diff options
Diffstat (limited to 'src/backend')
| -rw-r--r-- | src/backend/optimizer/plan/planner.c | 39 |
1 files changed, 18 insertions, 21 deletions
diff --git a/src/backend/optimizer/plan/planner.c b/src/backend/optimizer/plan/planner.c index 879220c63e4..dc9053bca59 100644 --- a/src/backend/optimizer/plan/planner.c +++ b/src/backend/optimizer/plan/planner.c @@ -3440,7 +3440,6 @@ static List * reorder_grouping_sets(List *groupingsets, List *sortclause) { ListCell *lc; - ListCell *lc2; List *previous = NIL; List *result = NIL; @@ -3449,34 +3448,32 @@ reorder_grouping_sets(List *groupingsets, List *sortclause) List *candidate = lfirst(lc); List *new_elems = list_difference_int(candidate, previous); - if (list_length(new_elems) > 0) + while (list_length(sortclause) > list_length(previous) && + list_length(new_elems) > 0) { - while (list_length(sortclause) > list_length(previous)) - { - SortGroupClause *sc = list_nth(sortclause, list_length(previous)); - int ref = sc->tleSortGroupRef; + SortGroupClause *sc = list_nth(sortclause, list_length(previous)); + int ref = sc->tleSortGroupRef; - if (list_member_int(new_elems, ref)) - { - previous = lappend_int(previous, ref); - new_elems = list_delete_int(new_elems, ref); - } - else - { - /* diverged from the sortclause; give up on it */ - sortclause = NIL; - break; - } + if (list_member_int(new_elems, ref)) + { + previous = lappend_int(previous, ref); + new_elems = list_delete_int(new_elems, ref); } - - foreach(lc2, new_elems) + else { - previous = lappend_int(previous, lfirst_int(lc2)); + /* diverged from the sortclause; give up on it */ + sortclause = NIL; + break; } } + /* + * Safe to use list_concat (which shares cells of the second arg) + * because we know that new_elems does not share cells with anything. + */ + previous = list_concat(previous, new_elems); + result = lcons(list_copy(previous), result); - list_free(new_elems); } list_free(previous); |