Re: Increasing GROUP BY CHAR columns speed

>I'm still not sure why the planner chose to sort rather than hash with
>oversized work_mem (is there an implied order in the query results I
>missed?).

Group by contains decimal column exchrate. Maybe pg is not capable to use
hash with numeric datatype.

> My guess is that this query can still get much faster if a hash is
> possible on the last part. It looks like the gain so far has more to do
> with sorting purely in memory which reduced the number of compares
> required. But that is just a guess.

I fixed this by adding cast to :::float

bilkaib.exchrate:::float

In this case query is much faster.
Hopefully this will not affect to result since numeric(13,8) can casted to
float without data loss.

Andrus.