arcgis 10.1 - Why can't I access a table in a personal geodatabase (.mdb) with arcpy after installing 64-bit geoprocessing?

I wrote and ran a simple script last year - it cycled through some line features, buffered them and then intersected with some other lines - it all worked fine.

I'm now trying to tweak the file to use a larger buffer, and it's not finding the database I am using to manage the loop and store the results.

This code:

rows = arcpy.SearchCursor("C:\\CEDAR_GIS\\SPEEDY3_GPS_DATA\\shapefiles\\Analysis\\Intersections.mdb\\final_to_school_routes_LINES") 

results in this error:

Traceback (most recent call last):

  File "C:\CEDAR_GIS\SPEEDY3_GPS_DATA\shapefiles\Analysis\GISbuff-GPSline_IntersectionTS.py", line 29, in 
    rows = arcpy.SearchCursor("C:\\CEDAR_GIS\\SPEEDY3_GPS_DATA\\shapefiles\\Analysis\\Intersections.mdb\\final_to_school_routes_LINES") #opens search cursor on Overlays_to_run
  File "C:\Program Files (x86)\ArcGIS\Desktop10.1\arcpy\arcpy\__init__.py", line 1133, in SearchCursor
    return gp.searchCursor(dataset, where_clause, spatial_reference, fields, sort_fields)
  File "C:\Program Files (x86)\ArcGIS\Desktop10.1\arcpy\arcpy\geoprocessing\_base.py", line 359, in searchCursor
    self._gp.SearchCursor(*gp_fixargs(args, True)))
IOError: "C:\CEDAR_GIS\SPEEDY3_GPS_DATA\shapefiles\Analysis\Intersections.mdb\final_to_school_routes_LINES" does not exist

But that table is in that database, and when I ran the script last year there was no error. I have since upgraded to ArcGIS 10.1 with SP1, which I think meant an upgrade to python. Has there been a change in the handling of .mdb files, or am I doing something stupid?

Answer

To my understanding, 64-bit background geoprocessing no longer supports personal geodatabases .mdb files. ESRI has a help resource that addresses the update to 64-bit processing. I believe running the script as a foreground process will default back to 32-bit processing (even with 64-bit background processing installed). This can be found at: http://resources.arcgis.com/en/help/main/10.1/index.html#/Background_Geoprocessing_64_bit/002100000040000000/

One user has tested the difference between 32 and 64-bit processing and found a marginal ~10% increase in processing speed on very large datasets. http://polygeo.com.au/2012/11/02/arcgis-for-desktop-10-1-service-pack-1-and-64bit-background-geoprocessing/

I hope this helps! I just discovered this site and wanted to help out the community.