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Subject: Re: temp table "on commit delete rows": transaction
	overhead
From: Artiom Makarov <artiom.makarov@gmail.com>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: pgsql-performance@postgresql.org
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2010/3/30 Tom Lane <tgl@sss.pgh.pa.us>:

> I don't recall any operations at transaction start for such tables,
> but there may be some.
>
Both in =F3ommitTransaction(void) and  PrepareTransaction(void) we can
see PreCommit_on_commit_actions() call;

Here PreCommit_on_commit_actions()
<CUT>
			case ONCOMMIT_DELETE_ROWS:
				oids_to_truncate =3D lappend_oid(oids_to_truncate, oc->relid);
				break;
<CUT>

As a my opinion, the same action taked place at transaction start and commi=
t.

To truncate rows of any temp tables, both  changed and unchanged(!)
after transaction looks as little reinsurance. Well.
But why do the same action _before_ any transaction?