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https://github.com/ClickHouse/ClickHouse.git
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89 lines
2.4 KiB
C++
89 lines
2.4 KiB
C++
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#include <Functions/IFunction.h>
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#include <Functions/FunctionFactory.h>
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#include <Interpreters/Context.h>
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#include <DataTypes/DataTypeArray.h>
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#include <DataTypes/DataTypeString.h>
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namespace DB
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{
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namespace ErrorCodes
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{
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extern const int ILLEGAL_TYPE_OF_ARGUMENT;
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}
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namespace
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{
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class FunctionCurrentSchemas : public IFunction
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{
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const String db_name;
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public:
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static constexpr auto name = "currentSchemas";
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static FunctionPtr create(ContextPtr context)
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{
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return std::make_shared<FunctionCurrentSchemas>(context->getCurrentDatabase());
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}
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explicit FunctionCurrentSchemas(const String & db_name_) :
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db_name{db_name_}
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{
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}
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String getName() const override
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{
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return name;
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}
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size_t getNumberOfArguments() const override
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{
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return 1;
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}
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DataTypePtr getReturnTypeImpl(const DataTypes & arguments) const override
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{
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// For compatibility, function implements the same signature as Postgres'
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const bool argument_is_valid = arguments.size() == 1 && isBool(arguments.front());
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if (!argument_is_valid)
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throw Exception(ErrorCodes::ILLEGAL_TYPE_OF_ARGUMENT, "Argument for function {} must be bool", getName());
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return std::make_shared<DataTypeArray>(std::make_shared<DataTypeString>());
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}
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bool isDeterministic() const override { return false; }
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bool isSuitableForShortCircuitArgumentsExecution(const DataTypesWithConstInfo & /*arguments*/) const override { return false; }
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ColumnPtr executeImpl(const ColumnsWithTypeAndName &, const DataTypePtr &, size_t input_rows_count) const override
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{
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return DataTypeArray(std::make_shared<DataTypeString>())
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.createColumnConst(input_rows_count, Array { db_name });
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}
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};
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}
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REGISTER_FUNCTION(CurrentSchema)
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{
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factory.registerFunction<FunctionCurrentSchemas>(FunctionDocumentation
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{
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.description=R"(
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Returns a single-element array with the name of the current database
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Requires a boolean parameter, but it is ignored actually. It is required just for compatibility with the implementation of this function in other DB engines.
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[example:common]
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)",
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.examples{
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{"common", "SELECT current_schemas(true);", "['default']"}
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}
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},
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FunctionFactory::CaseInsensitive);
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factory.registerAlias("current_schemas", FunctionCurrentSchemas::name, FunctionFactory::CaseInsensitive);
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}
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}
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