From: Tom Lane <tgl@sss.pgh.pa.us> Date: Tue, 22 Jul 2014 17:30:01 +0000 (-0400) Subject: Re-enable error for "SELECT ... OFFSET -1". X-Git-Tag: REL9_4_BETA3~146 X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=30d6a9858cd8389e59d652d9919761dc095326c5;p=postgresql Re-enable error for "SELECT ... OFFSET -1". The executor has thrown errors for negative OFFSET values since 8.4 (see commit bfce56eea45b1369b7bb2150a150d1ac109f5073), but in a moment of brain fade I taught the planner that OFFSET with a constant negative value was a no-op (commit 1a1832eb085e5bca198735e5d0e766a3cb61b8fc). Reinstate the former behavior by only discarding OFFSET with a value of exactly 0. In passing, adjust a planner comment that referenced the ancient behavior. Back-patch to 9.3 where the mistake was introduced. --- diff --git a/src/backend/optimizer/plan/planner.c b/src/backend/optimizer/plan/planner.c index 0f1e2e4680..8e3a9068f1 100644 --- a/src/backend/optimizer/plan/planner.c +++ b/src/backend/optimizer/plan/planner.c @@ -2334,7 +2334,7 @@ preprocess_limit(PlannerInfo *root, double tuple_fraction, { *offset_est = DatumGetInt64(((Const *) est)->constvalue); if (*offset_est < 0) - *offset_est = 0; /* less than 0 is same as 0 */ + *offset_est = 0; /* treat as not present */ } } else @@ -2495,9 +2495,8 @@ limit_needed(Query *parse) { int64 offset = DatumGetInt64(((Const *) node)->constvalue); - /* Executor would treat less-than-zero same as zero */ - if (offset > 0) - return true; /* OFFSET with a positive value */ + if (offset != 0) + return true; /* OFFSET with a nonzero value */ } } else