partial indexes

I have following situation:
one "message" table and 3 other "message_{1,2,3}" tables which inherit
from "message".
Every day +-50 000 "messages" are being inserted.

I needed something  extra to speed up the queries instead of only using
indexes, so I thought of doing something like you can do in Oracle,
table partitioning.
In postgresql you can simulate this using the partial indexes.

So what I did was:
made an "today_idx", "2_weeks_idx", "1 month_idx" on the attribute
"sent_date" to speed up the queries using the "sent_date"
attribute,which 90% of the times is queried on. These indexes are
rebuild every night.

When I was testing this setup, the indexes I used where like:
today_idx: 1/02
2_weeks_idx: 18/01  -->  1/02
month_idx: 2/01 --> 1/02

When quering something like:
select * from messages where sent_date = '2004-02-01'

the optimiser chooses to search in the month_idx index instead of using
the optimal today_idx. This is because today (1/02) is also included in
the month_idx (and also the 2weeks_idx)
So I had to recreate the indexes excluding the previous ones and
borders. Is this normal?

My question:
Is this a good way to solve the problem? are there any other ways I can
do this?
Is the inheritance a good feature / stable in postgresql (not a lot of
documentation about)

Tnx in advance


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