On Mon, Apr 26, 2004 at 02:29:58PM +0100, Simon Riggs wrote:
> On Sun, 2004-04-25 at 22:34, Manfred Koizar wrote:
> > Is there a special reason for scanning the leaf pages in *logical*
> > order, i.e. by following the opaque->btpo_next links? Now that FSM
> > covers free btree index pages this access pattern might be highly
> > nonsequential.
>
> I had considered implementing a mode where the index doesn't keep trying
> to reuse space that was freed by earlier deletes. For many situations
> where you are processing bulk inserts and bulk deletes, reusing space
> via the FSM ends up weaving the logical sequence into a very unsorted
> physical sequence.
>
> i.e. my thinking was about a way to keep logical looking more like
> physical, in certain situations.
See this:
@inproceedings{DBLP:conf/sigmod/ZouS96,
author = {Chendong Zou and Betty Salzberg},
editor = {H. V. Jagadish and Inderpal Singh Mumick},
title = {On-line Reorganization of Sparsely-populated B+trees},
booktitle = {Proceedings of the 1996 ACM SIGMOD International Conference on
Management of Data, Montreal, Quebec, Canada, June 4-6, 1996},
publisher = {ACM Press},
year = {1996},
pages = {115-124},
bibsource = {DBLP, \url{http://dblp.uni-trier.de}}
}
Maybe it can be useful.
When I tried to implement it, there was no free-pages code, so first I
had to do that (Tom Lane beat me to it though). Then I had to choose a
different project. Maybe now it can be done.
--
Alvaro Herrera (<alvherre[a]dcc.uchile.cl>)
One man's impedance mismatch is another man's layer of abstraction.
(Lincoln Yeoh)
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