On Wed, Feb 20, 2008 at 12:56:54AM -0800, Postgres User wrote:
> a final question: why does this syntax do a seq scan + filter:
>
> select * from tablea where fielda = fielda -or- select * from
> tablea where fielda in (fielda)
>
> while this syntax results in no filter, seq scan only
>
> select * from tablea where 1 = 1
>
> it seems that both where clauses should be ignored by the optimizer-
> or am i missing something
WHERE fielda = fielda will only match non-null rows...
Have a nice day,
--
Martijn van Oosterhout <kleptog@svana.org> http://svana.org/kleptog/
> Those who make peaceful revolution impossible will make violent revolution inevitable.
> -- John F Kennedy