On Mon, Mar 23, 2015 at 3:04 PM, defelix <[email protected]> wrote:
> Sorry Andrea, my mistake,
> now there is anymore the "SELECT TOP 100000" part but still remains the
> first line of the query:
> SELECT count(*) FROM (SELECT * FROM
> [JRC_EURDEP_PUBLIC_DM].[dbo].[fn_LastANDMaxDoseRateHourlyAverages_3]
> ('2015-02-13','2015-03-13 13:00')
>
> Unfortunately this line is an overhead for the performance issue, is there
> any chance to get rid of it?
>
Hmm... no, there is no easy way.
The "sql views" are currently implemented using a subquery in the from
clause, as you
can see, in order to:
* avoid having to parse/understand the query, which might be complex and
using db specific syntax
* pass down all the filters that we got in the wms/wfs/sld to the database
In order to cut away the first line we'd have to do a full parse of the
query itself, recognize its
bits, and see that we can just replace the select * with a select count(*)
Even in simple queries like yours that's not a trivial amount of work... if
you are interested
in doing the work I can give you pointers to which parts of the code should
be modified,
for the sql parsing there are 2-3 open source libraries that can parse
common sql, but they
will likely break the moment some specific db stuff is used, so this
eventual new code path
would have to be made optional.
Cheers
Andrea
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