Re: HeapTuple header changes cause core dumps in CVS tip

On Mon, 15 Jul 2002 16:46:44 -0400, Tom Lane <tgl@sss.pgh.pa.us>
wrote:
>regression=# update foo set f1 = 'qq';
>server closed the connection unexpectedly

Same with DELETE FROM foo;

>I am not sure if this is a bug introduced by the patch, or if it's
>exposed a previously lurking bug.

I suspect the former :-(

>It seems that the HEAP_MOVED bits
>should be cleared before re-using cmax for something else, but I have
>not dug through the old logic to see how it was done before.

AFAICS from a quick look at tqual it didn't matter before.  Once the
vacuum transaction had committed, on the next access to the tuple
MOVED_IN caused XMIN_COMMITTED to be set, and after that the MOVED
bits were never looked at again.  MOVED_OFF is not an issue.

I'll take a closer look at tqual and the vacuum source code tomorrow.
For now the attached patch cures both symptoms (UPDATE and DELETE) and
passes all regression tests.  A regression test for this case will
follow.

Servus
 Manfred
diff -ruN ../base/src/backend/access/heap/heapam.c src/backend/access/heap/heapam.c
--- ../base/src/backend/access/heap/heapam.c    2002-07-15 22:22:28.000000000 +0200
+++ src/backend/access/heap/heapam.c    2002-07-16 00:16:59.000000000 +0200
@@ -1123,11 +1123,11 @@
             CheckMaxObjectId(HeapTupleGetOid(tup));
     }

+    tup->t_data->t_infomask &= ~(HEAP_XACT_MASK);
     HeapTupleHeaderSetXmin(tup->t_data, GetCurrentTransactionId());
     HeapTupleHeaderSetCmin(tup->t_data, cid);
     HeapTupleHeaderSetXmaxInvalid(tup->t_data);
-    HeapTupleHeaderSetCmax(tup->t_data, FirstCommandId);
-    tup->t_data->t_infomask &= ~(HEAP_XACT_MASK);
+    /* HeapTupleHeaderSetCmax(tup->t_data, FirstCommandId); */
     tup->t_data->t_infomask |= HEAP_XMAX_INVALID;
     tup->t_tableOid = relation->rd_id;

@@ -1321,7 +1321,7 @@

     START_CRIT_SECTION();
     /* store transaction information of xact deleting the tuple */
-    tp.t_data->t_infomask &= ~(HEAP_XMAX_COMMITTED |
+    tp.t_data->t_infomask &= ~(HEAP_XMAX_COMMITTED | HEAP_MOVED |
                              HEAP_XMAX_INVALID | HEAP_MARKED_FOR_UPDATE);
     HeapTupleHeaderSetXmax(tp.t_data, GetCurrentTransactionId());
     HeapTupleHeaderSetCmax(tp.t_data, cid);
@@ -1554,7 +1554,7 @@
         _locked_tuple_.tid = oldtup.t_self;
         XactPushRollback(_heap_unlock_tuple, (void *) &_locked_tuple_);

-        oldtup.t_data->t_infomask &= ~(HEAP_XMAX_COMMITTED |
+        oldtup.t_data->t_infomask &= ~(HEAP_XMAX_COMMITTED | HEAP_MOVED |
                                        HEAP_XMAX_INVALID |
                                        HEAP_MARKED_FOR_UPDATE);
         oldtup.t_data->t_infomask |= HEAP_XMAX_UNLOGGED;
@@ -1645,7 +1645,7 @@
     }
     else
     {
-        oldtup.t_data->t_infomask &= ~(HEAP_XMAX_COMMITTED |
+        oldtup.t_data->t_infomask &= ~(HEAP_XMAX_COMMITTED | HEAP_MOVED |
                                        HEAP_XMAX_INVALID |
                                        HEAP_MARKED_FOR_UPDATE);
         HeapTupleHeaderSetXmax(oldtup.t_data, GetCurrentTransactionId());
@@ -1816,7 +1816,7 @@
     ((PageHeader) BufferGetPage(*buffer))->pd_sui = ThisStartUpID;

     /* store transaction information of xact marking the tuple */
-    tuple->t_data->t_infomask &= ~(HEAP_XMAX_COMMITTED | HEAP_XMAX_INVALID);
+    tuple->t_data->t_infomask &= ~(HEAP_XMAX_COMMITTED | HEAP_XMAX_INVALID | HEAP_MOVED);
     tuple->t_data->t_infomask |= HEAP_MARKED_FOR_UPDATE;
     HeapTupleHeaderSetXmax(tuple->t_data, GetCurrentTransactionId());
     HeapTupleHeaderSetCmax(tuple->t_data, cid);
@@ -2147,7 +2147,7 @@

     if (redo)
     {
-        htup->t_infomask &= ~(HEAP_XMAX_COMMITTED |
+        htup->t_infomask &= ~(HEAP_XMAX_COMMITTED | HEAP_MOVED |
                               HEAP_XMAX_INVALID | HEAP_MARKED_FOR_UPDATE);
         HeapTupleHeaderSetXmax(htup, record->xl_xid);
         HeapTupleHeaderSetCmax(htup, FirstCommandId);
@@ -2320,7 +2320,7 @@
         }
         else
         {
-            htup->t_infomask &= ~(HEAP_XMAX_COMMITTED |
+            htup->t_infomask &= ~(HEAP_XMAX_COMMITTED | HEAP_MOVED |
                              HEAP_XMAX_INVALID | HEAP_MARKED_FOR_UPDATE);
             HeapTupleHeaderSetXmax(htup, record->xl_xid);
             HeapTupleHeaderSetCmax(htup, FirstCommandId);