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131 lines
4.0 KiB
C++
131 lines
4.0 KiB
C++
#include <Storages/IStorage.h>
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#include <DataStreams/OneBlockInputStream.h>
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#include <DataStreams/BlockIO.h>
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#include <DataTypes/DataTypeString.h>
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#include <Parsers/queryToString.h>
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#include <Common/typeid_cast.h>
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#include <TableFunctions/ITableFunction.h>
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#include <TableFunctions/TableFunctionFactory.h>
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#include <Interpreters/InterpreterSelectWithUnionQuery.h>
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#include <Interpreters/Context.h>
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#include <Interpreters/InterpreterDescribeQuery.h>
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#include <Parsers/ASTIdentifier.h>
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#include <Parsers/ASTFunction.h>
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#include <Parsers/ASTTablesInSelectQuery.h>
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#include <Parsers/TablePropertiesQueriesASTs.h>
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namespace DB
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{
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BlockIO InterpreterDescribeQuery::execute()
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{
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BlockIO res;
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res.in = executeImpl();
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return res;
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}
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Block InterpreterDescribeQuery::getSampleBlock()
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{
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Block block;
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ColumnWithTypeAndName col;
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col.name = "name";
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col.type = std::make_shared<DataTypeString>();
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col.column = col.type->createColumn();
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block.insert(col);
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col.name = "type";
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block.insert(col);
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col.name = "default_type";
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block.insert(col);
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col.name = "default_expression";
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block.insert(col);
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return block;
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}
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BlockInputStreamPtr InterpreterDescribeQuery::executeImpl()
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{
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const ASTDescribeQuery & ast = typeid_cast<const ASTDescribeQuery &>(*query_ptr);
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NamesAndTypesList columns;
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ColumnDefaults column_defaults;
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StoragePtr table;
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auto table_expression = typeid_cast<const ASTTableExpression *>(ast.table_expression.get());
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if (table_expression->subquery)
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{
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columns = InterpreterSelectWithUnionQuery::getSampleBlock(table_expression->subquery->children[0], context).getNamesAndTypesList();
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}
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else
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{
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if (table_expression->table_function)
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{
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auto table_function = typeid_cast<const ASTFunction *>(table_expression->table_function.get());
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/// Get the table function
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TableFunctionPtr table_function_ptr = TableFunctionFactory::instance().get(table_function->name, context);
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/// Run it and remember the result
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table = table_function_ptr->execute(table_expression->table_function, context);
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}
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else
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{
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String database_name;
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String table_name;
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auto identifier = table_expression->database_and_table_name;
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if (identifier->children.size() > 2)
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throw Exception("Logical error: more than two components in table expression", ErrorCodes::LOGICAL_ERROR);
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if (identifier->children.size() > 1)
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{
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auto database_ptr = identifier->children[0];
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auto table_ptr = identifier->children[1];
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if (database_ptr)
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database_name = typeid_cast<ASTIdentifier &>(*database_ptr).name;
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if (table_ptr)
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table_name = typeid_cast<ASTIdentifier &>(*table_ptr).name;
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}
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else
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table_name = typeid_cast<ASTIdentifier &>(*identifier).name;
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table = context.getTable(database_name, table_name);
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}
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auto table_lock = table->lockStructure(false, __PRETTY_FUNCTION__);
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columns = table->getColumns().getAll();
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column_defaults = table->getColumns().defaults;
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}
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Block sample_block = getSampleBlock();
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MutableColumns res_columns = sample_block.cloneEmptyColumns();
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for (const auto & column : columns)
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{
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res_columns[0]->insert(column.name);
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res_columns[1]->insert(column.type->getName());
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const auto it = column_defaults.find(column.name);
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if (it == std::end(column_defaults))
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{
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res_columns[2]->insertDefault();
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res_columns[3]->insertDefault();
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}
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else
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{
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res_columns[2]->insert(toString(it->second.kind));
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res_columns[3]->insert(queryToString(it->second.expression));
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}
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}
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return std::make_shared<OneBlockInputStream>(sample_block.cloneWithColumns(std::move(res_columns)));
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}
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}
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