Re: COALESCE does short circuit - NOT

From: rjamya <rjamya_at_gmail.com>
Date: Thu, 19 Jan 2012 10:57:50 -0500
Message-ID: <CAGurbTM53cUWKUNGqQfApMyHf3CUV0rqC7yE+=MLec5zz8k=yw_at_mail.gmail.com>



I am guessing that happens because seq_test.nextval is treated like a function whose value is unknown, so it must be evaluated before null check can be performed.

like I said, I am just guessing, this is probably true with any non constant value, although I have not tested it.

Raj

2012/1/19 "Uwe Küchler" <uwe_at_kuechler.org>:
> "Short Circuit" means, the database evaluates each expr value and
> determines whether it is NULL, rather than evaluating all of the expr
> values before determining whether any of them is NULL.

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Received on Thu Jan 19 2012 - 09:57:50 CST

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