On Thu, Oct 28, 2010 at 1:05 PM, Robert Haas <robertmhaas@gmail.com> wrote:
> On Tue, Oct 19, 2010 at 7:56 PM, Merlin Moncure <mmoncure@gmail.com> wrote:
>> On Mon, Oct 18, 2010 at 1:16 AM, AI Rumman <rummandba@gmail.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;
Hm, after a few quick tests it seems your approach is better in just
about every respect :-).
merlin
