Horton

Re: Remove xmin and cmin from frozen tuples

Tom Lane <tgl@sss.pgh.pa.us>

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From: Tom Lane <tgl@sss.pgh.pa.us>
To: Alvaro Herrera <alvherre@alvh.no-ip.org>
Cc: Josh Berkus <josh@agliodbs.com>, pgsql-hackers@postgresql.org, Bruce Momjian <pgman@candle.pha.pa.us>, ITAGAKI Takahiro <itagaki.takahiro@lab.ntt.co.jp>
Date: 2005-09-02T21:16:09Z
Lists: pgsql-hackers 
Alvaro Herrera <alvherre@alvh.no-ip.org> writes:
> On Fri, Sep 02, 2005 at 01:35:42PM -0700, Josh Berkus wrote:
>> Where I do see value is in enabling index-only access for "frozen" tables.  
>> That would be a *huge* gain, especially with bitmaps.   I think we've 
>> discussed this before, though.

> That's a completely different discussion.  Btree-organized heaps may
> help you there.

There was some talk of using a spare bit in index entries to mark "known
good" index entries (xmin committed and less than GlobalXmin, and xmax
invalid) but the cost of maintaining such bits seems nontrivial.  In any
case I agree that's an independent issue.

			regards, tom lane