More btree fixes from Massimo Dal Zotto <dz@cs.unitn.it>

scrappy · scrappy · commit 025709640c48 · 1996-10-30T06:06:50.000Z
Fixes:

I found another bug in btree index.  Looking at the code it seems that NULL
keys are never used to build or scan a btree index (see the explain commands
in the example).  However this is not the case when a null key is retrieved
in an outer loop of a join select and used in an index scan of an inner loop.
This bug causes at least three kinds of problems:

1)  the backend crashes when it tries to compare a text string with a null.

2)  it is not possible to find tuples with null keys in a join.

3)  null is considered equal to 0 when the datum is passed by value, see
    the last query.
diff --git a/src/backend/access/common/heapvalid.c b/src/backend/access/common/heapvalid.c
@@ -7,7 +7,7 @@
  *
  *
  * IDENTIFICATION
- *    $Header: /cvsroot/pgsql/src/backend/access/common/Attic/heapvalid.c,v 1.1.1.1 1996/07/09 06:21:09 scrappy Exp $
+ *    $Header: /cvsroot/pgsql/src/backend/access/common/Attic/heapvalid.c,v 1.1.1.1.2.1 1996/10/30 06:06:36 scrappy Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -54,6 +54,10 @@ heap_keytest(HeapTuple t,
 	    /* XXX eventually should check if SK_ISNULL */
 	    return false;
 	
+	if (keys->sk_flags & SK_ISNULL) {
+	    return (false);
+	}
+
 	if (keys->sk_flags & SK_COMMUTE)
 	    test = (long) FMGR_PTR2(keys->sk_func, keys->sk_procedure,
 				    keys->sk_argument, atp);
diff --git a/src/backend/access/common/indexvalid.c b/src/backend/access/common/indexvalid.c
@@ -7,7 +7,7 @@
  *
  *
  * IDENTIFICATION
- *    $Header: /cvsroot/pgsql/src/backend/access/common/Attic/indexvalid.c,v 1.1.1.1 1996/07/09 06:21:09 scrappy Exp $
+ *    $Header: /cvsroot/pgsql/src/backend/access/common/Attic/indexvalid.c,v 1.1.1.1.2.1 1996/10/30 06:06:34 scrappy Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -61,6 +61,10 @@ index_keytest(IndexTuple tuple,
 	    return (false);
 	}
 	
+	if (key[0].sk_flags & SK_ISNULL) {
+	    return (false);
+	}
+
 	if (key[0].sk_flags & SK_COMMUTE) {
 	    test = (int) (*(key[0].sk_func))
 		(DatumGetPointer(key[0].sk_argument),
diff --git a/src/backend/access/nbtree/nbtsearch.c b/src/backend/access/nbtree/nbtsearch.c
@@ -7,7 +7,7 @@
  *
  *
  * IDENTIFICATION
- *    $Header: /cvsroot/pgsql/src/backend/access/nbtree/nbtsearch.c,v 1.2 1996/07/30 07:56:02 scrappy Exp $
+ *    $Header: /cvsroot/pgsql/src/backend/access/nbtree/nbtsearch.c,v 1.2.2.1 1996/10/30 06:06:40 scrappy Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -248,6 +248,18 @@ _bt_skeycmp(Relation rel,
 				  &isNull);
 	keyDatum  = entry->sk_argument;
 	
+	/*
+	 * This may happen in a nested loop if an attribute used
+	 * as scan key is null.			DZ 29-10-1996
+	 */
+	if ((entry->sk_flags & SK_ISNULL) || (isNull)) {
+	    if ((entry->sk_flags & SK_ISNULL) && (isNull)) {
+		return (true);
+	    } else {
+		return (false);
+	    }
+	}
+
 	compare = _bt_invokestrat(rel, i, strat, keyDatum, attrDatum);
 	if (!compare)
 	    return (false);
@@ -490,6 +502,19 @@ _bt_compare(Relation rel,
 	entry = &scankey[i - 1];
 	attno = entry->sk_attno;
 	datum = index_getattr(itup, attno, itupdesc, &null);
+
+	/*
+	 * This may happen in a nested loop if an attribute used
+	 * as scan key is null.			DZ 29-10-1996
+	 */
+	if ((entry->sk_flags & SK_ISNULL) || (null)) {
+	    if ((entry->sk_flags & SK_ISNULL) && (null)) {
+		return (0);
+	    } else {
+		return (null ? +1 : -1);
+	    }
+	}
+
 	tmpres = (long) FMGR_PTR2(entry->sk_func, entry->sk_procedure,
 				  entry->sk_argument, datum);
 	result = tmpres;
@@ -630,7 +655,7 @@ _bt_first(IndexScanDesc scan, ScanDirection dir)
      *	       hardwired attno == 1.
      */
     proc = index_getprocid(rel, 1, BTORDER_PROC);
-    ScanKeyEntryInitialize(&skdata, 0x0, 1, proc,
+    ScanKeyEntryInitialize(&skdata, so->keyData[0].sk_flags, 1, proc,
 			   so->keyData[0].sk_argument);
     
     stack = _bt_search(rel, 1, &skdata, &buf);
diff --git a/src/backend/executor/nodeIndexscan.c b/src/backend/executor/nodeIndexscan.c
@@ -7,7 +7,7 @@
  *
  *
  * IDENTIFICATION
- *    $Header: /cvsroot/pgsql/src/backend/executor/nodeIndexscan.c,v 1.1.1.1 1996/07/09 06:21:26 scrappy Exp $
+ *    $Header: /cvsroot/pgsql/src/backend/executor/nodeIndexscan.c,v 1.1.1.1.2.1 1996/10/30 06:06:50 scrappy Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -273,6 +273,11 @@ ExecIndexReScan(IndexScan *node, ExprContext *exprCtxt, Plan* parent)
 		scanvalue = (Datum)
 		    ExecEvalExpr(scanexpr, exprCtxt, &isNull, &isDone);
 		scan_keys[j].sk_argument = scanvalue;
+		if (isNull) {
+		    scan_keys[j].sk_flags |= SK_ISNULL;
+		} else {
+		    scan_keys[j].sk_flags &= ~SK_ISNULL;
+		}
 	    }
 	}
     } 

Original file line number	Diff line number	Diff line change
`@@ -7,7 +7,7 @@`
`7`	`7`	`*`
`8`	`8`	`*`
`9`	`9`	`* IDENTIFICATION`
`10`		`- * $Header: /cvsroot/pgsql/src/backend/access/common/Attic/heapvalid.c,v 1.1.1.1 1996/07/09 06:21:09 scrappy Exp $`
	`10`	`+ * $Header: /cvsroot/pgsql/src/backend/access/common/Attic/heapvalid.c,v 1.1.1.1.2.1 1996/10/30 06:06:36 scrappy Exp $`
`11`	`11`	`*`
`12`	`12`	`*-------------------------------------------------------------------------`
`13`	`13`	`*/`
`@@ -54,6 +54,10 @@ heap_keytest(HeapTuple t,`
`54`	`54`	`/* XXX eventually should check if SK_ISNULL */`
`55`	`55`	`return false;`
`56`	`56`
	`57`	`+ if (keys->sk_flags & SK_ISNULL) {`
	`58`	`+ return (false);`
	`59`	`+ }`
	`60`	`+`
`57`	`61`	`if (keys->sk_flags & SK_COMMUTE)`
`58`	`62`	`test = (long) FMGR_PTR2(keys->sk_func, keys->sk_procedure,`
`59`	`63`	`keys->sk_argument, atp);`