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Fix pg_dump/pg_restore to restore event triggers later.

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Previously, event triggers were restored just after regular triggers
(and FK constraints, which are basically triggers).  This is risky
since an event trigger, once installed, could interfere with subsequent
restore commands.  Worse, because event triggers don't have any
particular dependencies on any post-data objects, a parallel restore
would consider them eligible to be restored the moment the post-data
phase starts, allowing them to also interfere with restoration of a
whole bunch of objects that would have been restored before them in
a serial restore.  There's no way to completely remove the risk of a
misguided event trigger breaking the restore, since if nothing else
it could break other event triggers.  But we can certainly push them
to later in the process to minimize the hazard.

To fix, tweak the RestorePass mechanism introduced by commit 3eb9a5e7c
so that event triggers are handled as part of the post-ACL processing
pass (renaming the "REFRESH" pass to "POST_ACL" to reflect its more
general use).  This will cause them to restore after everything except
matview refreshes, which seems OK since matview refreshes really ought
to run in the post-restore state of the database.  In a parallel
restore, event triggers and matview refreshes might be intermixed,
but that seems all right as well.

Also update the code and comments in pg_dump_sort.c so that its idea
of how things are sorted agrees with what actually happens due to
the RestorePass mechanism.  This is mostly cosmetic: it'll affect the
order of objects in a dump's TOC, but not the actual restore order.
But not changing that would be quite confusing to somebody reading
the code.

Back-patch to all supported branches.

Fabrízio de Royes Mello, tweaked a bit by me

Discussion: https://postgr.es/m/CAFcNs+ow1hmFox8P--3GSdtwz-S3Binb6ZmoP6Vk+Xg=K6eZNA@mail.gmail.com
This commit is contained in:
Tom Lane
2020-03-09 14:58:11 -04:00
parent c9a47b81ed
commit 0b02476442
3 changed files with 34 additions and 19 deletions
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19
src/bin/pg_dump/pg_backup_archiver.c
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@@ -641,11 +641,11 @@ RestoreArchive(Archive *AHX)
{
/*
* In serial mode, process everything in three phases: normal items,
* then ACLs, then matview refresh items. We might be able to skip
* one or both extra phases in some cases, eg data-only restores.
* then ACLs, then post-ACL items. We might be able to skip one or
* both extra phases in some cases, eg data-only restores.
*/
bool haveACL = false;
bool haveRefresh = false;
bool havePostACL = false;
for (te = AH->toc->next; te != AH->toc; te = te->next)
{
@@ -660,8 +660,8 @@ RestoreArchive(Archive *AHX)
case RESTORE_PASS_ACL:
haveACL = true;
break;
case RESTORE_PASS_REFRESH:
haveRefresh = true;
case RESTORE_PASS_POST_ACL:
havePostACL = true;
break;
}
}
@@ -676,12 +676,12 @@ RestoreArchive(Archive *AHX)
}
}
if (haveRefresh)
if (havePostACL)
{
for (te = AH->toc->next; te != AH->toc; te = te->next)
{
if ((te->reqs & (REQ_SCHEMA | REQ_DATA)) != 0 &&
_tocEntryRestorePass(te) == RESTORE_PASS_REFRESH)
_tocEntryRestorePass(te) == RESTORE_PASS_POST_ACL)
(void) restore_toc_entry(AH, te, false);
}
}
@@ -2906,8 +2906,9 @@ _tocEntryRestorePass(TocEntry *te)
strcmp(te->desc, "ACL LANGUAGE") == 0 ||
strcmp(te->desc, "DEFAULT ACL") == 0)
return RESTORE_PASS_ACL;
if (strcmp(te->desc, "MATERIALIZED VIEW DATA") == 0)
return RESTORE_PASS_REFRESH;
if (strcmp(te->desc, "EVENT TRIGGER") == 0 ||
strcmp(te->desc, "MATERIALIZED VIEW DATA") == 0)
return RESTORE_PASS_POST_ACL;
return RESTORE_PASS_MAIN;
}