From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
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To: | andrew(at)pillette(dot)com |
Cc: | pgsql-performance(at)postgresql(dot)org |
Subject: | Re: How do I see what triggers are called on cascade? |
Date: | 2004-08-24 02:50:41 |
Message-ID: | 27145.1093315841@sss.pgh.pa.us |
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Lists: | pgsql-performance |
andrew(at)pillette(dot)com writes:
> I'm still having trouble with slow cascading DELETEs. What commands can I issue to see the sequence of events that occurs after I execute
> DELETE FROM x WHERE p;
> so that I can see if indexes being used correctly, or I have a constraint I don't want, etc.
I'd suggest starting a fresh backend, turning on log_statement, and then
issuing the DELETE. log_statement will log the queries generated by the
foreign-key triggers ... but only the first time through, because those
triggers cache the query plans.
The queries you will see will be parameterized (they'll use $1,$2,etc).
You can use PREPARE and EXPLAIN ANALYZE EXECUTE to investigate what sort
of plans result.
regards, tom lane
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