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| author | Tomas Vondra <tomas.vondra@postgresql.org> | 2021-03-18 17:45:38 +0100 |
|---|---|---|
| committer | Tomas Vondra <tomas.vondra@postgresql.org> | 2021-03-18 18:22:18 +0100 |
| commit | be45be9c33a85e72cdaeb9967e9f6d2d00199e09 (patch) | |
| tree | c728067c32404e7475ebf4c66561d7edf2dd35b3 /src/include/parser/parse_agg.h | |
| parent | cd91de0d17952b5763466cfa663e98318f26d357 (diff) | |
| download | postgresql-be45be9c33a85e72cdaeb9967e9f6d2d00199e09.tar.gz postgresql-be45be9c33a85e72cdaeb9967e9f6d2d00199e09.zip | |
Implement GROUP BY DISTINCT
With grouping sets, it's possible that some of the grouping sets are
duplicate. This is especially common with CUBE and ROLLUP clauses. For
example GROUP BY CUBE (a,b), CUBE (b,c) is equivalent to
GROUP BY GROUPING SETS (
(a, b, c),
(a, b, c),
(a, b, c),
(a, b),
(a, b),
(a, b),
(a),
(a),
(a),
(c, a),
(c, a),
(c, a),
(c),
(b, c),
(b),
()
)
Some of the grouping sets are calculated multiple times, which is mostly
unnecessary. This commit implements a new GROUP BY DISTINCT feature, as
defined in the SQL standard, which eliminates the duplicate sets.
Author: Vik Fearing
Reviewed-by: Erik Rijkers, Georgios Kokolatos, Tomas Vondra
Discussion: https://postgr.es/m/bf3805a8-d7d1-ae61-fece-761b7ff41ecc@postgresfriends.org
Diffstat (limited to 'src/include/parser/parse_agg.h')
| -rw-r--r-- | src/include/parser/parse_agg.h | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/src/include/parser/parse_agg.h b/src/include/parser/parse_agg.h index 0a2546c3ea9..4dea01752af 100644 --- a/src/include/parser/parse_agg.h +++ b/src/include/parser/parse_agg.h @@ -26,7 +26,7 @@ extern void transformWindowFuncCall(ParseState *pstate, WindowFunc *wfunc, extern void parseCheckAggregates(ParseState *pstate, Query *qry); -extern List *expand_grouping_sets(List *groupingSets, int limit); +extern List *expand_grouping_sets(List *groupingSets, bool groupDistinct, int limit); extern int get_aggregate_argtypes(Aggref *aggref, Oid *inputTypes); |