Message-ID: <478BA7B8.2090907@p-dw.com>
Date: Mon, 14 Jan 2008 19:19:36 +0100
From: Patric <lists@p-dw.com>
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To: pgsql-performance@postgresql.org
Subject: Saving result set of SELECT to table column
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Hi,
   There will be some flames i suppose.
   Well I've a normalized database.. 
   For instance:

   create table Y ( pk, data...  );
   create table Z ( pk , data...    );

   create table X (  char, references  Y, references  Z);

   SELECT * from X;

   Now I want to make a listing of the result set from X.
   If there are references to Z or Y (not null refs), I want to display 
that data too.

   Normally I would SELECT, to get that data, not in my case.
   Nearly all queries will be SELECTs, no UPDATEs or INSERTs, so need to 
optimize that case.

   The dirty little denormalization would look like this:

   create table X ( char, ref. to Y, ref. to Z, StoreY Y , StoreZ Z);

   On insert or update of Z or Y, I would update these two (StoreY, 
StoreZ) columns by RULE or TRIGGER..
   I know this is not nice etc.. Codd would sue for this, but in my case 
performance over beauty is ok.
     I'm looking for something like UPDATE X set StoreY=(SELECT * FROM Y 
WHERE pk=4) WHERE foreignID2Y = 4;

   Is there a away to accomplish this straightforward  in a single 
statement without doing loops and stuff in a serverside procedure?

  Thanks in advance,
   Patric