Thread: index or not

index or not

From
"Jean-Yves F. Barbier"
Date:
Hi list,

I wonder if indexes are relevant or not on a small table?
(250 rows, 10 columns, often retrieved in different order)

JY
--
If you have never been hated by your child, you have never been a
parent. -- Bette Davis

Re: index or not

From
Andreas Kretschmer
Date:
Jean-Yves F. Barbier <12ukwn@gmail.com> wrote:

> Hi list,
>
> I wonder if indexes are relevant or not on a small table?
> (250 rows, 10 columns, often retrieved in different order)

Don't ask us, ask EXPLAIN instead! ;-)


Andreas
--
Really, I'm not out to destroy Microsoft. That will just be a completely
unintentional side effect.                              (Linus Torvalds)
"If I was god, I would recompile penguin with --enable-fly."   (unknown)
Kaufbach, Saxony, Germany, Europe.              N 51.05082°, E 13.56889°

Re: index or not

From
"Jean-Yves F. Barbier"
Date:
On Mon, 12 Dec 2011 19:15:32 +0100
Andreas Kretschmer <akretschmer@spamfence.net> wrote:

> > I wonder if indexes are relevant or not on a small table?
> > (250 rows, 10 columns, often retrieved in different order)
>
> Don't ask us, ask EXPLAIN instead! ;-)

The PB is, it is in dev state and not filled; from what I read
on the site about indexes, I would say "no" -  so I ask here to
see if somebody has a return of experience.

--
Psychiatry is the care of the id by the odd.

Re: index or not

From
Andreas Kretschmer
Date:
Jean-Yves F. Barbier <12ukwn@gmail.com> wrote:

> On Mon, 12 Dec 2011 19:15:32 +0100
> Andreas Kretschmer <akretschmer@spamfence.net> wrote:
>
> > > I wonder if indexes are relevant or not on a small table?
> > > (250 rows, 10 columns, often retrieved in different order)
> >
> > Don't ask us, ask EXPLAIN instead! ;-)
>
> The PB is, it is in dev state and not filled; from what I read
> on the site about indexes, I would say "no" -  so I ask here to
> see if somebody has a return of experience.

As i said: use EXPLAIN. The answer of your question depends on a lot of
details, i can't say if an seq-scan is cheaper or not. (for instance, if
you have SSDs, a index-scan maybe is cheaper than an seq-scan ...)

Create an Index, use explain, if it use a seq-scan you can drop the index.

For such small tables it is hard to guess the plan...


Andreas
--
Really, I'm not out to destroy Microsoft. That will just be a completely
unintentional side effect.                              (Linus Torvalds)
"If I was god, I would recompile penguin with --enable-fly."   (unknown)
Kaufbach, Saxony, Germany, Europe.              N 51.05082°, E 13.56889°

Re: index or not

From
"Jean-Yves F. Barbier"
Date:
On Mon, 12 Dec 2011 20:26:06 +0100
Andreas Kretschmer <akretschmer@spamfence.net> wrote:

>
> As i said: use EXPLAIN. The answer of your question depends on a lot of
> details, i can't say if an seq-scan is cheaper or not. (for instance, if
> you have SSDs, a index-scan maybe is cheaper than an seq-scan ...)
>
> Create an Index, use explain, if it use a seq-scan you can drop the index.
>
> For such small tables it is hard to guess the plan...

Ok, I'll create indexes (no time to test right now), thanks.

--
"Take that, you hostile sons-of-bitches!"
-- James Coburn, in the finale of _The_President's_Analyst_