diff options
| author | Amit Kapila <akapila@postgresql.org> | 2018-09-14 10:05:45 +0530 |
|---|---|---|
| committer | Amit Kapila <akapila@postgresql.org> | 2018-09-14 10:05:45 +0530 |
| commit | 1ceb103e7d1e794c0b171b0594fc6936003eb4ab (patch) | |
| tree | 654e600860a858eb03574dd238226c154cdeec41 /src/backend/optimizer/plan/planner.c | |
| parent | ede7d8192ca3d1f731d34fb82fdcfc3308b4355f (diff) | |
Don't allow LIMIT/OFFSET clause within sub-selects to be pushed to workers.
Allowing sub-select containing LIMIT/OFFSET in workers can lead to
inconsistent results at the top-level as there is no guarantee that the
row order will be fully deterministic. The fix is to prohibit pushing
LIMIT/OFFSET within sub-selects to workers.
Reported-by: Andrew Fletcher
Bug: 15324
Author: Amit Kapila
Reviewed-by: Dilip Kumar
Backpatch-through: 9.6
Discussion: https://postgr.es/m/153417684333.10284.11356259990921828616@wrigleys.postgresql.org
Diffstat (limited to 'src/backend/optimizer/plan/planner.c')
| -rw-r--r-- | src/backend/optimizer/plan/planner.c | 3 |
1 files changed, 1 insertions, 2 deletions
diff --git a/src/backend/optimizer/plan/planner.c b/src/backend/optimizer/plan/planner.c index 1946f9ef968..a8a025cb853 100644 --- a/src/backend/optimizer/plan/planner.c +++ b/src/backend/optimizer/plan/planner.c @@ -121,7 +121,6 @@ static void preprocess_rowmarks(PlannerInfo *root); static double preprocess_limit(PlannerInfo *root, double tuple_fraction, int64 *offset_est, int64 *count_est); -static bool limit_needed(Query *parse); static void remove_useless_groupby_columns(PlannerInfo *root); static List *preprocess_groupclause(PlannerInfo *root, List *force); static List *extract_rollup_sets(List *groupingSets); @@ -2697,7 +2696,7 @@ preprocess_limit(PlannerInfo *root, double tuple_fraction, * a key distinction: here we need hard constants in OFFSET/LIMIT, whereas * in preprocess_limit it's good enough to consider estimated values. */ -static bool +bool limit_needed(Query *parse) { Node *node; |