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Re: [HACKERS] RE: [GENERAL] Long update query ? (also Re: [GENERAL] CNF vs. DNF)

From: jwieck(at)debis(dot)com (Jan Wieck)
To: taral(at)mail(dot)utexas(dot)edu (Taral)
Cc: maillist(at)candle(dot)pha(dot)pa(dot)us, hackers(at)postgreSQL(dot)org
Subject: Re: [HACKERS] RE: [GENERAL] Long update query ? (also Re: [GENERAL] CNF vs. DNF)
Date: 1998-10-02 17:31:18
Message-ID: m0zP930-000EBQC@orion.SAPserv.Hamburg.dsh.de (view raw or flat)
Thread:
Lists: pgsql-generalpgsql-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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#======================================== jwieck(at)debis(dot)com (Jan Wieck) #


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