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95 lines
3.4 KiB
C++
95 lines
3.4 KiB
C++
#include <Interpreters/Context.h>
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#include <Parsers/ASTFunction.h>
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#include <Storages/checkAndGetLiteralArgument.h>
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#include <Storages/StorageNull.h>
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#include <Interpreters/parseColumnsListForTableFunction.h>
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#include <TableFunctions/TableFunctionFactory.h>
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#include <Interpreters/evaluateConstantExpression.h>
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#include <DataTypes/DataTypesNumber.h>
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#include <TableFunctions/ITableFunction.h>
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#include "registerTableFunctions.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 NUMBER_OF_ARGUMENTS_DOESNT_MATCH;
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}
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namespace
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{
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/* null(structure) - creates a temporary null storage
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*
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* Used for testing purposes, for convenience writing tests and demos.
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*/
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class TableFunctionNull : public ITableFunction
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{
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public:
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static constexpr auto name = "null";
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std::string getName() const override { return name; }
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bool needStructureHint() const override { return structure == "auto"; }
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void setStructureHint(const ColumnsDescription & structure_hint_) override { structure_hint = structure_hint_; }
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private:
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StoragePtr executeImpl(const ASTPtr & ast_function, ContextPtr context, const String & table_name, ColumnsDescription cached_columns, bool is_insert_query) const override;
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const char * getStorageTypeName() const override { return "Null"; }
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void parseArguments(const ASTPtr & ast_function, ContextPtr context) override;
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ColumnsDescription getActualTableStructure(ContextPtr context, bool is_insert_query) const override;
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String structure = "auto";
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ColumnsDescription structure_hint;
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const ColumnsDescription default_structure{NamesAndTypesList{{"dummy", std::make_shared<DataTypeUInt8>()}}};
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};
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void TableFunctionNull::parseArguments(const ASTPtr & ast_function, ContextPtr context)
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{
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const auto * function = ast_function->as<ASTFunction>();
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if (!function || !function->arguments)
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throw Exception(ErrorCodes::NUMBER_OF_ARGUMENTS_DOESNT_MATCH, "Table function '{}' requires 'structure'", getName());
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const auto & arguments = function->arguments->children;
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if (!arguments.empty() && arguments.size() != 1)
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throw Exception(ErrorCodes::NUMBER_OF_ARGUMENTS_DOESNT_MATCH,
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"Table function '{}' requires 'structure' argument or empty argument", getName());
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if (!arguments.empty())
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structure = checkAndGetLiteralArgument<String>(evaluateConstantExpressionOrIdentifierAsLiteral(arguments[0], context), "structure");
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}
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ColumnsDescription TableFunctionNull::getActualTableStructure(ContextPtr context, bool /*is_insert_query*/) const
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{
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if (structure != "auto")
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return parseColumnsListFromString(structure, context);
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return default_structure;
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}
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StoragePtr TableFunctionNull::executeImpl(const ASTPtr & /*ast_function*/, ContextPtr context, const std::string & table_name, ColumnsDescription /*cached_columns*/, bool /*is_insert_query*/) const
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{
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ColumnsDescription columns;
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if (structure != "auto")
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columns = parseColumnsListFromString(structure, context);
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else if (!structure_hint.empty())
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columns = structure_hint;
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else
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columns = default_structure;
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auto res = std::make_shared<StorageNull>(StorageID(getDatabaseName(), table_name), columns, ConstraintsDescription(), String{});
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res->startup();
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return res;
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}
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}
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void registerTableFunctionNull(TableFunctionFactory & factory)
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{
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factory.registerFunction<TableFunctionNull>({.documentation = {}, .allow_readonly = true});
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}
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}
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