Re: [HACKERS] RE: [GENERAL] Long update query ? (also Re: [GENERAL] CNF vs. DNF) - Mailing list pgsql-hackers

From jwieck@debis.com (Jan Wieck)
Subject Re: [HACKERS] RE: [GENERAL] Long update query ? (also Re: [GENERAL] CNF vs. DNF)
Date
Msg-id m0zP930-000EBQC@orion.SAPserv.Hamburg.dsh.de
Whole thread Raw
In response to RE: [GENERAL] Long update query ? (also Re: [GENERAL] CNF vs. DNF)  ("Taral" <taral@mail.utexas.edu>)
Responses Re: [HACKERS] RE: [GENERAL] Long update query ? (also Re: [GENERAL] CNF vs. DNF)  (Bruce Momjian <maillist@candle.pha.pa.us>)
List pgsql-hackers
>
> > > Create a temporary oid hash? (for each table selected on, I guess)
> >
> > What I did with indexes was to run the previous OR clause index
> > restrictions through the qualification code, and make sure it failed,
> > but I am not sure how that is going to work with a more complex WHERE
> > clause.  Perhaps I need to restrict this to just simple cases of
> > constants, which are easy to pick out an run through.  Doing this with
> > joins would be very hard, I think.
>
> Actually, I was thinking more of an index of returned rows... After each
> subquery, the backend would check each row to see if it was already in the
> index... Simple duplicate check, in other words. Of course, I don't know how
> well this would behave with large tables being returned...
>
> Anyone else have some ideas they want to throw in?
>
> Taral
>

    But what about unions of join queries? Which OID's then should
    be checked against which? And unions from view selects? There
    are no OID's at all after rewriting.


Jan

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