List of events around a coordinate during a period of time?

As above.

I've tried the FQL query

SELECT eid FROM event WHERE 
   (start_time > 2011-08-19T03:00:00+0000) AND (end_time < 2011-08-19T08:00:00+0000) AND
   ((venue.latitude + 0.005 > 23.7490375) OR (venue.latitude - 0.005 < 23.7490375)) AND
   ((venue.longitude + 0.005 > 90.39463031) OR (venue.longitude - 0.005 < 90.39463031)))

The result I got was

Your statement is not indexable. The WHERE clause must contain an indexable column. Such columns are marked开发者_StackOverflow中文版 with * in the tables linked from http://developers.facebook.com/docs/reference/fql

Is there a way to get this information using either facebook or some other database service?

There is no way to search with the level of detail you are looking for.

Within FQL, the event table needs an index, you can try using AND CONTAINS('a') to select all events that contain the character a. It's a very brute force approach.