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.
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 K�chler" <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.
-- http://www.freelists.org/webpage/oracle-lReceived on Thu Jan 19 2012 - 09:57:50 CST