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107 lines
4.4 KiB
C++
107 lines
4.4 KiB
C++
#include <Common/typeid_cast.h>
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#include <IO/WriteHelpers.h>
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#include <Storages/IStorage.h>
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#include <Parsers/ASTFunction.h>
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#include <Parsers/ASTIdentifier.h>
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#include <Parsers/ASTSelectQuery.h>
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#include <Parsers/ASTSelectWithUnionQuery.h>
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#include <Parsers/ASTSubquery.h>
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#include <Interpreters/interpretSubquery.h>
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#include <Interpreters/DatabaseAndTableWithAlias.h>
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namespace DB
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{
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std::shared_ptr<InterpreterSelectWithUnionQuery> interpretSubquery(
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const ASTPtr & table_expression, const Context & context, size_t subquery_depth, const Names & required_source_columns)
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{
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if (auto * expr = table_expression->as<ASTTableExpression>())
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{
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ASTPtr table;
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if (expr->subquery)
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table = expr->subquery;
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else if (expr->table_function)
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table = expr->table_function;
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else if (expr->database_and_table_name)
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table = expr->database_and_table_name;
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return interpretSubquery(table, context, subquery_depth, required_source_columns);
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}
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/// Subquery or table name. The name of the table is similar to the subquery `SELECT * FROM t`.
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const auto * subquery = table_expression->as<ASTSubquery>();
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const auto * function = table_expression->as<ASTFunction>();
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const auto * table = table_expression->as<ASTIdentifier>();
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if (!subquery && !table && !function)
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throw Exception("Table expression is undefined, Method: ExpressionAnalyzer::interpretSubquery." , ErrorCodes::LOGICAL_ERROR);
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/** The subquery in the IN / JOIN section does not have any restrictions on the maximum size of the result.
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* Because the result of this query is not the result of the entire query.
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* Constraints work instead
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* max_rows_in_set, max_bytes_in_set, set_overflow_mode,
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* max_rows_in_join, max_bytes_in_join, join_overflow_mode,
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* which are checked separately (in the Set, Join objects).
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*/
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Context subquery_context = context;
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Settings subquery_settings = context.getSettings();
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subquery_settings.max_result_rows = 0;
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subquery_settings.max_result_bytes = 0;
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/// The calculation of `extremes` does not make sense and is not necessary (if you do it, then the `extremes` of the subquery can be taken instead of the whole query).
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subquery_settings.extremes = 0;
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subquery_context.setSettings(subquery_settings);
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auto subquery_options = SelectQueryOptions(QueryProcessingStage::Complete, subquery_depth).subquery();
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ASTPtr query;
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if (table || function)
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{
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/// create ASTSelectQuery for "SELECT * FROM table" as if written by hand
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const auto select_with_union_query = std::make_shared<ASTSelectWithUnionQuery>();
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query = select_with_union_query;
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select_with_union_query->list_of_selects = std::make_shared<ASTExpressionList>();
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const auto select_query = std::make_shared<ASTSelectQuery>();
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select_with_union_query->list_of_selects->children.push_back(select_query);
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select_query->setExpression(ASTSelectQuery::Expression::SELECT, std::make_shared<ASTExpressionList>());
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const auto select_expression_list = select_query->select();
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NamesAndTypesList columns;
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/// get columns list for target table
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if (function)
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{
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auto query_context = const_cast<Context *>(&context.getQueryContext());
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const auto & storage = query_context->executeTableFunction(table_expression);
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columns = storage->getColumns().getOrdinary();
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select_query->addTableFunction(*const_cast<ASTPtr *>(&table_expression)); // XXX: const_cast should be avoided!
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}
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else
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{
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DatabaseAndTableWithAlias database_table(*table);
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const auto & storage = context.getTable(database_table.database, database_table.table);
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columns = storage->getColumns().getOrdinary();
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select_query->replaceDatabaseAndTable(database_table.database, database_table.table);
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}
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select_expression_list->children.reserve(columns.size());
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/// manually substitute column names in place of asterisk
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for (const auto & column : columns)
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select_expression_list->children.emplace_back(std::make_shared<ASTIdentifier>(column.name));
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}
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else
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{
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query = subquery->children.at(0);
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subquery_options.removeDuplicates();
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}
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return std::make_shared<InterpreterSelectWithUnionQuery>(query, subquery_context, subquery_options, required_source_columns);
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}
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}
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