postgres.git / summary / log / commit / refs

commit    27048980f503da22dcd289ec8342b7021c8e73e6
Author:   Tom Lane <tgl@sss.pgh.pa.us>
Date:     Tue Jul 22 17:30:01 2014 +0000
First released in: 9.5.0, 9.3.6, 9.4.0

    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.


 src/backend/optimizer/plan/planner.c | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/src/backend/optimizer/plan/planner.c b/src/backend/optimizer/plan/planner.c
index f2c9c99b7f6..e1480cda247 100644
--- a/src/backend/optimizer/plan/planner.c
+++ b/src/backend/optimizer/plan/planner.c
@@ -2335,7 +2335,7 @@ 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
@@ -2496,9 +2496,8 @@ 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


[parent: 27cef0a56111]