Index usage ?

Hi,
I'm making a database with table of over 50 000 000 i
created index on some columns but they are used only
in range search (e.g. WHERE column<100 AND column>10)
and point rearch (e.g. WHERE column=100). When I try
to execute some queries using only <,>,<= or >=  index
is not used.

 So is there any way to force ysage of the index with
this conditions.
I'm using BTREE as noted in Pg users guide.

please help!

regards,
Rumen

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