ClickHouse/src/Interpreters/InterpreterDescribeQuery.cpp
Ivan 495c6e03aa
Replace all Context references with std::weak_ptr (#22297)
* Replace all Context references with std::weak_ptr

* Fix shared context captured by value

* Fix build

* Fix Context with named sessions

* Fix copy context

* Fix gcc build

* Merge with master and fix build

* Fix gcc-9 build
2021-04-11 02:33:54 +03:00

126 lines
3.7 KiB
C++

#include <Storages/IStorage.h>
#include <DataStreams/OneBlockInputStream.h>
#include <DataStreams/BlockIO.h>
#include <DataTypes/DataTypeString.h>
#include <Parsers/queryToString.h>
#include <Common/typeid_cast.h>
#include <TableFunctions/ITableFunction.h>
#include <TableFunctions/TableFunctionFactory.h>
#include <Interpreters/InterpreterSelectWithUnionQuery.h>
#include <Interpreters/Context.h>
#include <Interpreters/InterpreterDescribeQuery.h>
#include <Interpreters/IdentifierSemantic.h>
#include <Access/AccessFlags.h>
#include <Parsers/ASTIdentifier.h>
#include <Parsers/ASTFunction.h>
#include <Parsers/ASTTablesInSelectQuery.h>
#include <Parsers/TablePropertiesQueriesASTs.h>
namespace DB
{
BlockIO InterpreterDescribeQuery::execute()
{
BlockIO res;
res.in = executeImpl();
return res;
}
Block InterpreterDescribeQuery::getSampleBlock()
{
Block block;
ColumnWithTypeAndName col;
col.name = "name";
col.type = std::make_shared<DataTypeString>();
col.column = col.type->createColumn();
block.insert(col);
col.name = "type";
block.insert(col);
col.name = "default_type";
block.insert(col);
col.name = "default_expression";
block.insert(col);
col.name = "comment";
block.insert(col);
col.name = "codec_expression";
block.insert(col);
col.name = "ttl_expression";
block.insert(col);
return block;
}
BlockInputStreamPtr InterpreterDescribeQuery::executeImpl()
{
ColumnsDescription columns;
const auto & ast = query_ptr->as<ASTDescribeQuery &>();
const auto & table_expression = ast.table_expression->as<ASTTableExpression &>();
if (table_expression.subquery)
{
auto names_and_types = InterpreterSelectWithUnionQuery::getSampleBlock(
table_expression.subquery->children.at(0), getContext()).getNamesAndTypesList();
columns = ColumnsDescription(std::move(names_and_types));
}
else if (table_expression.table_function)
{
TableFunctionPtr table_function_ptr = TableFunctionFactory::instance().get(table_expression.table_function, getContext());
columns = table_function_ptr->getActualTableStructure(getContext());
}
else
{
auto table_id = getContext()->resolveStorageID(table_expression.database_and_table_name);
getContext()->checkAccess(AccessType::SHOW_COLUMNS, table_id);
auto table = DatabaseCatalog::instance().getTable(table_id, getContext());
auto table_lock = table->lockForShare(getContext()->getInitialQueryId(), getContext()->getSettingsRef().lock_acquire_timeout);
auto metadata_snapshot = table->getInMemoryMetadataPtr();
columns = metadata_snapshot->getColumns();
}
Block sample_block = getSampleBlock();
MutableColumns res_columns = sample_block.cloneEmptyColumns();
for (const auto & column : columns)
{
res_columns[0]->insert(column.name);
res_columns[1]->insert(column.type->getName());
if (column.default_desc.expression)
{
res_columns[2]->insert(toString(column.default_desc.kind));
res_columns[3]->insert(queryToString(column.default_desc.expression));
}
else
{
res_columns[2]->insertDefault();
res_columns[3]->insertDefault();
}
res_columns[4]->insert(column.comment);
if (column.codec)
res_columns[5]->insert(queryToString(column.codec->as<ASTFunction>()->arguments));
else
res_columns[5]->insertDefault();
if (column.ttl)
res_columns[6]->insert(queryToString(column.ttl));
else
res_columns[6]->insertDefault();
}
return std::make_shared<OneBlockInputStream>(sample_block.cloneWithColumns(std::move(res_columns)));
}
}