430a5952de
Traditionally, remove_useless_groupby_columns() was called during grouping_planner() directly after the call to preprocess_groupclause(). While in many ways, it made sense to populate the field and remove the functionally dependent columns from processed_groupClause at the same time, it's just that doing so had the disadvantage that remove_useless_groupby_columns() was being called before the RelOptInfos were populated for the relations mentioned in the query. Not having RelOptInfos available meant we needed to manually query the catalog tables to get the required details about the primary key constraint for the table. Here we move the remove_useless_groupby_columns() call to query_planner() and put it directly after the RelOptInfos are populated. This is fine to do as processed_groupClause still isn't final at this point as it can still be modified inside standard_qp_callback() by make_pathkeys_for_sortclauses_extended(). This commit is just a refactor and simply moves remove_useless_groupby_columns() into initsplan.c. A planned follow-up commit will adjust that function so it uses RelOptInfo instead of doing catalog lookups and also teach it how to use unique indexes as proofs to expand the cases where we can remove functionally dependent columns from the GROUP BY. Reviewed-by: Andrei Lepikhov, jian he Discussion: https://postgr.es/m/CAApHDvqLezKwoEBBQd0dp4Y9MDkFBDbny0f3SzEeqOFoU7Z5+A@mail.gmail.com
PostgreSQL Database Management System
This directory contains the source code distribution of the PostgreSQL database management system.
PostgreSQL is an advanced object-relational database management system that supports an extended subset of the SQL standard, including transactions, foreign keys, subqueries, triggers, user-defined types and functions. This distribution also contains C language bindings.
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