Re: index on to_char(created, 'YYYY') doesn't work

On Wed, 15 Jan 2003, Andreas Joseph Krogh wrote:

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> On Wednesday 15 January 2003 11:37, you wrote:
> > The following does not work:
> >
> > create index session_u_idx on session (to_char(created, 'YYYY'));
> > ERROR: parser: parse error at or near "'YYYY'" at character 57
> >
> > Can I make a function to do this and index using the result of that
> > funtion? Do anyone have an example of such a function?
>
> I tried the following function:
> - -----------------------------------------------------------------
> create function drus (timestamp) returns varchar AS'
> DECLARE
> str_created VARCHAR;
> created ALIAS FOR $1;
> BEGIN
> str_created:= to_char(created, ''YYYY'');
> RETURN str_created;
> END;
> ' LANGUAGE 'plpgsql';

add
WITH (iscachable)

>
> create index session_u_idx on session (drus(created));
> - -----------------------------------------------------------------
> But it failes with:
> ERROR: DefineIndex: index function must be marked isImmutable
>
> Now the question is how do I mark an index function isImmutable?
>
> - --
> Andreas Joseph Krogh <andreak(at)officenet(dot)no>
> There will always be someone who agrees with you
> but is, inexplicably, a moron.
>
> gpg public_key: http://dev.officenet.no/~andreak/public_key.asc
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Achilleus Mantzios
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