Improve speed of rendering engine by not using "select * from table"

[ksgeograf]

The current render engine will load the entire row from the datasource. This involves a potentially large overhead, as it typically needs only a few columns to style the layer.

In a test case I worked on, I was able to reduce render time from 20 to 12 seconds, just by removing unused columns from the dataset.

This solution does not work when the data is required for anything but rendering.

For a simple fix, I propose that the render figures out what columns are used by looking at the scalerange condition rules and tooltip.

It might introduce a significant overhead to preparse this data. If this overhead is inacceptable, the RuntimeMap could include this information, so that it is done once pr. map, and not at each rendering.

[tomfukushima]

Thanks Kenneth, the speedup that you are seeing is pretty substantial.

[zspitzer]

I have seen this speedup effect as well. Anyone using AutoCAD Map with ther database has their performance crippled by this as Map adds all 20 odd ADMP* columns to tables.

[jng]

#771 sound very much like this issue.

[stevedang]

Fixed by submission <<<​http://trac.osgeo.org/mapguide/changeset/3469>>>.

[ronnielouie]

Re-opened ticket due to reverting of previous fix since it was incomplete.

​http://trac.osgeo.org/mapguide/changeset/3499

[jbirch]

The solution seems pretty complex, and unless someone's been doing a lot of work in a local copy I'd guess that this won't be making it into 2.1... If this is the case, could you please reset or remove the Milestone?

[jbirch]

Changing to enhancement, removing version. Would be nice to see this addressed, but at least it's possible to optimize (views, data etl).