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Re: [HACKERS] Optimizer fails?

From: "Vadim B(dot) Mikheev" <vadim(at)sable(dot)krasnoyarsk(dot)su>
To: David Gould <dg(at)illustra(dot)com>
Cc: Michal Mosiewicz <mimo(at)interdata(dot)com(dot)pl>, pgsql-hackers(at)postgreSQL(dot)org
Subject: Re: [HACKERS] Optimizer fails?
Date: 1998-03-30 02:38:08
Message-ID: 351F058F.CA40DEA0@sable.krasnoyarsk.su (view raw or flat)
Thread:
Lists: pgsql-hackers
David Gould wrote:
> 
> > Now, let's note, that there has been only a few IO transfers by now. No
> > more than few pages. And we have tupple identifiers pointing us to 64
> > records. Now we may sort this tids in ascending order to optimise IO.
> 
> But, we do not do this tid sort. It really isn't easy as you might have
> millions of tids, not just a few. Which would mean doing an external sort.
> This might be a nice thing to do, but it isn't there now as far as I know.

Using TID as (last) part of index key is on my TODO. 
This will speed up vacuuming, get rid of all duplicate key
problems and give us feature above.

> To scan the index to get the tids for keys 0...63 will take two page
> reads: root page, leaf1.

+ meta page read first - to get root page block number.

Vadim

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