"Dave [Hawk-Systems]" <dave(at)hawk-systems(dot)com> writes:
> have a data table that records entries by date(unix timestamp) and customer
> number. each custnum will have several entries showing a running ledger type
> snapshot. we have the need to get the most recent entry from not one, but all
> unique customers, in the most cost effective manner.
If you don't mind using a Postgres-only construct, SELECT DISTINCT ON
is made for this. See the "weather report" example in the SELECT
reference page.
regards, tom lane