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Merge pull request #51955 from ClickHouse/filter_system_databases

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Filter databases list before querying potentially slow fields
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Alexander Gololobov 2023-07-20 12:39:36 +02:00 committed by GitHub
commit e9a187eefe
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1 changed files with 36 additions and 2 deletions
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38
src/Storages/System/StorageSystemDatabases.cpp
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@ -5,6 +5,8 @@
#include <Interpreters/formatWithPossiblyHidingSecrets.h>
#include <Access/ContextAccess.h>
#include <Storages/System/StorageSystemDatabases.h>
#include <Storages/SelectQueryInfo.h>
#include <Storages/VirtualColumnUtils.h>
#include <Parsers/ASTCreateQuery.h>
#include <Common/logger_useful.h>
@ -69,20 +71,52 @@ static String getEngineFull(const ContextPtr & ctx, const DatabasePtr & database
return engine_full;
}
void StorageSystemDatabases::fillData(MutableColumns & res_columns, ContextPtr context, const SelectQueryInfo &) const
static ColumnPtr getFilteredDatabases(const Databases & databases, const SelectQueryInfo & query_info, ContextPtr context)
{
MutableColumnPtr name_column = ColumnString::create();
MutableColumnPtr engine_column = ColumnString::create();
MutableColumnPtr uuid_column = ColumnUUID::create();
for (const auto & [database_name, database] : databases)
{
if (database_name == DatabaseCatalog::TEMPORARY_DATABASE)
continue; /// We don't want to show the internal database for temporary tables in system.tables
name_column->insert(database_name);
engine_column->insert(database->getEngineName());
uuid_column->insert(database->getUUID());
}
Block block
{
ColumnWithTypeAndName(std::move(name_column), std::make_shared<DataTypeString>(), "name"),
ColumnWithTypeAndName(std::move(engine_column), std::make_shared<DataTypeString>(), "engine"),
ColumnWithTypeAndName(std::move(uuid_column), std::make_shared<DataTypeUUID>(), "uuid")
};
VirtualColumnUtils::filterBlockWithQuery(query_info.query, block, context);
return block.getByPosition(0).column;
}
void StorageSystemDatabases::fillData(MutableColumns & res_columns, ContextPtr context, const SelectQueryInfo & query_info) const
{
const auto access = context->getAccess();
const bool check_access_for_databases = !access->isGranted(AccessType::SHOW_DATABASES);
const auto databases = DatabaseCatalog::instance().getDatabases();
for (const auto & [database_name, database] : databases)
ColumnPtr filtered_databases_column = getFilteredDatabases(databases, query_info, context);
for (size_t i = 0; i < filtered_databases_column->size(); ++i)
{
auto database_name = filtered_databases_column->getDataAt(i).toString();
if (check_access_for_databases && !access->isGranted(AccessType::SHOW_DATABASES, database_name))
continue;
if (database_name == DatabaseCatalog::TEMPORARY_DATABASE)
continue; /// filter out the internal database for temporary tables in system.databases, asynchronous metric "NumberOfDatabases" behaves the same way
const auto & database = databases.at(database_name);
res_columns[0]->insert(database_name);
res_columns[1]->insert(database->getEngineName());
res_columns[2]->insert(context->getPath() + database->getDataPath());