BatchWrite limits

Related a bit to forum https://forums.aws.amazon.com/post!reply.jspa?messageID=821050, but I don't think I should completely hijack that topic.

I'm performing the following batch_write operation using Python:

{
    'DirectoryArn': '<snip>', 
    'Operations': [
        {'CreateObject': {'SchemaFacet': [{'SchemaArn': '<snip>', 'FacetName': 'Organization'}], 'ObjectAttributeList': [{'Key': {'SchemaArn': '<snip>', 'FacetName': 'Organization', 'Name': 'display_name'}, 'Value': {'StringValue': 'Object #1'}}], 'ParentReference': {'Selector': '/'}, 'LinkName': 'object', 'BatchReferenceName': '5bd5059b-b793-4ebe-b45b-b0a136a4ac8d'}},
        {'CreateObject': {'SchemaFacet': [{'SchemaArn': '<snip>', 'FacetName': 'Meta'}], 'ObjectAttributeList': [{'Key': {'SchemaArn': '<snip>', 'FacetName': 'Meta', 'Name': 'display_name'}, 'Value': {'StringValue': 'Child #1'}}], 'ParentReference': {'Selector': '#5bd5059b-b793-4ebe-b45b-b0a136a4ac8d'}, 'LinkName': 'organization', 'BatchReferenceName': '01e66be7-d47f-40ed-b7d0-faa638db9ced'}},
        {'CreateObject': {'SchemaFacet': [{'SchemaArn': '<snip>', 'FacetName': 'Meta'}], 'ObjectAttributeList': [{'Key': {'SchemaArn': '<snip>', 'FacetName': 'Meta', 'Name': 'display_name'}, 'Value': {'StringValue': 'Child #2'}}], 'ParentReference': {'Selector': '#5bd5059b-b793-4ebe-b45b-b0a136a4ac8d'}, 'LinkName': 'index', 'BatchReferenceName': 'f8b672b9-fef5-40c8-8c55-94152d4db745'}},
        {'CreateObject': {'SchemaFacet': [{'SchemaArn': '<snip>', 'FacetName': 'INDEX'}], 'ObjectAttributeList': [], 'ParentReference': {'Selector': '#f8b672b9-fef5-40c8-8c55-94152d4db745'}, 'LinkName': 'index1', 'BatchReferenceName': '71b75012-516b-4cb6-8354-976ad1cc4589'}},
        {'CreateObject': {'SchemaFacet': [{'SchemaArn': '<snip>', 'FacetName': 'INDEX'}], 'ObjectAttributeList': [], 'ParentReference': {'Selector': '#f8b672b9-fef5-40c8-8c55-94152d4db745'}, 'LinkName': 'index2', 'BatchReferenceName': 'c6824a61-1338-4cd5-8d3a-553b67e50a18'}},
        {'CreateObject': {'SchemaFacet': [{'SchemaArn': '<snip>', 'FacetName': 'INDEX'}], 'ObjectAttributeList': [], 'ParentReference': {'Selector': '#f8b672b9-fef5-40c8-8c55-94152d4db745'}, 'LinkName': 'index3', 'BatchReferenceName': 'c72c0bab-25f1-4a83-a9c5-569d34d1a90d'}},
        {'CreateObject': {'SchemaFacet': [{'SchemaArn': '<snip>', 'FacetName': 'INDEX'}], 'ObjectAttributeList': [], 'ParentReference': {'Selector': '#f8b672b9-fef5-40c8-8c55-94152d4db745'}, 'LinkName': 'index4', 'BatchReferenceName': '8b4368e2-2d29-4666-8eb0-4e93105f1efb'}},
        {'CreateObject': {'SchemaFacet': [{'SchemaArn': '<snip>', 'FacetName': 'INDEX'}], 'ObjectAttributeList': [], 'ParentReference': {'Selector': '#f8b672b9-fef5-40c8-8c55-94152d4db745'}, 'LinkName': 'index5', 'BatchReferenceName': 'e5ba15a8-4cdd-43a7-873e-0afd8c0e6870'}},
        {'CreateObject': {'SchemaFacet': [{'SchemaArn': '<snip>', 'FacetName': 'INDEX'}], 'ObjectAttributeList': [], 'ParentReference': {'Selector': '#f8b672b9-fef5-40c8-8c55-94152d4db745'}, 'LinkName': 'index6', 'BatchReferenceName': 'afba33be-d2a2-461f-8742-ec0cb805b0dc'}},
        {'CreateObject': {'SchemaFacet': [{'SchemaArn': '<snip>', 'FacetName': 'INDEX'}], 'ObjectAttributeList': [], 'ParentReference': {'Selector': '#f8b672b9-fef5-40c8-8c55-94152d4db745'}, 'LinkName': 'index7', 'BatchReferenceName': 'c4b70cd5-1a39-45ba-a5ee-efb0fbc424e7'}},
        {'CreateObject': {'SchemaFacet': [{'SchemaArn': '<snip>', 'FacetName': 'INDEX'}], 'ObjectAttributeList': [], 'ParentReference': {'Selector': '#f8b672b9-fef5-40c8-8c55-94152d4db745'}, 'LinkName': 'index8', 'BatchReferenceName': '1ac0290c-339f-4b50-9080-d1c5c8d4159a'}}
    ]
}

which fails with the error:

An error occurred (LimitExceededException) when calling the BatchWrite operation: Limits exceeded on the request. Write objects, max: 20, actual: 22. Read objects, max: 200, actual: 10. Write attributes, max: 1000, actual: 4. Read attributes, max: 1000, actual: 0.

I'm creating 11 objects. The selector paths would look like:

/object
/object/organization
/object/index
/object/index/index1
/object/index/index2
/object/index/index3
/object/index/index4
/object/index/index5
/object/index/index6
/object/index/index7
/object/index/index8

Although I can understand where the 22 Writes come from, I wonder if this is a fair assumption as the object with "/object/index" is for example counted 9 times (1 create, 8 updates). I'm using the BatchReference so during the counting it can be taken into account that I intend to write the same object multiple times, and as it is documented that the batch_write is going to be a single transaction, I would expect my "Write object count" to be 12 (11 objects created + root node update.

This comment can also be extended a bit to the Read Objects count of 10, but I'll that one out of the discussion. :)