curious delay on view/where

Hi folks.

I have the following view:

CREATE VIEW "stock_available" as
SELECT * FROM stock_details
WHERE available = true AND visible = true AND
location not in (SELECT descr FROM ignored);

Stock_details is itself a view pulling in a number of tables. Everything
works fine until I try to pull in only the details for a specific
branch, using the following.

select * from stock_available where branch = 'Leeds';
or
select * from stock_available where branch = 'Doncaster';

At this point, the query takes 11 seconds. Any other quiery, including

select * from stock_available where branch != 'Doncaster'
and
select * from stock_available where branch != 'Leeds'

which only return the equivelent of the top two (we only have Leeds and
Doncaster) are les than 1 second.

Anyone got any ideas of the cause, or thoughts on how I can trace the
problem?

--
Gary Stainburn

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