Karl,
> Seems to me that when there's a constant value in the query
> and an = comparision it will always be faster to use the (b-tree)
> index that's ordered first by the constant value, as then all further
> blocks are guarenteed to have a higher relevant information
> density. At least when compared with another index that has the
> same columns in it.
That really depends on the stats. Such a choice would *not* be
appropriate if the < comparison was expected to return 1- rows while the =
condition applied to 15% of the table.
What is your STATISTICS_TARGET for the relevant columns set to? When's
the last time you ran analyze? If this is all updated, you want to post
the pg_stats rows for the relevant columns?
--
--Josh
Josh Berkus
Aglio Database Solutions
San Francisco