From: David Garamond <davidgaramond@gmail.com>
To: Pavel Stehule <pavel.stehule@gmail.com>
To: pgsql-sql@postgresql.org
Subject: Re: Array: comparing first N elements?
Date: Tue, 12 May 2009 15:40:02 +0700
Message-ID: <7c33d060905120140p78b4e180rda6101cff30459eb@mail.gmail.com> (raw)
In-Reply-To: <162867790905120128h1dff1ba3mdc9c511af938e595@mail.gmail.com>
References: <7c33d060905120105y74b0483eyf5d94c07912a0702@mail.gmail.com>
<162867790905120128h1dff1ba3mdc9c511af938e595@mail.gmail.com>
On Tue, May 12, 2009 at 3:28 PM, Pavel Stehule <pavel.stehule@gmail.com>wrote:
> Hello
>
> create or replace function eqn(anyarray, anyarray, int)
> returns boolean as $$
> select not exists(select $1[i] from generate_series(1,$3) g(i)
> except
> select $2[i] from generate_series(1,$3) g(i))
> $$ language sql immutable strict;
>
> postgres=# select eqn(array[1,2,3,4,5], array[1,2,3,5,6], 3);
> eqn
> -----
> t
> (1 row)
>
> Time: 1,590 ms
> postgres=# select eqn(array[1,2,3,4,5], array[1,2,3,5,6], 4);
> eqn
> -----
> f
> (1 row)
>
Hi Pavel,
Thanks for the solution, but that's too slow. I'd rather just do this
instead:
select * from product
where parents[1:(select array_length(parents,1) from product where
name='wanted')+1]=
(select parents from product where name='wanted')||
(select id from product where name='wanted');
but the above query is also unable to use any indices (unlike LIKE 'foo%').
Regards,
Dave
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To: pgsql-sql@postgresql.org
Cc: davidgaramond@gmail.com, pavel.stehule@gmail.com
Subject: Re: Array: comparing first N elements?
In-Reply-To: <7c33d060905120140p78b4e180rda6101cff30459eb@mail.gmail.com>
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