> 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?
Aglio Database Solutions
In response to
pgsql-performance by date
|Next:||From: Jacques Caron||Date: 2005-06-27 22:40:53|
|Subject: Re: Forcing use of a particular index|
|Previous:||From: Vivek Khera||Date: 2005-06-27 21:11:47|
|Subject: Re: perl garbage collector|