[mapserver-dev] Ready for 5.6.2?

[Frank Warmerdam]

Tamas Szekeres wrote:
> Hi All,
> 
> #3356 looks good, however I have a couple of strange issues with regards 
> to the single-pass query to the OGR data sources.
> Unfortunately I haven't had enough time to look into the details and 
> identify the location, however it seems like the followings may happen:
> 
> 1. Performing a querybyRect, resultsGetShape may select wrong features.

Tamas,

I wrote a small test script (msautotest/mspython/ogr_query.py) and I
did not observe any problems with resultsGetShape() and queryByRect().
What problem were you expecting?

> 2. resultsGetShape may retrieve different features when panning the view 
> within the same selection. (A persistent mapObj reference is required 
> between the pan operations to test this)

I can confirm that if doing a draw on the layer effectively invalidates
the last query result since the draw applies a different spatial query
criteria to the layer, clearing the one from the last query operation.

I hadn't really imagine applications would expect query results to
persist through major operations like a draw.

> 3. GetShape doesn't work anymore (ie. the former 2 pass approach). It 
> retrieves null shapes with no items.

I did not observe any problem with it in my testing.  Of course, you
can't necessarily use the id's from the resultset since they are not
FIDs.  But if, somehow, you know the fid's you want you can fetch them
with GetShape().

> 4. Moving the selected shapes outside of the visible region MapServer 
> triggers an error (failed to draw layer)

I'm not clear on what you mean by moving them around.

> Could someone confirm whether the query is working with the OGR data 
> sources at all, using the current stable branch?

It seems to me that query is working as I had expected on OGR layers.
I will concede that with the advent of one pass query resultsets can no
longer be considered "long lived" in the face of other operations on a
map.

Best regards,
-- 
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I set the clouds in motion - turn up   | Frank Warmerdam, warmerdam at pobox.com
light and sound - activate the windows | http://pobox.com/~warmerdam
and watch the world go round - Rush    | Geospatial Programmer for Rent