Stop btree indexscans upon reaching nulls in either direction.
The existing scan-direction-sensitive tests were overly complex, and
failed to stop the scan in cases where it's perfectly legitimate to do so.
Per bug #6278 from Maksym Boguk.
Back-patch to 8.3, which is as far back as the patch applies easily.
Doesn't seem worth sweating over a relatively minor performance issue in
8.2 at this late date. (But note that this was a performance regression
from 8.1 and before, so 8.2 is being left as an outlier.)
Branch
------
REL8_4_STABLE
Details
-------
http://git.postgresql.org/pg/commitdiff/d23165bbc306005f687756a20d9af807d665a1f2
Modified Files
--------------
src/backend/access/nbtree/nbtutils.c | 107 +++++++++++++--------------------
1 files changed, 42 insertions(+), 65 deletions(-)