Connect to ESRI Personal Geodatabase

[Frank Warmerdam]

On 7/6/05, Frank Warmerdam <fwarmerdam at gmail.com> wrote:
> On 7/6/05, Mike Davis <mike.and.kerry at gmail.com> wrote:
> > Funding things where I work is like pulling teeth, but I will inquire
> > with the "powers that be" to see if it is possible, this is a feature
> > we would really like to have (especially if the performace is close to
> > that of shapefiles).

Mike,

There are two main issues affecting performance. 

1) Spatial indexing.  Personal geodatabase does have a spatial
index table associated with spatial tables.  If we can properly utilize
this we ought to be able to grab small spatial regions out of big tables
effeciently.  If not, it will be as corresponding slow as a shapefile would
be without a spatial index.  I'm not really confident I can utilize the 
spatial index yet though.  I looked at a sample file Howard provided, 
and the index table just had 0's and -1's in the spatial index table.
I don't know if I was using too old a version of MS Access to look at it, 
or if it wasn't built or what.  

2) ODBC and OGR translation overhead.  Both of these layers add
significant performance drag. 

I can't give any real guarantees for performance, but if we can get
spatial indexing working it shouldn't be too much worse than direct
shapefiles.  

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