[Geowanking] Proposal: Improving on the ESRI Personal Geodatabase?

Alex Willmer alex at moreati.org.uk
Thu Nov 10 05:26:38 PST 2005


In my day job I support an ArcSDE/ArcIMS/ArcGIS infrastructure. The GIS
specialists frequently use Personal Geodatabases for offline editing,
temporary storage & project archival.

For those unfamiliar a Personal Geodatabase (PGDB) is an MS Access
database (.mdb) file with some predefined tables and table structures. A
PGDB can store multiple vector and raster layers with attributes, upto a
total size of 2 GiB. An overview can be found here:

http://www.esri.com/software/arcgis/geodatabase/about/personal.html

Recently I've been pondering that a similar concept would be of use to
opensource GIS systems. It could provide a format featuring:
- a single file able to hold multiple datatypes, and layers with indexed
access
- a zero-admin, portable implementation of Simple Features for SQL
- a common transport for moving geodata between disparate databases
- an alternative to shapefiles with fewer limitations on attributes,
types, identifiers etc

I don't suggest reverse engineering the PGDB format (although this would
also be of great use). I think something based on SQLite would fit the
bill. A 

The SQLite library is already popular as an embedded database in
opensource software. It smashes the PGDB limit of 2GiB (SQLite 3 can
potentially address files of 2 TiB). Finally, unlike mdb, SQLite has no
scripting built in - so virus scanners are less likely to interfere with
any file format based upon it (ie mail filters should let it through and
on-access scanners should ignore the potentially large files it would
support.)

Hoping for comments, suggestions & questions.

Regards

Alex




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