man pg-dump + triggers

From: Dan Langille <dan(at)langille(dot)org>
To: pgsql-bugs(at)postgresql(dot)org
Subject: man pg-dump + triggers
Date: 2003-03-11 04:00:53
Message-ID: 20030310224621.B62620@xeon.unixathome.org
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I found this hard to comprehend upon the first reading:

When doing a data only dump, pg_dump emits queries to disable triggers on
user tables before inserting the data and queries to re-enable them after
the data has been inserted. If the restore is stopped in the middle, the
system catalogs may be left in the wrong state.

I first thought that pg_dump issues a command to disable triggers. What
it meant, I think, is that pg_dump includes those commands within the
output. Those commands are actually processed/issued by pg_restore (or
perhaps psql in a 'psql mydb < mydump.sql' fashion.

If my impressions are correct, then I think the following is more
appropriate:

When doing a data-only dump, pg_dump will output data insert statements
that are wrapped with a pair of commands to first disable and then re-enable
triggers on user tables. If the restore is stopped in the middle
of the inserts, the system catalogs may be left in the wrong state.

NOTE: I am not sure that "catalogs may be left in the wrong state" is the
correct phrase to use.

cheers

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