Re: q: explain analyze

From: Mark <sendmailtomark(at)yahoo(dot)com>
To: Jaime Casanova <systemguards(at)gmail(dot)com>, pgsql-general(at)postgresql(dot)org
Subject: Re: q: explain analyze
Date: 2006-01-10 19:12:47
Message-ID: 20060110191247.65117.qmail@web31907.mail.mud.yahoo.com
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This is great,
Now here's my explain analyze:

Seq Scan on balance (cost=0.00..54.51 rows=147 width=106) (actual
time=0.026..0.767 rows=62 loops=1)
Filter: (amount >= 0::double precision)

I do have an index on amount, but I guess it won't be used for >= ...
is there any way to force usage of index?

another question:
Can I defined index for _NOT_EQUAL_ ?

I have a column that can have 5 values and my where is
WHERE type <> 'A' OR type <> 'B'

_or_ better to use:
WHERE type ='C' OR type = 'D' OR type = 'E'

Thank you,

Mark.
--- Jaime Casanova <systemguards(at)gmail(dot)com> wrote:

> On 1/10/06, Mark <sendmailtomark(at)yahoo(dot)com> wrote:
> > Hello,
> >
> > When I run 'explain analyze' on a query, how do I know what index
> is
> > used and is it used at all. What are specific words should I look
> > for?
> >
> > Is "Seq Scan" indicates that index has been used?
> > How do I know that it was Full Table Scan?
> >
> > Thanks,
> > Mark.
> >
>
> "Seq Scan" is short for Sequential Scan (Full Table Scan)...
>
> you have to look for the word index to see what indexes are you
> using
> if any (the name of the indexes are used too, so if you now
> indexe's
> names you can find them in the explain analyze quickly)
>
> --
> Atentamente,
> Jaime Casanova
> (DBA: DataBase Aniquilator ;)
>


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