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Re: how to get the total number of records in report

From: AI Rumman <rummandba(at)gmail(dot)com>
To: Robert Haas <robertmhaas(at)gmail(dot)com>
Cc: Merlin Moncure <mmoncure(at)gmail(dot)com>, pgsql-performance(at)postgresql(dot)org
Subject: Re: how to get the total number of records in report
Date: 2010-10-28 17:49:25
Message-ID: AANLkTi=nZ4JSXjHrNkCP=HT226-8-muZRLwR89KU-rwz@mail.gmail.com (view raw or flat)
Thread:
Lists: pgsql-performance
But I am using Postgresql 8.1 and it is not possible to write query as your
one here.

On Thu, Oct 28, 2010 at 11:05 PM, Robert Haas <robertmhaas(at)gmail(dot)com> wrote:

> On Tue, Oct 19, 2010 at 7:56 PM, Merlin Moncure <mmoncure(at)gmail(dot)com>
> wrote:
> > On Mon, Oct 18, 2010 at 1:16 AM, AI Rumman <rummandba(at)gmail(dot)com> wrote:
> >> At present for reporting I use following types of query:
> >> select crm.*, crm_cnt.cnt
> >> from crm,
> >> (select count(*) as cnt from crm) crm_cnt;
> >> Here count query is used to find the total number of records.
> >> Same FROM clause is copied in both the part of the query.
> >> Is there any other good alternative way to get this similar value?
> >
> > Probably the best way to do this type of thing is handle it on the
> > client.  However, if you want to do it this way and your from clause
> > is more complex than 'from table', you can possibly improve on this
> > with a CTE:
> >
> > with q as (select * from <something expensive>)
> > select q.* q_cnt.cnt from q, (select count(*) as cnt from q) q_cnt;
> >
> > The advantage here is that the CTE is materialized without having to
> > do the whole query again.  This can be win or loss depending on the
> > query.
>
> What about
>
> select crm.*, sum(1) over () as crm_count from crm limit 10;
>
> --
> Robert Haas
> EnterpriseDB: http://www.enterprisedb.com
> The Enterprise PostgreSQL Company
>

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