Tweak MongoDB sink

Author: linda33wj

articles/data-factory/connector-azure-cosmos-db-mongodb-api.md

@@ -10,7 +10,7 @@ ms.service: multiple
 ms.workload: data-services
 ms.tgt_pltfrm: na
 ms.topic: conceptual
-ms.date: 08/01/2019
+ms.date: 11/20/2019
 ms.author: jingwang
 
 ---
@@ -166,7 +166,7 @@ The following properties are supported in the Copy Activity **sink** section:
 | Property | Description | Required |
 |:--- |:--- |:--- |
 | type | The **type** property of the Copy Activity sink must be set to **CosmosDbMongoDbApiSink**. |Yes |
-| writeBehavior |Describes how to write data to Azure Cosmos DB. Allowed values: **insert** and **upsert**.<br/><br/>The behavior of **upsert** is to replace the document if a document with the same ID already exists; otherwise, insert the document.<br /><br />**Note**: Data Factory automatically generates an ID for a document if an ID isn't specified either in the original document or by column mapping. This means that you must ensure that, for **upsert** to work as expected, your document has an ID. |No<br />(the default is **insert**) |
+| writeBehavior |Describes how to write data to Azure Cosmos DB. Allowed values: **insert** and **upsert**.<br/><br/>The behavior of **upsert** is to replace the document if a document with the same `_id` already exists; otherwise, insert the document.<br /><br />**Note**: Data Factory automatically generates an `_id` for a document if an `_id` isn't specified either in the original document or by column mapping. This means that you must ensure that, for **upsert** to work as expected, your document has an ID. |No<br />(the default is **insert**) |
 | writeBatchSize | The **writeBatchSize** property controls the size of documents to write in each batch. You can try increasing the value for **writeBatchSize** to improve performance and decreasing the value if your document size being large. |No<br />(the default is **10,000**) |
 | writeBatchTimeout | The wait time for the batch insert operation to finish before it times out. The allowed value is timespan. | No<br/>(the default is **00:30:00** - 30 minutes) |