[postgis-users] composite key index (again)

[Charlton Purvis]

Hi, guys:
 
I know I've bugged y'all about this before, but for the life of me I can't remember what your 2 Canadian cents advice was.  And that's worth a lot of USD!  Paul, I think you threw me a bone earlier, but I can't find the thread neither physically nor mentally.
 
Say I have this snazzy table:
 
charlton (
  my_time timestamp without time zone,
  my_geom POINT
);
 
And say that every single MapServer query against this table is always done by selecting both time and space.  I know I'll have to track down the order, but say I also magically figure out that it's always time and then space.  (Actually that's the way it should be -- I've beem playing w/ the CLUSTER command, but unless I have the best indices around, it won't be of much use).
 
How can I create a composite key index w/ a timestamp without time zone column and a geometry column?  Something akin to using a betree for the time and a gist for the geom.  I know I can do a btree(my_time, my_geom), but that won't cut it for the && operator I don't think.  However, doing a gist of the two gives me a friendly:
 
sea_coos_obs=# create index dang_index_doesnt_work on charlton using gist(my_time,my_geom);
ERROR:  data type timestamp without time zone has no default operator class for access method "gist"
HINT:  You must specify an operator class for the index or define a default operator class
 
I know the HINT actually means something to smart people.  Also, I imagine I'd like to throw varchar in on the composite action.
 
Mind jogging my memory?
 
Thanks,
 
Charlton
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