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Merge the various forms of transaction commit & abort records.

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Since 465883b0a two versions of commit records have existed. A compact
version that was used when no cache invalidations, smgr unlinks and
similar were needed, and a full version that could deal with all
that. Additionally the full version was embedded into twophase commit
records.

That resulted in a measurable reduction in the size of the logged WAL in
some workloads. But more recently additions like logical decoding, which
e.g. needs information about the database something was executed on,
made it applicable in fewer situations. The static split generally made
it hard to expand the commit record, because concerns over the size made
it hard to add anything to the compact version.

Additionally it's not particularly pretty to have twophase.c insert
RM_XACT records.

Rejigger things so that the commit and abort records only have one form
each, including the twophase equivalents. The presence of the various
optional (in the sense of not being in every record) pieces is indicated
by a bits in the 'xinfo' flag.  That flag previously was not included in
compact commit records. To prevent an increase in size due to its
presence, it's only included if necessary; signalled by a bit in the
xl_info bits available for xact.c, similar to heapam.c's
XLOG_HEAP_OPMASK/XLOG_HEAP_INIT_PAGE.

Twophase commit/aborts are now the same as their normal
counterparts. The original transaction's xid is included in an optional
data field.

This means that commit records generally are smaller, except in the case
of a transaction with subtransactions, but no other special cases; the
increase there is four bytes, which seems acceptable given that the more
common case of not having subtransactions shrank.  The savings are
especially measurable for twophase commits, which previously always used
the full version; but will in practice only infrequently have required
that.

The motivation for this work are not the space savings and and
deduplication though; it's that it makes it easier to extend commit
records with additional information. That's just a few lines of code
now; without impacting the common case where that information is not
needed.

Discussion: 20150220152150.GD4149@awork2.anarazel.de,
    235610.92468.qm%40web29004.mail.ird.yahoo.com

Reviewed-By: Heikki Linnakangas, Simon Riggs
This commit is contained in:
Andres Freund
2015-03-15 17:37:07 +01:00
parent a0f5954af1
commit 4f1b890b13
7 changed files with 752 additions and 511 deletions
Download Patch File Download Diff File Expand all files Collapse all files

