From f25d07d99f4acf136baed4ef29ea97faad7337db Mon Sep 17 00:00:00 2001 From: Teodor Sigaev Date: Tue, 2 Feb 2016 15:20:33 +0300 Subject: [PATCH] Fix lossy KNN GiST when ordering operator returns non-float8 value. KNN GiST with recheck flag should return to executor the same type as ordering operator, GiST detects this type by looking to return type of function which implements ordering operator. But occasionally detecting code works after replacing ordering operator function to distance support function. Distance support function always returns float8, so, detecting code get float8 instead of actual return type of ordering operator. Built-in opclasses don't have ordering operator which doesn't return non-float8 value, so, tests are impossible here, at least now. Backpatch to 9.5 where lozzy KNN was introduced. Author: Alexander Korotkov Report by: Artur Zakirov --- src/backend/access/gist/gistscan.c | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-) diff --git a/src/backend/access/gist/gistscan.c b/src/backend/access/gist/gistscan.c index 31758a1c8f..328e54b85e 100644 --- a/src/backend/access/gist/gistscan.c +++ b/src/backend/access/gist/gistscan.c @@ -229,6 +229,10 @@ gistrescan(IndexScanDesc scan, ScanKey key, int nkeys, { ScanKey skey = scan->keyData + i; + /* + * Copy consistent support function to ScanKey structure + * instead of function implementing filtering operator. + */ fmgr_info_copy(&(skey->sk_func), &(so->giststate->consistentFn[skey->sk_attno - 1]), so->giststate->scanCxt); @@ -284,8 +288,6 @@ gistrescan(IndexScanDesc scan, ScanKey key, int nkeys, GIST_DISTANCE_PROC, skey->sk_attno, RelationGetRelationName(scan->indexRelation)); - fmgr_info_copy(&(skey->sk_func), finfo, so->giststate->scanCxt); - /* * Look up the datatype returned by the original ordering * operator. GiST always uses a float8 for the distance function, @@ -300,6 +302,12 @@ gistrescan(IndexScanDesc scan, ScanKey key, int nkeys, */ so->orderByTypes[i] = get_func_rettype(skey->sk_func.fn_oid); + /* + * Copy distance support function to ScanKey structure + * instead of function implementing ordering operator. + */ + fmgr_info_copy(&(skey->sk_func), finfo, so->giststate->scanCxt); + /* Restore prior fn_extra pointers, if not first time */ if (!first_time) skey->sk_func.fn_extra = fn_extras[i];