Hi,
I stumbled across a minor issue in xlog.c:1030: the WAL_DEBUG code block
there passes rdata->data to the rm_desc() methode. However, that's only
the first XLogRecData struct, not the entire XLog record. So the
rm_desc() method effectively reports spurious data for any subsequent part.
Take a commit record with subxacts as an example: during XLogInsert,
Postgres reports the following:
LOG: INSERT @ 0/16F3270: prev 0/16F3234; xid 688; len 16: Transaction -
commit: 2012-10-11 09:31:17.790368-07; subxacts: 3214563816
Note that the xid in subxacts is way off. During recovery from WAL, the
record is logged correctly:
LOG: REDO @ 0/16F3270; LSN 0/16F329C: prev 0/16F3234; xid 688; len 16:
Transaction - commit: 2012-10-11 09:31:17.790368-07; subxacts: 689
Attached is a possible fix.
Regards
Markus Wanner
*** a/src/backend/access/transam/xlog.c
--- b/src/backend/access/transam/xlog.c
***************
*** 1033,1039 **** begin:;
#ifdef WAL_DEBUG
if (XLOG_DEBUG)
{
! StringInfoData buf;
initStringInfo(&buf);
appendStringInfo(&buf, "INSERT @ %X/%X: ",
--- 1033,1056 ----
#ifdef WAL_DEBUG
if (XLOG_DEBUG)
{
! StringInfoData buf;
! char *full_rec = palloc(write_len), *ins_ptr;
!
! /*
! * We need assemble the entire record once, to be able to dump it out
! * properly.
! */
! rdt = rdata;
! ins_ptr = full_rec;
! while (rdt)
! {
! if (rdt->data != NULL)
! {
! memcpy(ins_ptr, rdt->data, rdt->len);
! ins_ptr += rdt->len;
! }
! rdt = rdt->next;
! }
initStringInfo(&buf);
appendStringInfo(&buf, "INSERT @ %X/%X: ",
***************
*** 1042,1051 **** begin:;
if (rdata->data != NULL)
{
appendStringInfo(&buf, " - ");
! RmgrTable[rechdr->xl_rmid].rm_desc(&buf, rechdr->xl_info, rdata->data);
}
elog(LOG, "%s", buf.data);
pfree(buf.data);
}
#endif
--- 1059,1069 ----
if (rdata->data != NULL)
{
appendStringInfo(&buf, " - ");
! RmgrTable[rechdr->xl_rmid].rm_desc(&buf, rechdr->xl_info, full_rec);
}
elog(LOG, "%s", buf.data);
pfree(buf.data);
+ pfree(full_rec);
}
#endif
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