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Transaction IDs wrap around, per my proposal of 13-Aug-01. More

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documentation to come, but the code is all here.  initdb forced.
This commit is contained in:
Tom Lane
2001-08-26 16:56:03 +00:00
parent d1ee78f296
commit bc7d37a525
29 changed files with 617 additions and 171 deletions
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22
src/backend/access/transam/clog.c
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@ -13,7 +13,7 @@
* Portions Copyright (c) 1996-2001, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* $Header: /cvsroot/pgsql/src/backend/access/transam/clog.c,v 1.2 2001/08/25 23:24:39 tgl Exp $
* $Header: /cvsroot/pgsql/src/backend/access/transam/clog.c,v 1.3 2001/08/26 16:55:59 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -762,8 +762,12 @@ ExtendCLOG(TransactionId newestXact)
{
int pageno;
/* No work except at first XID of a page */
if (TransactionIdToPgIndex(newestXact) != 0)
/*
* No work except at first XID of a page. But beware: just after
* wraparound, the first XID of page zero is FirstNormalTransactionId.
*/
if (TransactionIdToPgIndex(newestXact) != 0 &&
!TransactionIdEquals(newestXact, FirstNormalTransactionId))
return;
pageno = TransactionIdToPage(newestXact);
@ -818,6 +822,18 @@ TruncateCLOG(TransactionId oldestXact)
S_LOCK(&(ClogCtl->control_lck));
restart:;
/*
* While we are holding the lock, make an important safety check:
* the planned cutoff point must be <= the current CLOG endpoint page.
* Otherwise we have already wrapped around, and proceeding with the
* truncation would risk removing the current CLOG segment.
*/
if (CLOGPagePrecedes(ClogCtl->latest_page_number, cutoffPage))
{
S_UNLOCK(&(ClogCtl->control_lck));
elog(LOG, "unable to truncate commit log: apparent wraparound");
return;
}
for (slotno = 0; slotno < NUM_CLOG_BUFFERS; slotno++)
{