245
src/backend/access/rmgrdesc/xactdesc.c
View File

@@ -14,53 +14,188 @@
*/
#include "postgres.h"
#include "access/transam.h"
#include "access/xact.h"
#include "catalog/catalog.h"
#include "storage/sinval.h"
#include "utils/timestamp.h"
/*
* Parse the WAL format of a xact commit and abort records into a easier to
* understand format.
*
* This routines are in xactdesc.c because they're accessed in backend (when
* replaying WAL) and frontend (pg_xlogdump) code. This file is the only xact
* specific one shared between both. They're complicated enough that
* duplication would be bothersome.
*/
void
ParseCommitRecord(uint8 info, xl_xact_commit *xlrec, xl_xact_parsed_commit *parsed)
{
char *data = ((char *) xlrec) + MinSizeOfXactCommit;
memset(parsed, 0, sizeof(*parsed));
parsed->xinfo = 0; /* default, if no XLOG_XACT_HAS_INFO is present */
parsed->xact_time = xlrec->xact_time;
if (info & XLOG_XACT_HAS_INFO)
{
xl_xact_xinfo *xl_xinfo = (xl_xact_xinfo *) data;
parsed->xinfo = xl_xinfo->xinfo;
data += sizeof(xl_xact_xinfo);
}
if (parsed->xinfo & XACT_XINFO_HAS_DBINFO)
{
xl_xact_dbinfo *xl_dbinfo = (xl_xact_dbinfo *) data;
parsed->dbId = xl_dbinfo->dbId;
parsed->tsId = xl_dbinfo->tsId;
data += sizeof(xl_xact_dbinfo);
}
if (parsed->xinfo & XACT_XINFO_HAS_SUBXACTS)
{
xl_xact_subxacts *xl_subxacts = (xl_xact_subxacts *) data;
parsed->nsubxacts = xl_subxacts->nsubxacts;
parsed->subxacts = xl_subxacts->subxacts;
data += MinSizeOfXactSubxacts;
data += parsed->nsubxacts * sizeof(TransactionId);
}
if (parsed->xinfo & XACT_XINFO_HAS_RELFILENODES)
{
xl_xact_relfilenodes *xl_relfilenodes = (xl_xact_relfilenodes *) data;
parsed->nrels = xl_relfilenodes->nrels;
parsed->xnodes = xl_relfilenodes->xnodes;
data += MinSizeOfXactRelfilenodes;
data += xl_relfilenodes->nrels * sizeof(RelFileNode);
}
if (parsed->xinfo & XACT_XINFO_HAS_INVALS)
{
xl_xact_invals *xl_invals = (xl_xact_invals *) data;
parsed->nmsgs = xl_invals->nmsgs;
parsed->msgs = xl_invals->msgs;
data += MinSizeOfXactInvals;
data += xl_invals->nmsgs * sizeof(SharedInvalidationMessage);
}
if (parsed->xinfo & XACT_XINFO_HAS_TWOPHASE)
{
xl_xact_twophase *xl_twophase = (xl_xact_twophase *) data;
parsed->twophase_xid = xl_twophase->xid;
data += sizeof(xl_xact_twophase);
}
}
void
ParseAbortRecord(uint8 info, xl_xact_abort *xlrec, xl_xact_parsed_abort *parsed)
{
char *data = ((char *) xlrec) + MinSizeOfXactAbort;
memset(parsed, 0, sizeof(*parsed));
parsed->xinfo = 0; /* default, if no XLOG_XACT_HAS_INFO is present */
parsed->xact_time = xlrec->xact_time;
if (info & XLOG_XACT_HAS_INFO)
{
xl_xact_xinfo *xl_xinfo = (xl_xact_xinfo *) data;
parsed->xinfo = xl_xinfo->xinfo;
data += sizeof(xl_xact_xinfo);
}
if (parsed->xinfo & XACT_XINFO_HAS_SUBXACTS)
{
xl_xact_subxacts *xl_subxacts = (xl_xact_subxacts *) data;
parsed->nsubxacts = xl_subxacts->nsubxacts;
parsed->subxacts = xl_subxacts->subxacts;
data += MinSizeOfXactSubxacts;
data += parsed->nsubxacts * sizeof(TransactionId);
}
if (parsed->xinfo & XACT_XINFO_HAS_RELFILENODES)
{
xl_xact_relfilenodes *xl_relfilenodes = (xl_xact_relfilenodes *) data;
parsed->nrels = xl_relfilenodes->nrels;
parsed->xnodes = xl_relfilenodes->xnodes;
data += MinSizeOfXactRelfilenodes;
data += xl_relfilenodes->nrels * sizeof(RelFileNode);
}
if (parsed->xinfo & XACT_XINFO_HAS_TWOPHASE)
{
xl_xact_twophase *xl_twophase = (xl_xact_twophase *) data;
parsed->twophase_xid = xl_twophase->xid;
data += sizeof(xl_xact_twophase);
}
}
static void
xact_desc_commit(StringInfo buf, xl_xact_commit *xlrec)
xact_desc_commit(StringInfo buf, uint8 info, xl_xact_commit *xlrec)
{
xl_xact_parsed_commit parsed;
int i;
TransactionId *subxacts;
subxacts = (TransactionId *) &xlrec->xnodes[xlrec->nrels];
ParseCommitRecord(info, xlrec, &parsed);
/* If this is a prepared xact, show the xid of the original xact */
if (TransactionIdIsValid(parsed.twophase_xid))
appendStringInfo(buf, "%u: ", parsed.twophase_xid);
appendStringInfoString(buf, timestamptz_to_str(xlrec->xact_time));
if (xlrec->nrels > 0)
if (parsed.nrels > 0)
{
appendStringInfoString(buf, "; rels:");
for (i = 0; i < xlrec->nrels; i++)
for (i = 0; i < parsed.nrels; i++)
{
char *path = relpathperm(xlrec->xnodes[i], MAIN_FORKNUM);
char *path = relpathperm(parsed.xnodes[i], MAIN_FORKNUM);
