make

@@ -200,6 +200,7 @@ SRCS(
     getMacro.cpp
     getScalar.cpp
     getSizeOfEnumType.cpp
+    globalVariable.cpp
     greatCircleDistance.cpp
     greater.cpp
     greaterOrEquals.cpp
@@ -374,6 +375,7 @@ SRCS(
     toDayOfMonth.cpp
     toDayOfWeek.cpp
     toDayOfYear.cpp
+    toFixedString.cpp
     toHour.cpp
     toISOWeek.cpp
     toISOYear.cpp

src/Parsers/ExpressionElementParsers.cpp

@@ -1254,6 +1254,37 @@ bool ParserSubstitution::parseImpl(Pos & pos, ASTPtr & node, Expected & expected
 }
 
 
+bool ParserMySQLGlobalVariable::parseImpl(Pos & pos, ASTPtr & node, Expected & expected)
+{
+    if (pos->type != TokenType::DoubleAt)
+        return false;
+
+    ++pos;
+
+    if (pos->type != TokenType::BareWord)
+    {
+        expected.add(pos, "variable name");
+        return false;
+    }
+
+    String name(pos->begin, pos->end);
+    ++pos;
+
+    auto name_literal = std::make_shared<ASTLiteral>(name);
+
+    auto expr_list_args = std::make_shared<ASTExpressionList>();
+    expr_list_args->children.push_back(std::move(name_literal));
+
+    auto function_node = std::make_shared<ASTFunction>();
+    function_node->name = "globalVariable";
+    function_node->arguments = expr_list_args;
+    function_node->children.push_back(expr_list_args);
+
+    node = function_node;
+    return true;
+}
+
+
 bool ParserExpressionElement::parseImpl(Pos & pos, ASTPtr & node, Expected & expected)
 {
     return ParserSubquery().parse(pos, node, expected)
@@ -1276,7 +1307,8 @@ bool ParserExpressionElement::parseImpl(Pos & pos, ASTPtr & node, Expected & exp
         || ParserQualifiedAsterisk().parse(pos, node, expected)
         || ParserAsterisk().parse(pos, node, expected)
         || ParserCompoundIdentifier().parse(pos, node, expected)
-        || ParserSubstitution().parse(pos, node, expected);
+        || ParserSubstitution().parse(pos, node, expected)
+        || ParserMySQLGlobalVariable().parse(pos, node, expected);
 }
 
 

src/Parsers/ExpressionElementParsers.h

@@ -301,6 +301,16 @@ protected:
 };
 
 
+/** MySQL-style global variable: @@var
+  */
+class ParserMySQLGlobalVariable : public IParserBase
+{
+protected:
+    const char * getName() const override { return "MySQL-style global variable"; }
+    bool parseImpl(Pos & pos, ASTPtr & node, Expected & expected) override;
+};
+
+
 /** The expression element is one of: an expression in parentheses, an array, a literal, a function, an identifier, an asterisk.
   */
 class ParserExpressionElement : public IParserBase

src/Parsers/Lexer.cpp

@@ -305,7 +305,12 @@ Token Lexer::nextTokenImpl()
             return Token(TokenType::ErrorSinglePipeMark, token_begin, pos);
         }
         case '@':
-            return Token(TokenType::At, token_begin, ++pos);
+        {
+            ++pos;
+            if (pos < end && *pos == '@')
+                return Token(TokenType::DoubleAt, token_begin, ++pos);
+            return Token(TokenType::At, token_begin, pos);
+        }
 
         default:
             if (isWordCharASCII(*pos))

src/Parsers/Lexer.h

@@ -48,7 +48,8 @@ namespace DB
     M(GreaterOrEquals) \
     M(Concatenation)          /** String concatenation operator: || */ \
     \
-    M(At)                     /** @. Used only for specifying user names. */ \
+    M(At)                     /** @. Used for specifying user names and also for MySQL-style variables. */ \
+    M(DoubleAt)               /** @@. Used for MySQL-style global variables. */ \
     \
     /** Order is important. EndOfStream goes after all usual tokens, and special error tokens goes after EndOfStream. */ \
     \

src/Processors/Formats/Impl/ConstantExpressionTemplate.cpp

@@ -1,15 +1,20 @@
 #include <Columns/ColumnConst.h>
+#include <Columns/ColumnTuple.h>
+#include <Columns/ColumnsNumber.h>
 #include <DataTypes/DataTypesNumber.h>
 #include <DataTypes/DataTypeNullable.h>
+#include <DataTypes/DataTypeString.h>
+#include <DataTypes/DataTypeArray.h>
+#include <DataTypes/DataTypeTuple.h>
 #include <DataTypes/FieldToDataType.h>
 #include <Processors/Formats/IRowInputFormat.h>
-#include <Functions/FunctionsConversion.h>
 #include <Functions/FunctionFactory.h>
 #include <Interpreters/ExpressionAnalyzer.h>
 #include <Interpreters/ReplaceQueryParameterVisitor.h>
 #include <Interpreters/SyntaxAnalyzer.h>
 #include <Interpreters/Context.h>
 #include <Interpreters/convertFieldToType.h>
+#include <Interpreters/ExpressionActions.h>
 #include <IO/ReadHelpers.h>
 #include <Parsers/ASTExpressionList.h>
 #include <Parsers/ASTFunction.h>

tests/queries/0_stateless/01337_mysql_global_variables.sql

@@ -0,0 +1 @@
+SELECT @@test; -- { serverError 36 }