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We're migrating some feature classes from SDELOB (or some older binary format) to ST_Geometry. As we write our arcpy script to use the ESRI Migrate Storage Tool we'd like to test whether or not something already is ST_Geom...Other than writing hooks into the database, using the comtypes package etc., does anyone know of a simple way to determine this?

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up vote 6 down vote accepted

To follow-up on PolyGeo's answer, the Describe object is certainly where it should be, but it isn't. Database queries may be the best way to go here.

Although, if you have the SDE command-line binaries, another option would be to try doing something like this (yes it's a hack, but might work):

import subprocess
output = subprocess.check_output("sdelayer -o describe_long -s servername -D dbname -u username -p password -l tablename,columname")
for line in output:
    if line.find("Layer Type") == 0:
        storagetype = line.partition(":")[2].strip() # Should be something like "SDE-BINARY" or "Extended SQL Type/ST_GEOMETRY"
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It would be good if the Describe object were able to access this.

This has now been submitted as an ArcGIS Idea (on which you can vote).

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This should be more accessible through ArcPy but in the meantime we can take advantage of the SDE registry tables to find the answer. The SDE.GEOMETRY_COLUMNS table contains the names of feature classes F_TABLE_NAME, their schema owner F_TABLE_SCHEMA, and their corresponding geometry table name G_TABLE_NAME.

If the feature and geometry table names are the same then the feature class' geometry is stored in the same table as the attributes; otherwise the geometry is stored in a separate feature table (aka "F" table).

So our SQL query would be something like:

WHERE F_TABLE_SCHEMA || '.' || G_TABLE_NAME = :featureClassName

For ArcPy, assume "GEODATABASE.sde" is the name of an SDE connection file and "GIS.TAX_PARCELS_POLY" is the name of a feature class stored in the "GIS" schema:

import arcpy, os

dstFeatureClass = "sde/DC_LISDBA (GIS).sde/GIS.PARCEL_PARCELS_POLY"

#open a connection to the geodatabase
wks = arcpy.ArcSDESQLExecute(os.path.dirname(dstFeatureClass))

#create the SQL query statement
sql = \
    "WHERE F_TABLE_SCHEMA || '.' || G_TABLE_NAME = " + \
    "'" + os.path.basename(dstFeatureClass) + "'"

#execute the query and return the geometry type
print "ST_Geometry" if wks.execute(sql) else "SDEBINARY"

#delete the geodatabase connection
del [wks, sql]

Note this solution only tells you if the geometry is stored in the same table as the feature class and not the actual column type (e.g. SDEBINARY, SDELOB, ST_Geometry) though I do believe that can be found elsewhere in the SDE tables or Oracle.

This could also be further optimized by creating an Oracle function and/or creating a view on the SDE.GEOEMTRY_COLUMNS table.

* Tested with ArcSDE 10.2.2 on Oracle 11g (64-bit).

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