On Thu, Oct 28, 2010 at 11:05 PM, Robert Haas <robertmhaas@xxxxxxxxx> wrote:
What aboutOn Tue, Oct 19, 2010 at 7:56 PM, Merlin Moncure <mmoncure@xxxxxxxxx> wrote:
> On Mon, Oct 18, 2010 at 1:16 AM, AI Rumman <rummandba@xxxxxxxxx> 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.
select crm.*, sum(1) over () as crm_count from crm limit 10;
--
Robert Haas
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