Skip site navigation (1) Skip section navigation (2)

Peripheral Links

Header And Logo

PostgreSQL
| The world's most advanced open source database.

Site Navigation

Search for
  Advanced Search

Discarding relations from FSM


  • From: "Jim C. Nasby" <jnasby(at)pervasive(dot)com>
  • To: pgsql-hackers(at)postgresql(dot)org
  • Subject: Discarding relations from FSM
  • Date: Sat, 24 Sep 2005 18:04:50 -0500
  • Message-id: <20050924230450(dot)GQ7630(at)pervasive(dot)com>

Per http://lnk.nu/developer.postgresql.org/43b.c:

 * The number of distinct relations tracked is limited by a configuration
 * variable (MaxFSMRelations).  When this would be exceeded, we discard the
 * least recently used relation.  A doubly-linked list with move-to-front
 * behavior keeps track of which relation is least recently used.

Rather than keeping track of which relation was last used (presumably
everytime something hits the FSM), wouldn't it make more sense to just
drop the relation with the smallest amount of free space in the map?

Of course maybe a better question is why we even limit based on the
number of relations...
-- 
Jim C. Nasby, Sr. Engineering Consultant      jnasby(at)pervasive(dot)com
Pervasive Software      http://pervasive.com    work: 512-231-6117
vcard: http://jim.nasby.net/pervasive.vcf       cell: 512-569-9461



Home | Main Index | Thread Index

Privacy Policy | PostgreSQL Archives hosted by Command Prompt, Inc. | Designed by tinysofa
Copyright © 1996 – 2008 PostgreSQL Global Development Group