From: Teodor Sigaev <teodor@sigaev.ru>
Date: Fri, 17 Oct 2008 17:02:42 +0000 (+0000)
Subject: During repeated rescan of GiST index it's possible that scan key
X-Git-Url: http://waps.l3s.uni-hannover.de/gitweb/?a=commitdiff_plain;h=6345c504f4ad6dbc0b62b414193be29efaf000bc;p=users%2Fbernd%2Fpostgres.git

During repeated rescan of GiST index it's possible that scan key
is NULL but SK_SEARCHNULL is not set. Add checking IS NULL of keys
to set during key initialization. If key is NULL and SK_SEARCHNULL is not
set then nothnig can be satisfied.
With assert-enabled compilation that causes coredump.

Bug was introduced in 8.3 by support of IS NULL index scan.
---

diff --git a/src/backend/access/gist/gistget.c b/src/backend/access/gist/gistget.c
index b5f969048a..202f76bb85 100644
--- a/src/backend/access/gist/gistget.c
+++ b/src/backend/access/gist/gistget.c
@@ -127,6 +127,9 @@ gistnext(IndexScanDesc scan, ScanDirection dir, ItemPointer tids,
 
 	so = (GISTScanOpaque) scan->opaque;
 
+	if ( so->qual_ok == false )
+		return 0;
+
 	if (ItemPointerIsValid(&so->curpos) == false)
 	{
 		/* Being asked to fetch the first entry, so start at the root */
diff --git a/src/backend/access/gist/gistscan.c b/src/backend/access/gist/gistscan.c
index a6d5ffbd27..dc9a6d0e94 100644
--- a/src/backend/access/gist/gistscan.c
+++ b/src/backend/access/gist/gistscan.c
@@ -96,9 +96,19 @@ gistrescan(PG_FUNCTION_ARGS)
 		 * function in the form of its strategy number, which is available
 		 * from the sk_strategy field, and its subtype from the sk_subtype
 		 * field.
+		 *
+		 * Next, if any of keys is a NULL and that key is not marked with
+		 * SK_SEARCHNULL then nothing can be found.
 		 */
-		for (i = 0; i < scan->numberOfKeys; i++)
+		so->qual_ok = true;
+		for (i = 0; i < scan->numberOfKeys; i++) {
 			scan->keyData[i].sk_func = so->giststate->consistentFn[scan->keyData[i].sk_attno - 1];
+
+			if ( scan->keyData[i].sk_flags & SK_ISNULL ) {
+				if ( (scan->keyData[i].sk_flags & SK_SEARCHNULL) == 0 )
+					so->qual_ok = false;
+			}
+		}
 	}
 
 	PG_RETURN_VOID();
diff --git a/src/include/access/gist_private.h b/src/include/access/gist_private.h
index 8f7ca0c5be..e892279bac 100644
--- a/src/include/access/gist_private.h
+++ b/src/include/access/gist_private.h
@@ -69,6 +69,7 @@ typedef struct GISTScanOpaqueData
 	GISTSearchStack *stack;
 	GISTSearchStack *markstk;
 	uint16		flags;
+	bool        qual_ok;        /* false if qual can never be satisfied */
 	GISTSTATE  *giststate;
 	MemoryContext tempCxt;
 	Buffer		curbuf;