[Mapserver-dev] Query efficiency

Daniel Morissette dmorissette at dmsolutions.ca
Wed Mar 3 14:11:03 EST 2004

Steve Lime wrote:
> I don't know what various databases do with caching. There is no notion
> of a result set (other than a list of indicies) within MapServer, and
> there is
> certainly nothing source specific. That's probably a good place to look
> for
> starters. I could see allowing each supported datasource type
> maintaining
> it's own version of a result set (e.g. a list of indicies for
> shapefiles) and then
> we write generic wrappers to access the result set. That way a
> particular
> datasource would not be forced down the "get shape by id" path that
> works
> well for shapefiles. The Refractions folks would be in the best
> position to
> comment since they know PostGIS far better than anyone knows SDE or
> Oracle Spatial. This probably complicates the notion of cached
> queries.

What we mean exactly by "caching queries"?  I see two possible meanings:

1- Caching results between multiple hits to the CGI (or to mapscript 

2- Optimizing MapServer's internals to avoid doing multiple passes on 
the data in a single request when doing query-related operations.

Is it just me, or are we mixing both here?

I have a feeling that we're talking about #1, but some people are hoping 
that you're talking about #2.

  Daniel Morissette               dmorissette at dmsolutions.ca
  DM Solutions Group              http://www.dmsolutions.ca/

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