From: | elein <elein(at)sbcglobal(dot)net> |
---|---|
To: | David Wheeler <david(at)kineticode(dot)com>, elein(at)varlena(dot)com |
Cc: | sfpug(at)postgresql(dot)org |
Subject: | Re: Multifunction Indexes |
Date: | 2003-03-15 01:20:05 |
Message-ID: | 200303150124.h2F1OIlK367312@pimout2-ext.prodigy.net |
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Thread: | |
Lists: | sfpug |
I've got functions on the brain.
So...turn it into a functional index. You can
pass more than one column into a functional index.
On Friday 14 March 2003 16:39, David Wheeler wrote:
> On Friday, March 14, 2003, at 04:25 PM, elein wrote:
> > As a workaround, push the lower() function into the
> > workflow() function. Of course if the workflow doesn't
> > always want lower($1) then you'll have to overload or rename it.
>
> Uh, but workflow is a table, not a function.
>
I've got functions on the brain. Sorry. You are correct.
So...turn it into a functional index. You can
pass more than one column into a functional index.
create [unique] index fidx on workflow ( foo( name, site_id) );
where foo is
create function foo(text,text) returns text as '
select lower($1)||$2;
' language 'SQL' IMMUTABLE;
Then when you query and want to use the functional index
you must call it as where xxx = foo(name,site_id)
The downside is that functional indexes won't allow you to
use partial indexes.
> > I'm don't know the structures like Stephen does.
> > But if a plain expression parser were used consistently
> > it should be able to enable expressions rather
> > than single functions. The expression tree would need
> > to be held rather than the function function pointer.
> > And of course all of it should be immutable.
> >
> > Then again theory is nice, but practice is a whole 'nother
> > ball game.
>
> Yes...not sure I understand what you're saying here...perhaps that
> allowing multiple function indexes for function plus column indexes
> should be do-able if the parser understood the syntax properly?
Yes, I'm saying it should work on any expression, but I don't know
enough to do anything but theorize :-)
>
> Regards,
>
> David
elein
--
----------------------------------------------------------------------------------------
elein(at)varlena(dot)com Database Consulting www.varlena.com
I have always depended on the [QA] of strangers.
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