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Re: Review: Fix snapshot taking inconsistencies

From: Marko Tiikkaja <marko(dot)tiikkaja(at)cs(dot)helsinki(dot)fi>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: Steve Singer <ssinger_pg(at)sympatico(dot)ca>, pgsql-hackers(at)postgresql(dot)org, Alvaro Herrera <alvherre(at)commandprompt(dot)com>
Subject: Re: Review: Fix snapshot taking inconsistencies
Date: 2011-02-28 19:18:55
Message-ID: 4D6BF51F.6080906@cs.helsinki.fi (view raw or flat)
Thread:
Lists: pgsql-hackers
On 2011-02-28 9:03 PM, Tom Lane wrote:
> Marko Tiikkaja<marko(dot)tiikkaja(at)cs(dot)helsinki(dot)fi>  writes:
>> On 2011-02-28 8:22 PM, Tom Lane wrote:
>>> So: exactly what is the intended behavioral change as of now, and what
>>> is the argument supporting that change?
>
>> The only intended change is what I was wondering in the original post:
>> snapshot handling between normal execution and EXPLAIN ANALYZE when a
>> query expands to multiple trees because of rewrite rules.  Like I said
>> earlier, this is just a bugfix now that wCTEs don't need it anymore.
>
> OK, and which behavior is getting changed, to what?  I am not interested
> in trying to reverse-engineer a specification from the patch.

My recollection is (and the archives seem to agree) that normal 
execution and SQL functions were changed to only advance the CID instead 
of taking a new snapshot.  EXPLAIN ANALYZE and SPI (not exactly sure 
about this one) did that already so they were just changed to use the 
new API.


Regards,
Marko Tiikkaja

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Subject: Re: EXPLAIN doesn't show sufficient info for wCTE cases
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