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Commit8463be0

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Improve the performance of relation deletes during recovery.
When multiple relations are deleted at the same transaction,the files of those relations are deleted by one call to smgrdounlinkall(),which leads to scan whole shared_buffers only one time. OTOH,previously, during recovery, smgrdounlink() (not smgrdounlinkall()) wascalled for each file to delete, which led to scan shared_buffersmultiple times. Obviously this could cause to increase the WAL replaytime very much especially when shared_buffers was huge.To alleviate this situation, this commit changes the recovery so thatit also calls smgrdounlinkall() only one time to delete multiplerelation files.This is just fix for oversight of commit279628a, not new feature.So, per discussion on pgsql-hackers, we concluded to backpatch thisto all supported versions.Author: Fujii MasaoReviewed-by: Michael Paquier, Andres Freund, Thomas Munro, Kyotaro Horiguchi, Takayuki TsunakawaDiscussion:https://postgr.es/m/CAHGQGwHVQkdfDqtvGVkty+19cQakAydXn1etGND3X0PHbZ3+6w@mail.gmail.com
1 parentc2c69d4 commit8463be0

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4 files changed

+44
-29
lines changed

4 files changed

+44
-29
lines changed

‎src/backend/access/transam/twophase.c

Lines changed: 2 additions & 7 deletions
Original file line numberDiff line numberDiff line change
@@ -1390,7 +1390,6 @@ FinishPreparedTransaction(const char *gid, bool isCommit)
13901390
RelFileNode*delrels;
13911391
intndelrels;
13921392
SharedInvalidationMessage*invalmsgs;
1393-
inti;
13941393

13951394
/*
13961395
* Validate the GID, and lock the GXACT to ensure that two backends do not
@@ -1482,13 +1481,9 @@ FinishPreparedTransaction(const char *gid, bool isCommit)
14821481
delrels=abortrels;
14831482
ndelrels=hdr->nabortrels;
14841483
}
1485-
for (i=0;i<ndelrels;i++)
1486-
{
1487-
SMgrRelationsrel=smgropen(delrels[i],InvalidBackendId);
14881484

1489-
smgrdounlink(srel, false);
1490-
smgrclose(srel);
1491-
}
1485+
/* Make sure files supposed to be dropped are dropped */
1486+
DropRelationFiles(delrels,ndelrels, false);
14921487

14931488
/*
14941489
* Handle cache invalidation messages.

‎src/backend/access/transam/xact.c

Lines changed: 3 additions & 22 deletions
Original file line numberDiff line numberDiff line change
@@ -5373,7 +5373,6 @@ xact_redo_commit(xl_xact_parsed_commit *parsed,
53735373
RepOriginIdorigin_id)
53745374
{
53755375
TransactionIdmax_xid;
5376-
inti;
53775376
TimestampTzcommit_time;
53785377

53795378
Assert(TransactionIdIsValid(xid));
@@ -5494,16 +5493,8 @@ xact_redo_commit(xl_xact_parsed_commit *parsed,
54945493
*/
54955494
XLogFlush(lsn);
54965495

5497-
for (i=0;i<parsed->nrels;i++)
5498-
{
5499-
SMgrRelationsrel=smgropen(parsed->xnodes[i],InvalidBackendId);
5500-
ForkNumberfork;
5501-
5502-
for (fork=0;fork <=MAX_FORKNUM;fork++)
5503-
XLogDropRelation(parsed->xnodes[i],fork);
5504-
smgrdounlink(srel, true);
5505-
smgrclose(srel);
5506-
}
5496+
/* Make sure files supposed to be dropped are dropped */
5497+
DropRelationFiles(parsed->xnodes,parsed->nrels, true);
55075498
}
55085499

55095500
/*
@@ -5542,7 +5533,6 @@ xact_redo_commit(xl_xact_parsed_commit *parsed,
55425533
staticvoid
55435534
xact_redo_abort(xl_xact_parsed_abort*parsed,TransactionIdxid)
55445535
{
5545-
inti;
55465536
TransactionIdmax_xid;
55475537

55485538
Assert(TransactionIdIsValid(xid));
@@ -5607,16 +5597,7 @@ xact_redo_abort(xl_xact_parsed_abort *parsed, TransactionId xid)
56075597
}
56085598

56095599
/* Make sure files supposed to be dropped are dropped */
5610-
for (i=0;i<parsed->nrels;i++)
5611-
{
5612-
SMgrRelationsrel=smgropen(parsed->xnodes[i],InvalidBackendId);
5613-
ForkNumberfork;
5614-
5615-
for (fork=0;fork <=MAX_FORKNUM;fork++)
5616-
XLogDropRelation(parsed->xnodes[i],fork);
5617-
smgrdounlink(srel, true);
5618-
smgrclose(srel);
5619-
}
5600+
DropRelationFiles(parsed->xnodes,parsed->nrels, true);
56205601
}
56215602

56225603
void

‎src/backend/storage/smgr/md.c

Lines changed: 38 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -26,6 +26,7 @@
2626
#include<sys/file.h>
2727

2828
#include"miscadmin.h"
29+
#include"access/xlogutils.h"
2930
#include"access/xlog.h"
3031
#include"catalog/catalog.h"
3132
#include"pgstat.h"
@@ -1704,6 +1705,43 @@ ForgetDatabaseFsyncRequests(Oid dbid)
17041705
}
17051706
}
17061707

1708+
/*
1709+
* DropRelationFiles -- drop files of all given relations
1710+
*/
1711+
void
1712+
DropRelationFiles(RelFileNode*delrels,intndelrels,boolisRedo)
1713+
{
1714+
SMgrRelation*srels;
1715+
inti;
1716+
1717+
srels=palloc(sizeof(SMgrRelation)*ndelrels);
1718+
for (i=0;i<ndelrels;i++)
1719+
{
1720+
SMgrRelationsrel=smgropen(delrels[i],InvalidBackendId);
1721+
1722+
if (isRedo)
1723+
{
1724+
ForkNumberfork;
1725+
1726+
for (fork=0;fork <=MAX_FORKNUM;fork++)
1727+
XLogDropRelation(delrels[i],fork);
1728+
}
1729+
srels[i]=srel;
1730+
}
1731+
1732+
smgrdounlinkall(srels,ndelrels,isRedo);
1733+
1734+
/*
1735+
* Call smgrclose() in reverse order as when smgropen() is called.
1736+
* This trick enables remove_from_unowned_list() in smgrclose()
1737+
* to search the SMgrRelation from the unowned list,
1738+
* with O(1) performance.
1739+
*/
1740+
for (i=ndelrels-1;i >=0;i--)
1741+
smgrclose(srels[i]);
1742+
pfree(srels);
1743+
}
1744+
17071745

17081746
/*
17091747
*_fdvec_resize() -- Resize the fork's open segments array

‎src/include/storage/smgr.h

Lines changed: 1 addition & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -143,5 +143,6 @@ extern void RememberFsyncRequest(RelFileNode rnode, ForkNumber forknum,
143143
BlockNumbersegno);
144144
externvoidForgetRelationFsyncRequests(RelFileNodernode,ForkNumberforknum);
145145
externvoidForgetDatabaseFsyncRequests(Oiddbid);
146+
externvoidDropRelationFiles(RelFileNode*delrels,intndelrels,boolisRedo);
146147

147148
#endif/* SMGR_H */

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