From 62e0ade9aa89c8f88ce506e1cb4be6e3697ee2d0 Mon Sep 17 00:00:00 2001 From: Teodor Sigaev Date: Tue, 2 Feb 2016 15:21:03 +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 ad39294875..ee3289ae8e 100644 --- a/src/backend/access/gist/gistscan.c +++ b/src/backend/access/gist/gistscan.c @@ -230,6 +230,10 @@ gistrescan(PG_FUNCTION_ARGS) { 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); @@ -285,8 +289,6 @@ gistrescan(PG_FUNCTION_ARGS) 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, @@ -301,6 +303,12 @@ gistrescan(PG_FUNCTION_ARGS) */ 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];