Sami Dalouche <skoobi(at)free(dot)fr> writes:
> So, what could prevent postgrs from using the index ?
You've carefully withheld all the details that might let us guess.
If I had to guess anyway, I'd guess this is a pre-8.2 PG release
that doesn't know how to rearrange outer joins, but there are any
number of other possibilities.
If you want useful help on a query planning issue, you generally need
to provide
- the exact Postgres version
- full schema declaration of the relevant tables
- exact queries tested
- full EXPLAIN ANALYZE output
With less info than that, people are just shooting in the dark.
regards, tom lane