Re: Queries not always using index on timestamp search

Mike Nolan wrote:
> Here are two queries (under 7.4.1):
>
> 'mytime' is a timestamp field that is indexed.
>
> select * from mytable where mytime > '2004-06-21'
>
> select * from mytable where mytime > current_date-3
>
> Looking at an explain on these queries, the first one will use the
> index and the second one will not, even though 'current_date-3'
> produces the same date as the hard-coded one in the first search.
>
> Is there a way to get the second query to use the index?

Probably the simplest is to define a function ago(int) that does the
calculation for you. Mark the function STABLE and that should do it. See
the archives for more discussion of this.

--
Richard Huxton
Archonet Ltd