[Mapserver-dev] Query efficiency

bartvde at xs4all.nl bartvde at xs4all.nl
Wed Mar 3 08:37:56 EST 2004

Hi Steve,

would it not make sense to make a difference between local datasources,
like shapefiles, and (spatial) database datasources?

When you have a database datasource you can leave a lot of work to the
database, including the caching of query results.

It doesn't seem logical to me that 2 queries are needed in the current
design for all datasources (for a database datasource 1 query should
suffice most of the times).

But I don't know if this fits into the current design of Mapserver queries.

So perhaps not the caching of result sets is the solution (although always
a nice enhancement feature I guess), but changing the way the queries are
sent to the database datasources is the way to go.

Just a thought.

Best regards,

> Hi guys: The issue of query efficiency keeps coming up these days as
> queries are not simply a means to an end. SVG, image maps etc... are
> going to push the current code, especially with non-shapefile
> datasources. I/we need to figure out a way to cache shapes that are part
> of a query result set. We could use the inline feature structures to do
> this but I worry about huge result sets, and/or could consider
> serializing shapes to some high performance format. There are some
> interesting possibilities with the latter. Query caching could be made
> very efficient (e.g. queryfile/savequery CGI options) and that format
> could be useful for regular layers too, kind of like the gd2 format.
> What do folks think?
> Steve
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