Discarding relations from FSM

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