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#pragma once
#include <Analyzer/IQueryTreePass.h>
namespace DB
{
/** Transform functions to subcolumns. Enabled using setting optimize_functions_to_subcolumns.
* It can help to reduce amount of read data.
*
* Example: SELECT tupleElement(column, subcolumn) FROM test_table;
* Result: SELECT column.subcolumn FROM test_table;
*
* Example: SELECT length(array_column) FROM test_table;
* Result: SELECT array_column.size0 FROM test_table;
*
* Example: SELECT nullable_column IS NULL FROM test_table;
* Result: SELECT nullable_column.null FROM test_table;
*/
class FunctionToSubcolumnsPass final : public IQueryTreePass
{
public:
String getName() override { return "FunctionToSubcolumns"; }
String getDescription() override { return "Rewrite function to subcolumns, for example tupleElement(column, subcolumn) into column.subcolumn"; }
void run(QueryTreeNodePtr query_tree_node, ContextPtr context) override;
};
}
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