Re: The exact timing at which CHECK constraints are checked

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Takahiro Noda <noda(dot)takahiro(dot)47m(at)st(dot)kyoto-u(dot)ac(dot)jp>
Cc: pgsql-novice(at)postgresql(dot)org
Subject: Re: The exact timing at which CHECK constraints are checked
Date: 2011-12-15 06:41:24
Message-ID: 26634.1323931284@sss.pgh.pa.us
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Takahiro Noda <noda(dot)takahiro(dot)47m(at)st(dot)kyoto-u(dot)ac(dot)jp> writes:
> I'm new to PostgreSQL and having been learning SQL. I'm uncertain
> about the exact timing at which CHECK constraints are checked.

They're checked at the instant that a row is inserted or updated.
If you really need a deferred check, you'll need to build it yourself
using an AFTER ROW trigger.

regards, tom lane

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