ClickHouse/src/TableFunctions/TableFunctionMerge.cpp

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#include <Common/OptimizedRegularExpression.h>
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#include <Common/typeid_cast.h>
#include <Storages/StorageMerge.h>
#include <Parsers/ASTLiteral.h>
#include <Parsers/ASTFunction.h>
#include <TableFunctions/ITableFunction.h>
#include <Interpreters/evaluateConstantExpression.h>
#include <Interpreters/Context.h>
#include <Access/ContextAccess.h>
#include <TableFunctions/TableFunctionMerge.h>
#include <TableFunctions/TableFunctionFactory.h>
#include <TableFunctions/registerTableFunctions.h>
namespace DB
{
namespace ErrorCodes
{
extern const int NUMBER_OF_ARGUMENTS_DOESNT_MATCH;
extern const int UNKNOWN_TABLE;
}
namespace
{
[[noreturn]] void throwNoTablesMatchRegexp(const String & source_database, const String & source_table_regexp)
{
throw Exception(
"Error while executing table function merge. In database " + source_database
+ " no one matches regular expression: " + source_table_regexp,
ErrorCodes::UNKNOWN_TABLE);
}
}
void TableFunctionMerge::parseArguments(const ASTPtr & ast_function, ContextPtr context)
{
ASTs & args_func = ast_function->children;
if (args_func.size() != 1)
throw Exception("Table function 'merge' requires exactly 2 arguments"
" - name of source database and regexp for table names.",
ErrorCodes::NUMBER_OF_ARGUMENTS_DOESNT_MATCH);
ASTs & args = args_func.at(0)->children;
if (args.size() != 2)
throw Exception("Table function 'merge' requires exactly 2 arguments"
" - name of source database and regexp for table names.",
ErrorCodes::NUMBER_OF_ARGUMENTS_DOESNT_MATCH);
args[0] = evaluateConstantExpressionForDatabaseName(args[0], context);
args[1] = evaluateConstantExpressionAsLiteral(args[1], context);
source_database = args[0]->as<ASTLiteral &>().value.safeGet<String>();
source_table_regexp = args[1]->as<ASTLiteral &>().value.safeGet<String>();
}
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const Strings & TableFunctionMerge::getSourceTables(ContextPtr context) const
{
if (source_tables)
return *source_tables;
auto database = DatabaseCatalog::instance().getDatabase(source_database);
OptimizedRegularExpression re(source_table_regexp);
auto table_name_match = [&](const String & table_name_) { return re.match(table_name_); };
auto access = context->getAccess();
bool granted_show_on_all_tables = access->isGranted(AccessType::SHOW_TABLES, source_database);
bool granted_select_on_all_tables = access->isGranted(AccessType::SELECT, source_database);
source_tables.emplace();
for (auto it = database->getTablesIterator(context, table_name_match); it->isValid(); it->next())
{
if (!it->table())
continue;
bool granted_show = granted_show_on_all_tables || access->isGranted(AccessType::SHOW_TABLES, source_database, it->name());
if (!granted_show)
continue;
if (!granted_select_on_all_tables)
access->checkAccess(AccessType::SELECT, source_database, it->name());
source_tables->emplace_back(it->name());
}
if (source_tables->empty())
throwNoTablesMatchRegexp(source_database, source_table_regexp);
return *source_tables;
}
ColumnsDescription TableFunctionMerge::getActualTableStructure(ContextPtr context) const
{
for (const auto & table_name : getSourceTables(context))
{
auto storage = DatabaseCatalog::instance().tryGetTable(StorageID{source_database, table_name}, context);
if (storage)
return ColumnsDescription{storage->getInMemoryMetadataPtr()->getColumns().getAllPhysical()};
}
throwNoTablesMatchRegexp(source_database, source_table_regexp);
}
StoragePtr TableFunctionMerge::executeImpl(const ASTPtr & /*ast_function*/, ContextPtr context, const std::string & table_name, ColumnsDescription /*cached_columns*/) const
{
auto res = StorageMerge::create(
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StorageID(getDatabaseName(), table_name),
getActualTableStructure(context),
source_database,
getSourceTables(context),
context);
res->startup();
return res;
}
void registerTableFunctionMerge(TableFunctionFactory & factory)
{
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factory.registerFunction<TableFunctionMerge>();
}
}