Thread

1. Re: [HACKERS] Adding a field to each tuple

   Maurice Gittens <mgittens@gits.nl> — 1998-02-26T09:45:28Z

   -----Original Message-----
   From: Bruce Momjian <maillist@candle.pha.pa.us>
   To: Maurice Gittens <mgittens@gits.nl>
   Cc: hackers@postgreSQL.org <hackers@postgreSQL.org>
   Date: donderdag 26 februari 1998 2:09
   Subject: Re: [HACKERS] Adding a field to each tuple
   
   
   >> My challenge:
   >> Given an oid, efficiently determine the most derived class the instance
   >> belongs to.
   >>
   >> My intended solution is to add an extra attribute to each tuple
   >> which contains the oid of the most derived class it belongs to.
   >
   
   
   I expect it will also introduce me to quite a few aspects of the postgresql
   system.
   If I'm going to learn about the system then I might as well get a good
   overall
   view of how things are organized.
   Sure I've read parts of the developers manual but I think this little
   project will let
   me see (in the source) how information travels from diskstorage all the
   way to the client.
   Also valuable information on how to debug the backend etc. will be
   learned in this way I think.
   
   While trying to fix a large_object memory leak I noticed
   that without an understanding of how the many components interrelate
   it's almost impossible to fix anything because you don't know who is
   responsible for what.
   
   I certainly do appreciate any help I can get.
   >
   > This is a lot of overhead for places it is not needed.
   >
   
   Any suggestions for solving the general given problem with less overhead?-:)
   
   Best regards,
   Maurice
   
   
   
   

2. Re: [HACKERS] Adding a field to each tuple

   Bruce Momjian <maillist@candle.pha.pa.us> — 1998-02-26T14:31:48Z

   > I certainly do appreciate any help I can get.
   > >
   > > This is a lot of overhead for places it is not needed.
   > >
   > 
   > Any suggestions for solving the general given problem with less overhead?-:)
   
   Yes, this is a natural use for a trigger.  Create the column in the base
   table, and have it stuff the value on insert.  You have to make the
   trigger on each derived table, but you may be able to use the same
   trigger on all tables.  This is how we are implementing time travel.
   
   
   -- 
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