[postgis-users] selectivity

Ben midfield at gmail.com
Mon Nov 1 16:18:30 PDT 2010

hello --

i am not a postgis user, but i am interested in range datatypes and gist indexing.  there are some extensions for postgresql which expose such types (temporal, cube, etc.) but as far as i can tell all of them use the default geometric operator selectivity functions, which are all stubs in mainline postgresql and return hard-coded constants -- not ideal.

i've been investigating postgis and it appears that you have real selectivity functions for your operators.

1 - is this true?  do they work well?  which operators work?  (&&, @>, etc)?

2 - is there any documentation describing how they work (besides the source code)?  i'm interested in the kind of statistics you use.

3 - would it be possible for someone to backport the selectivity functions to, say, temporal postgres or cube?  would you recommend it?

best regards, ben

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