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Commit9e53171

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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 parent5fca035 commit9e53171

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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
@@ -1456,7 +1456,6 @@ FinishPreparedTransaction(const char *gid, bool isCommit)
14561456
RelFileNode*delrels;
14571457
intndelrels;
14581458
SharedInvalidationMessage*invalmsgs;
1459-
inti;
14601459

14611460
/*
14621461
* Validate the GID, and lock the GXACT to ensure that two backends do not
@@ -1549,13 +1548,9 @@ FinishPreparedTransaction(const char *gid, bool isCommit)
15491548
delrels=abortrels;
15501549
ndelrels=hdr->nabortrels;
15511550
}
1552-
for (i=0;i<ndelrels;i++)
1553-
{
1554-
SMgrRelationsrel=smgropen(delrels[i],InvalidBackendId);
15551551

1556-
smgrdounlink(srel, false);
1557-
smgrclose(srel);
1558-
}
1552+
/* Make sure files supposed to be dropped are dropped */
1553+
DropRelationFiles(delrels,ndelrels, false);
15591554

15601555
/*
15611556
* Handle cache invalidation messages.

‎src/backend/access/transam/xact.c

Lines changed: 3 additions & 22 deletions
Original file line numberDiff line numberDiff line change
@@ -5516,7 +5516,6 @@ xact_redo_commit(xl_xact_parsed_commit *parsed,
55165516
RepOriginIdorigin_id)
55175517
{
55185518
TransactionIdmax_xid;
5519-
inti;
55205519
TimestampTzcommit_time;
55215520

55225521
Assert(TransactionIdIsValid(xid));
@@ -5635,16 +5634,8 @@ xact_redo_commit(xl_xact_parsed_commit *parsed,
56355634
*/
56365635
XLogFlush(lsn);
56375636

5638-
for (i=0;i<parsed->nrels;i++)
5639-
{
5640-
SMgrRelationsrel=smgropen(parsed->xnodes[i],InvalidBackendId);
5641-
ForkNumberfork;
5642-
5643-
for (fork=0;fork <=MAX_FORKNUM;fork++)
5644-
XLogDropRelation(parsed->xnodes[i],fork);
5645-
smgrdounlink(srel, true);
5646-
smgrclose(srel);
5647-
}
5637+
/* Make sure files supposed to be dropped are dropped */
5638+
DropRelationFiles(parsed->xnodes,parsed->nrels, true);
56485639
}
56495640

56505641
/*
@@ -5683,7 +5674,6 @@ xact_redo_commit(xl_xact_parsed_commit *parsed,
56835674
staticvoid
56845675
xact_redo_abort(xl_xact_parsed_abort*parsed,TransactionIdxid)
56855676
{
5686-
inti;
56875677
TransactionIdmax_xid;
56885678

56895679
Assert(TransactionIdIsValid(xid));
@@ -5748,16 +5738,7 @@ xact_redo_abort(xl_xact_parsed_abort *parsed, TransactionId xid)
57485738
}
57495739

57505740
/* Make sure files supposed to be dropped are dropped */
5751-
for (i=0;i<parsed->nrels;i++)
5752-
{
5753-
SMgrRelationsrel=smgropen(parsed->xnodes[i],InvalidBackendId);
5754-
ForkNumberfork;
5755-
5756-
for (fork=0;fork <=MAX_FORKNUM;fork++)
5757-
XLogDropRelation(parsed->xnodes[i],fork);
5758-
smgrdounlink(srel, true);
5759-
smgrclose(srel);
5760-
}
5741+
DropRelationFiles(parsed->xnodes,parsed->nrels, true);
57615742
}
57625743

57635744
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"pgstat.h"
3132
#include"portability/instr_time.h"
@@ -1703,6 +1704,43 @@ ForgetDatabaseFsyncRequests(Oid dbid)
17031704
}
17041705
}
17051706

1707+
/*
1708+
* DropRelationFiles -- drop files of all given relations
1709+
*/
1710+
void
1711+
DropRelationFiles(RelFileNode*delrels,intndelrels,boolisRedo)
1712+
{
1713+
SMgrRelation*srels;
1714+
inti;
1715+
1716+
srels=palloc(sizeof(SMgrRelation)*ndelrels);
1717+
for (i=0;i<ndelrels;i++)
1718+
{
1719+
SMgrRelationsrel=smgropen(delrels[i],InvalidBackendId);
1720+
1721+
if (isRedo)
1722+
{
1723+
ForkNumberfork;
1724+
1725+
for (fork=0;fork <=MAX_FORKNUM;fork++)
1726+
XLogDropRelation(delrels[i],fork);
1727+
}
1728+
srels[i]=srel;
1729+
}
1730+
1731+
smgrdounlinkall(srels,ndelrels,isRedo);
1732+
1733+
/*
1734+
* Call smgrclose() in reverse order as when smgropen() is called.
1735+
* This trick enables remove_from_unowned_list() in smgrclose()
1736+
* to search the SMgrRelation from the unowned list,
1737+
* with O(1) performance.
1738+
*/
1739+
for (i=ndelrels-1;i >=0;i--)
1740+
smgrclose(srels[i]);
1741+
pfree(srels);
1742+
}
1743+
17061744

17071745
/*
17081746
*_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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