diff options
Diffstat (limited to 'src/backend/optimizer/plan/analyzejoins.c')
| -rw-r--r-- | src/backend/optimizer/plan/analyzejoins.c | 28 |
1 files changed, 25 insertions, 3 deletions
diff --git a/src/backend/optimizer/plan/analyzejoins.c b/src/backend/optimizer/plan/analyzejoins.c index 11d39336b1a..a6c17534f0a 100644 --- a/src/backend/optimizer/plan/analyzejoins.c +++ b/src/backend/optimizer/plan/analyzejoins.c @@ -581,6 +581,7 @@ query_supports_distinctness(Query *query) { if (query->distinctClause != NIL || query->groupClause != NIL || + query->groupingSets != NIL || query->hasAggs || query->havingQual || query->setOperations) @@ -649,10 +650,10 @@ query_is_distinct_for(Query *query, List *colnos, List *opids) } /* - * Similarly, GROUP BY guarantees uniqueness if all the grouped columns - * appear in colnos and operator semantics match. + * Similarly, GROUP BY without GROUPING SETS guarantees uniqueness if all + * the grouped columns appear in colnos and operator semantics match. */ - if (query->groupClause) + if (query->groupClause && !query->groupingSets) { foreach(l, query->groupClause) { @@ -668,6 +669,27 @@ query_is_distinct_for(Query *query, List *colnos, List *opids) if (l == NULL) /* had matches for all? */ return true; } + else if (query->groupingSets) + { + /* + * If we have grouping sets with expressions, we probably + * don't have uniqueness and analysis would be hard. Punt. + */ + if (query->groupClause) + return false; + + /* + * If we have no groupClause (therefore no grouping expressions), + * we might have one or many empty grouping sets. If there's just + * one, then we're returning only one row and are certainly unique. + * But otherwise, we know we're certainly not unique. + */ + if (list_length(query->groupingSets) == 1 && + ((GroupingSet *)linitial(query->groupingSets))->kind == GROUPING_SET_EMPTY) + return true; + else + return false; + } else { /* |