Fix no-longer-correct bit-pushing in TransactionIdSetStatus, per Alvaro.

diff --git a/src/backend/access/transam/clog.c b/src/backend/access/transam/clog.c
index 54514a24e71ccd727374c8c5f5afe46f0db0e07c..6de10d16a129ded8741837e56ba18344aedee6f6 100644 (file)
--- a/src/backend/access/transam/clog.c
+++ b/src/backend/access/transam/clog.c
@@ -13,7 +13,7 @@
  * Portions Copyright (c) 1996-2003, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/backend/access/transam/clog.c,v 1.21 2004/07/01 00:49:42 tgl Exp $
+ * $PostgreSQL: pgsql/src/backend/access/transam/clog.c,v 1.22 2004/07/03 02:55:56 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -92,6 +92,7 @@ TransactionIdSetStatus(TransactionId xid, XidStatus status)
        int                     byteno = TransactionIdToByte(xid);
        int                     bshift = TransactionIdToBIndex(xid) * CLOG_BITS_PER_XACT;
        char       *byteptr;
+       char            byteval;
 
        Assert(status == TRANSACTION_STATUS_COMMITTED ||
                   status == TRANSACTION_STATUS_ABORTED ||
@@ -107,7 +108,11 @@ TransactionIdSetStatus(TransactionId xid, XidStatus status)
                   ((*byteptr >> bshift) & CLOG_XACT_BITMASK) == TRANSACTION_STATUS_SUB_COMMITTED ||
                   ((*byteptr >> bshift) & CLOG_XACT_BITMASK) == status);
 
-       *byteptr |= (status << bshift);
+       /* note this assumes exclusive access to the clog page */
+       byteval = *byteptr;
+       byteval &= ~(((1 << CLOG_BITS_PER_XACT) - 1) << bshift);
+       byteval |= (status << bshift);
+       *byteptr = byteval;
 
        /* ...->page_status[slotno] = SLRU_PAGE_DIRTY; already done */