Re: loop with circular updates - Mailing list pgsql-general

From Tom Lane
Subject Re: loop with circular updates
Date
Msg-id 24722.1154101568@sss.pgh.pa.us
Whole thread Raw
In response to Re: loop with circular updates  (Jessica M Salmon <jmsalmon@fs.fed.us>)
Responses Re: loop with circular updates  (Jessica M Salmon <jmsalmon@fs.fed.us>)
List pgsql-general
Jessica M Salmon <jmsalmon@fs.fed.us> writes:
>       -is it true that when looping over query results in a plpgsql
> for..in..execute loop, several records are stored in memory at one time?

Yes, but that's got nothing to do with your issue.

>       -if I then update one of the records currently in memory, are these
> changes visible when the loop gets to it?

*All* queries in Postgres see a snapshot as of the instant of query
start.  This is a property of the MVCC rules and has nothing to do with
buffering.  What's returned by a FOR IN EXECUTE is whatever was in the
database when the loop began.

            regards, tom lane

pgsql-general by date:

Previous
From: Michael Fuhr
Date:
Subject: Re: Create spatial_ref_sys entry from srtext ?
Next
From: "Sandeep Kumar Jakkaraju"
Date:
Subject: Help