BatchWrite limits

Question

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

Answer

Thanks for the clarification.

Answer

Apologies, the wording of the error message could be improved. I'll create an item in our internal bug tracker.   
  
You are correct that there are 11 Objects created. When the error message says "Write objects, max: 20, actual: 22", it is using the "little o" definition of object (anything in your directory) rather than the "big O" definition of Object (a node in the directory's graph). This can certainly cause confusion. In your case, the additional writes are coming from the creation of the links from "/object/index" to each child. Both Links and Objects count towards this write limit.  
  
-Matt

BatchWrite limits

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