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Commitb77da19

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Fix O(N^2) behavior in pg_dump for large numbers of owned sequences.
The loop that matched owned sequences to their owning tables required timeproportional to number of owned sequences times number of tables; althoughthis work was only expended in selective-dump situations, which is probablywhy the issue wasn't recognized long since. Refactor slightly so that wecan perform this work after the index array for findTableByOid has beenset up, reducing the time to O(M log N).Per gripe from Mike Roest. Since this is a longstanding performance bug,backpatch to all supported versions.
1 parent6205bb6 commitb77da19

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3 files changed

+27
-18
lines changed

3 files changed

+27
-18
lines changed

‎src/bin/pg_dump/common.c

Lines changed: 3 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -126,6 +126,9 @@ getSchemaData(int *numTablesPtr)
126126
tblinfo=getTables(&numTables);
127127
tblinfoindex=buildIndexArray(tblinfo,numTables,sizeof(TableInfo));
128128

129+
/* Do this after we've built tblinfoindex */
130+
getOwnedSeqs(tblinfo,numTables);
131+
129132
if (g_verbose)
130133
write_msg(NULL,"reading user-defined functions\n");
131134
funinfo=getFuncs(&numFuncs);

‎src/bin/pg_dump/pg_dump.c

Lines changed: 23 additions & 18 deletions
Original file line numberDiff line numberDiff line change
@@ -3856,38 +3856,43 @@ getTables(int *numTables)
38563856

38573857
PQclear(res);
38583858

3859+
destroyPQExpBuffer(query);
3860+
3861+
returntblinfo;
3862+
}
3863+
3864+
/*
3865+
* getOwnedSeqs
3866+
* identify owned sequences and mark them as dumpable if owning table is
3867+
*
3868+
* We used to do this in getTables(), but it's better to do it after the
3869+
* index used by findTableByOid() has been set up.
3870+
*/
3871+
void
3872+
getOwnedSeqs(TableInfotblinfo[],intnumTables)
3873+
{
3874+
inti;
3875+
38593876
/*
38603877
* Force sequences that are "owned" by table columns to be dumped whenever
38613878
* their owning table is being dumped.
38623879
*/
3863-
for (i=0;i<ntups;i++)
3880+
for (i=0;i<numTables;i++)
38643881
{
38653882
TableInfo*seqinfo=&tblinfo[i];
3866-
intj;
3883+
TableInfo*owning_tab;
38673884

38683885
if (!OidIsValid(seqinfo->owning_tab))
38693886
continue;/* not an owned sequence */
38703887
if (seqinfo->dobj.dump)
38713888
continue;/* no need to search */
3872-
3873-
/* can't use findTableByOid yet, unfortunately */
3874-
for (j=0;j<ntups;j++)
3889+
owning_tab=findTableByOid(seqinfo->owning_tab);
3890+
if (owning_tab&&owning_tab->dobj.dump)
38753891
{
3876-
if (tblinfo[j].dobj.catId.oid==seqinfo->owning_tab)
3877-
{
3878-
if (tblinfo[j].dobj.dump)
3879-
{
3880-
seqinfo->interesting= true;
3881-
seqinfo->dobj.dump= true;
3882-
}
3883-
break;
3884-
}
3892+
seqinfo->interesting= true;
3893+
seqinfo->dobj.dump= true;
38853894
}
38863895
}
3887-
3888-
destroyPQExpBuffer(query);
3889-
3890-
returntblinfo;
38913896
}
38923897

38933898
/*

‎src/bin/pg_dump/pg_dump.h

Lines changed: 1 addition & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -514,6 +514,7 @@ extern OpclassInfo *getOpclasses(int *numOpclasses);
514514
externOpfamilyInfo*getOpfamilies(int*numOpfamilies);
515515
externConvInfo*getConversions(int*numConversions);
516516
externTableInfo*getTables(int*numTables);
517+
externvoidgetOwnedSeqs(TableInfotblinfo[],intnumTables);
517518
externInhInfo*getInherits(int*numInherits);
518519
externvoidgetIndexes(TableInfotblinfo[],intnumTables);
519520
externvoidgetConstraints(TableInfotblinfo[],intnumTables);

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