Re: How to find out about index

Sounds like your running an older version of postgresql

Robert Treat

On Tue, 2002-10-08 at 04:44, Savita wrote:
> Hi Martijn and Shridhar
>
> Thanks very much for your help.
>
>
> I have one more question
>
>
> When I type the command
> CYCLE4#EXPLAIN ANALYZE
> CYCLE4# select * from os_customer_master where
> OUTSOURCER_LEGACY_CUSTOMER_ID='66';
> why I get the error
> ERROR: parser: parse error at or near "ANALYZE"
>
>
> is the command what I am typing is correct or it should be typed in
> different way.
>
>
>
> Martijn van Oosterhout wrote:
>
>
> On Tue, Oct 08, 2002 at 12:22:15PM +0530, Savita wrote:
> > Hi,
> >
> > What does the row indicate in the NOTICE: QUERY PLAN:
> >
> > I am getting diff-2 values which is not same as the actual row present
> in the table.
>
> Note that EXPLAIN produces an *estimate* of the number of rows.
> Obviously it
> can't know the exact number unless it actually runs the query. EXPLAIN
> ANALYZE will give you both the estimate and the actual.
>
>
> > Seq Scan on os_customer_master (cost=0.00..22.50 rows=10 width=112)
> > Index Scan using cust_1 on os_customer_master (cost=0.00..12.22
> rows=11 width=112)
> >
> > I can see that the cost has reduced but the rows has increased. What
> does
> > this means and also what does width means.
>
>
> It just means that due to some extra info, it estimates closer to 11
> than 10
> rows. It doesn't say anything about how many rows there really are.
>
>
> The width is the estimated size of the tuples. If there is only one
> field
> needed, the width will be small. You can see it change if you change the
>
> columns output.
>
>
> Try EXPLAIN ANALYZE.
>