appendStringInfo(buf, " %s", path);
pfree(path);
}
}
if (xlrec->nsubxacts > 0)
if (parsed.nsubxacts > 0)
{
appendStringInfoString(buf, "; subxacts:");
for (i = 0; i < xlrec->nsubxacts; i++)
appendStringInfo(buf, " %u", subxacts[i]);
for (i = 0; i < parsed.nsubxacts; i++)
appendStringInfo(buf, " %u", parsed.subxacts[i]);
}
if (xlrec->nmsgs > 0)
if (parsed.nmsgs > 0)
{
SharedInvalidationMessage *msgs;
msgs = (SharedInvalidationMessage *) &subxacts[xlrec->nsubxacts];
if (XactCompletionRelcacheInitFileInval(xlrec->xinfo))
if (XactCompletionRelcacheInitFileInval(parsed.xinfo))
appendStringInfo(buf, "; relcache init file inval dbid %u tsid %u",
xlrec->dbId, xlrec->tsId);
parsed.dbId, parsed.tsId);
appendStringInfoString(buf, "; inval msgs:");
for (i = 0; i < xlrec->nmsgs; i++)
for (i = 0; i < parsed.nmsgs; i++)
{
SharedInvalidationMessage *msg = &msgs[i];
SharedInvalidationMessage *msg = &parsed.msgs[i];
if (msg->id >= 0)
appendStringInfo(buf, " catcache %d", msg->id);
@@ -80,48 +215,41 @@ xact_desc_commit(StringInfo buf, xl_xact_commit *xlrec)
appendStringInfo(buf, " unknown id %d", msg->id);
}
}
if (XactCompletionForceSyncCommit(parsed.xinfo))
appendStringInfo(buf, "; sync");
}
static void
xact_desc_commit_compact(StringInfo buf, xl_xact_commit_compact *xlrec)
xact_desc_abort(StringInfo buf, uint8 info, xl_xact_abort *xlrec)
{
xl_xact_parsed_abort parsed;
int i;
appendStringInfoString(buf, timestamptz_to_str(xlrec->xact_time));
ParseAbortRecord(info, xlrec, &parsed);
if (xlrec->nsubxacts > 0)
{
appendStringInfoString(buf, "; subxacts:");
for (i = 0; i < xlrec->nsubxacts; i++)
appendStringInfo(buf, " %u", xlrec->subxacts[i]);
}
}
static void
xact_desc_abort(StringInfo buf, xl_xact_abort *xlrec)
{
int i;
/* If this is a prepared xact, show the xid of the original xact */
if (TransactionIdIsValid(parsed.twophase_xid))
appendStringInfo(buf, "%u: ", parsed.twophase_xid);
appendStringInfoString(buf, timestamptz_to_str(xlrec->xact_time));
if (xlrec->nrels > 0)
if (parsed.nrels > 0)
{
appendStringInfoString(buf, "; rels:");
for (i = 0; i < xlrec->nrels; i++)
for (i = 0; i < parsed.nrels; i++)
{
char *path = relpathperm(xlrec->xnodes[i], MAIN_FORKNUM);
char *path = relpathperm(parsed.xnodes[i], MAIN_FORKNUM);
appendStringInfo(buf, " %s", path);
pfree(path);
}
}
if (xlrec->nsubxacts > 0)
{
TransactionId *xacts = (TransactionId *)
&xlrec->xnodes[xlrec->nrels];
if (parsed.nsubxacts > 0)
{
appendStringInfoString(buf, "; subxacts:");
for (i = 0; i < xlrec->nsubxacts; i++)
appendStringInfo(buf, " %u", xacts[i]);
for (i = 0; i < parsed.nsubxacts; i++)
appendStringInfo(buf, " %u", parsed.subxacts[i]);
}
}
@@ -140,39 +268,19 @@ void
xact_desc(StringInfo buf, XLogReaderState *record)
{
char *rec = XLogRecGetData(record);
uint8 info = XLogRecGetInfo(record) & ~XLR_INFO_MASK;
uint8 info = XLogRecGetInfo(record) & XLOG_XACT_OPMASK;
if (info == XLOG_XACT_COMMIT_COMPACT)
{
xl_xact_commit_compact *xlrec = (xl_xact_commit_compact *) rec;
xact_desc_commit_compact(buf, xlrec);
}
else if (info == XLOG_XACT_COMMIT)
if (info == XLOG_XACT_COMMIT || info == XLOG_XACT_COMMIT_PREPARED)
{
xl_xact_commit *xlrec = (xl_xact_commit *) rec;
xact_desc_commit(buf, xlrec);
xact_desc_commit(buf, XLogRecGetInfo(record), xlrec);
}
else if (info == XLOG_XACT_ABORT)
else if (info == XLOG_XACT_ABORT || info == XLOG_XACT_ABORT_PREPARED)
{
xl_xact_abort *xlrec = (xl_xact_abort *) rec;
xact_desc_abort(buf, xlrec);
}
else if (info == XLOG_XACT_COMMIT_PREPARED)
{
xl_xact_commit_prepared *xlrec = (xl_xact_commit_prepared *) rec;
appendStringInfo(buf, "%u: ", xlrec->xid);
xact_desc_commit(buf, &xlrec->crec);
}
else if (info == XLOG_XACT_ABORT_PREPARED)
{
xl_xact_abort_prepared *xlrec = (xl_xact_abort_prepared *) rec;
appendStringInfo(buf, "%u: ", xlrec->xid);
xact_desc_abort(buf, &xlrec->arec);
xact_desc_abort(buf, XLogRecGetInfo(record), xlrec);
}
else if (info == XLOG_XACT_ASSIGNMENT)
{
@@ -193,7 +301,7 @@ xact_identify(uint8 info)
{
const char *id = NULL;
switch (info & ~XLR_INFO_MASK)
switch (info & XLOG_XACT_OPMASK)
{
case XLOG_XACT_COMMIT:
id = "COMMIT";
@@ -213,9 +321,6 @@ xact_identify(uint8 info)
case XLOG_XACT_ASSIGNMENT:
id = "ASSIGNMENT";
break;
case XLOG_XACT_COMMIT_COMPACT:
id = "COMMIT_COMPACT";
break;
}
return id;