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Re: Number of attributes in HeapTupleHeader

From: Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: Manfred Koizar <mkoi-pg(at)aon(dot)at>, pgsql-hackers(at)postgresql(dot)org
Subject: Re: Number of attributes in HeapTupleHeader
Date: 2002-06-12 18:23:16
Message-ID: 200206121823.g5CINGq14824@candle.pha.pa.us (view raw, whole thread or download thread mbox)
Thread:
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Tom Lane wrote:
> I said:
> > Sorry, you used up your chance at claiming that t_hoff is dispensable.
> > If we apply your already-submitted patch, it isn't.
> 
> Wait, I take that back.  t_hoff is important to distinguish how much
> bitmap padding there is on a particular tuple --- but that's really
> only interesting as long as we aren't forcing dump/initdb/reload.
> If we are changing anything else about tuple headers, then that
> argument becomes irrelevant anyway.
> 
> However, I'm still concerned about losing safety margin by removing
> "redundant" fields.

I just wanted to comment that redundancy in the tuple header, while
adding a very marginal amount to stability, is really too high a cost. 
If we can save 4 bytes on every row stored, I think that is a clear win.

-- 
  Bruce Momjian                        |  http://candle.pha.pa.us
  pgman(at)candle(dot)pha(dot)pa(dot)us               |  (610) 853-3000
  +  If your life is a hard drive,     |  830 Blythe Avenue
  +  Christ can be your backup.        |  Drexel Hill, Pennsylvania 19026

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