From: | Elvis Pranskevichus <elprans(at)gmail(dot)com> |
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To: | pgsql-hackers(at)postgresql(dot)org |
Cc: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Andres Freund <andres(at)anarazel(dot)de> |
Subject: | Re: WITH NOT MATERIALIZED and DML CTEs |
Date: | 2019-06-03 17:44:44 |
Message-ID: | 8773800.aLnjnIGtRz@hammer.magicstack.net |
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Thread: | |
Lists: | pgsql-hackers |
On Monday, June 3, 2019 1:03:44 P.M. EDT Tom Lane wrote:
> CASE is a scalar-expression construct. It's got little to do with
> the timing of scan/join operations such as row fetches. We offer
> users essentially no control over when those happen ... other than
> the guarantees about CTE materialization, which are exactly what
> you say you want to give up.
In the general case, yes, but I *can* use a scalar-returning INSERT CTE
in a THEN clause as a subquery. Useful for a conditional INSERT, when
you can't use ON CONFLICT.
Anyway, I understand that the complications are probably not worth it.
Thanks,
Elvis
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