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| author | Peter Geoghegan <pg@bowt.ie> | 2019-11-12 13:08:41 -0800 |
|---|---|---|
| committer | Peter Geoghegan <pg@bowt.ie> | 2019-11-12 13:08:41 -0800 |
| commit | 1f55ebae27225111d0a5c4d89d7e77d917357ff4 (patch) | |
| tree | 2baf8563185a75129b01d773eca7123a64523fd4 /src | |
| parent | dcb7d3cafa3197c5425c129ba0dc5eddd23c0532 (diff) | |
| download | postgresql-1f55ebae27225111d0a5c4d89d7e77d917357ff4.tar.gz postgresql-1f55ebae27225111d0a5c4d89d7e77d917357ff4.zip | |
Make _bt_keep_natts_fast() use datum_image_eq().
An upcoming patch that adds deduplication to the nbtree AM will rely on
_bt_keep_natts_fast() understanding that differences in TOAST input
state can never affect its answer. In particular, two opclass-equal
datums (with opclasses deemed safe for deduplication) should never be
treated as unequal by _bt_keep_natts_fast() due to TOAST input
differences.
This also seems like a good idea on general principle. nbtsplitloc.c
will now occasionally make better decisions about where to split a leaf
page. The behavior of _bt_keep_natts_fast() is now somewhat closer to
the behavior of _bt_keep_natts().
Discussion: https://postgr.es/m/CAH2-Wzn3Ee49Gmxb7V1VJ3-AC8fWn-Fr8pfWQebHe8rYRxt5OQ@mail.gmail.com
Diffstat (limited to 'src')
| -rw-r--r-- | src/backend/access/nbtree/nbtutils.c | 6 |
1 files changed, 2 insertions, 4 deletions
diff --git a/src/backend/access/nbtree/nbtutils.c b/src/backend/access/nbtree/nbtutils.c index 6a3008dd48d..7669a1a66f5 100644 --- a/src/backend/access/nbtree/nbtutils.c +++ b/src/backend/access/nbtree/nbtutils.c @@ -2303,9 +2303,7 @@ _bt_keep_natts(Relation rel, IndexTuple lastleft, IndexTuple firstright, * The approach taken here usually provides the same answer as _bt_keep_natts * will (for the same pair of tuples from a heapkeyspace index), since the * majority of btree opclasses can never indicate that two datums are equal - * unless they're bitwise equal (once detoasted). Similarly, result may - * differ from the _bt_keep_natts result when either tuple has TOASTed datums, - * though this is barely possible in practice. + * unless they're bitwise equal after detoasting. * * These issues must be acceptable to callers, typically because they're only * concerned about making suffix truncation as effective as possible without @@ -2337,7 +2335,7 @@ _bt_keep_natts_fast(Relation rel, IndexTuple lastleft, IndexTuple firstright) break; if (!isNull1 && - !datumIsEqual(datum1, datum2, att->attbyval, att->attlen)) + !datum_image_eq(datum1, datum2, att->attbyval, att->attlen)) break; keepnatts++; |