[Mapserver-users] OGR Join index

[Frank Warmerdam]

Richard Greenwood wrote:
> Very interesting! So I could use MapInfo to create indexes and OGR would 
>  use them? And if I wanted to use ORG's CREATE INDEX I would need to 
> write a C or Python wrapper? i.e. There is no stand alone CREATE INDEX 
> utility?

Richard,

Well, if you create the indexes with MapInfo, they won't be recognised because
there needs to be a little xml file that associates them.

You should create the indexes with the OGR "CREATE INDEX" command.  This
can be accomplished with the ogrinfo utility which includes the ability
to execute arbitrary OGR SQL.

eg.

warmerda at gdal2200[214]% ogrinfo -ro . -sql "create index on polygon using eas_"
INFO: Open of `.'
using driver `ESRI Shapefile' successful.
warmerda at gdal2200[215]% ls -la
total 368
drwxr-xr-x    2 warmerda users        4096 Jun 18 16:34 .
drwxr-xr-x   53 warmerda users        4096 Jun 18 16:32 ..
-rw-r--r--    1 warmerda users      159752 Jun 18 16:32 polygon.dbf
-rw-r--r--    1 warmerda users         221 Jun 18 16:34 polygon.idm
-rw-r--r--    1 warmerda users        8704 Jun 18 16:34 polygon.ind
-rw-r--r--    1 warmerda users      175784 Jun 18 16:32 polygon.shp
-rw-r--r--    1 warmerda users        3892 Jun 18 16:32 polygon.shx

Now that I think about it some more, I'm pretty certain that OGR doesn't even
take advantage of the indexes for mapfinfo format ... only for shapefiles right
now.  The client in question needed it only for shapefiles.

Best regards,
-- 
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I set the clouds in motion - turn up   | Frank Warmerdam, warmerdam at pobox.com
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and watch the world go round - Rush    | Geospatial Programmer for Rent