You can not select more than 25 topics Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.

Richard Guo 247dea89f7 Introduce an RTE for the grouping step ... If there are subqueries in the grouping expressions, each of these subqueries in the targetlist and HAVING clause is expanded into distinct SubPlan nodes. As a result, only one of these SubPlan nodes would be converted to reference to the grouping key column output by the Agg node; others would have to get evaluated afresh. This is not efficient, and with grouping sets this can cause wrong results issues in cases where they should go to NULL because they are from the wrong grouping set. Furthermore, during re-evaluation, these SubPlan nodes might use nulled column values from grouping sets, which is not correct. This issue is not limited to subqueries. For other types of expressions that are part of grouping items, if they are transformed into another form during preprocessing, they may fail to match lower target items. This can also lead to wrong results with grouping sets. To fix this issue, we introduce a new kind of RTE representing the output of the grouping step, with columns that are the Vars or expressions being grouped on. In the parser, we replace the grouping expressions in the targetlist and HAVING clause with Vars referencing this new RTE, so that the output of the parser directly expresses the semantic requirement that the grouping expressions be gotten from the grouping output rather than computed some other way. In the planner, we first preprocess all the columns of this new RTE and then replace any Vars in the targetlist and HAVING clause that reference this new RTE with the underlying grouping expressions, so that we will have only one instance of a SubPlan node for each subquery contained in the grouping expressions. Bump catversion because this changes the querytree produced by the parser. Thanks to Tom Lane for the idea to invent a new kind of RTE. Per reports from Geoff Winkless, Tobias Wendorff, Richard Guo from various threads. Author: Richard Guo Reviewed-by: Ashutosh Bapat, Sutou Kouhei Discussion: https://postgr.es/m/CAMbWs4_dp7e7oTwaiZeBX8+P1rXw4ThkZxh1QG81rhu9Z47VsQ@mail.gmail.com		1 year ago
..
analyze.h	Add RETURNING support to MERGE.	2 years ago
kwlist.h	Revert support for ALTER TABLE ... MERGE/SPLIT PARTITION(S) commands	1 year ago
parse_agg.h	Update copyright for 2024	2 years ago
parse_clause.h	Add basic JSON_TABLE() functionality	2 years ago
parse_coerce.h	Update copyright for 2024	2 years ago
parse_collate.h	Update copyright for 2024	2 years ago
parse_cte.h	Update copyright for 2024	2 years ago
parse_enr.h	Update copyright for 2024	2 years ago
parse_expr.h	Update copyright for 2024	2 years ago
parse_func.h	Update copyright for 2024	2 years ago
parse_merge.h	Update copyright for 2024	2 years ago
parse_node.h	Introduce an RTE for the grouping step	1 year ago
parse_oper.h	Update copyright for 2024	2 years ago
parse_param.h	Update copyright for 2024	2 years ago
parse_relation.h	Introduce an RTE for the grouping step	1 year ago
parse_target.h	Update copyright for 2024	2 years ago
parse_type.h	Add a const decoration	2 years ago
parse_utilcmd.h	Update copyright for 2024	2 years ago
parser.h	Update copyright for 2024	2 years ago
parsetree.h	Update copyright for 2024	2 years ago
scanner.h	Update copyright for 2024	2 years ago
scansup.h	Update copyright for 2024	2 years ago