From: | Antonin Houska <ah(at)cybertec(dot)at> |
---|---|
To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
Cc: | Robert Haas <robertmhaas(at)gmail(dot)com>, "pgsql-hackers(at)postgresql(dot)org" <pgsql-hackers(at)postgresql(dot)org> |
Subject: | Re: Unnecessary checks for new rows by some RI trigger functions? |
Date: | 2019-02-25 07:20:10 |
Message-ID: | 3735.1551079210@localhost |
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Lists: | pgsql-hackers |
Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> Not sure what I think about your new proposed patch. What problem
> do you think it solves? Also, don't think I believe this:
>
> + * crosscheck_snapshot is actually used only for UPDATE / DELETE
> + * queries.
I wanted to clarify the meaning of crosscheck_snapshot, i.e. only set it when
it's needed. Anyway I don't feel now it's worth the amount of code changed.
> The commands we're issuing here are SELECT FOR UPDATE^H^H^HSHARE,
> and those should chase up to the newest row version and do a
> crosscheck just as UPDATE / DELETE would do. If they don't, there's
> a hazard of mis-enforcing the FK constraint in the face of
> concurrent updates.
Maybe I missed something. When I searched through the code I saw the
crosscheck_snapshot passed only to heap_update() and heap_delete().
--
Antonin Houska
https://www.cybertec-postgresql.com
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