[daisy] COUNT in queries

[Bruno Dumon]

On Wed, 2006-07-26 at 18:18 +0200, Yves Langisch wrote:
> Hi,
> 
> Is there an easy way to count the elements of the resultset returned by
> a query? I couldn't find any COUNT function for the query language. My
> current workaround is to read the size in my custom stylesheet from
> <ns:resultInfo size="5" chunkOffset="1" chunkLength="5"/> which is not
> very efficient in case of a big resultset (the whole resultset is in the
> response).

There's no count function (the query language returns always lists of
documents, unlike e.g. SQL).

We'll likely soon look into adding pagination of query results
(currently only present for faceted queries), with this you would be
able to ask a chunk of size '0' to avoid transporting the result set.

In the meantime, some hints for optimalisation:

 * don't select any data. However, the query language requires you to
select at least one thing. So you can do e.g. 'select id where...'.

 * don't use an order by clause as that won't influence the count

-- 
Bruno Dumon                             http://outerthought.org/
Outerthought - Open Source, Java & XML Competence Support Center
bruno at outerthought.org                          bruno at apache.org