clean up ClientRequestToken

xoto3/dynamodb/write_versioned/ddb_api.py

@@ -126,8 +126,13 @@ def boto3_transact_multiple_but_optimize_single(TransactItems: List[dict], **kwa
         if len(TransactItems) == 0:
             _log.debug("Nothing to transact - returning")
             return
+        # ClientRequestToken, if provided, indicates a desire to use
+        # certain idempotency guarantees provided only by
+        # TransactWriteItems. I'm not sure if it's even relevant for a
+        # single-item operation, but it's an issue of expense, not
+        # correctness, to leave it in.
         if len(TransactItems) == 1 and "ClientRequestToken" not in kwargs:
-            # attempt single put or delete to halve the cost
+            # attempt simple condition-checked put or delete to halve the cost
             command = TransactItems[0]
             item_args = tuple(command.values())[0]  # first and only value is a dict of arguments
             if set(command) == {"Put"}:
@@ -138,7 +143,7 @@ def boto3_transact_multiple_but_optimize_single(TransactItems: List[dict], **kwa
                 return
             if set(command) == {"ConditionCheck"}:
                 _log.debug(
-                    "A solitary ConditionCheck is meaningless - you already retrieved the item"
+                    "Item was not modified and is solitary - no need to interact with the table"
                 )
                 return
             # we don't (yet) support single write optimization for things other than Put or Delete
@@ -172,7 +177,6 @@ def _serialize_versioned_expr(expr: dict) -> dict:
 def built_transaction_to_transact_write_items_args(
     transaction: VersionedTransaction,
     last_written_at_str: str,
-    ClientRequestToken: str = "",
     item_version_attribute: str = "item_version",
     last_written_attribute: str = "last_written_at",
 ) -> dict:
@@ -261,7 +265,4 @@ def item_remains_unmodified(
             ]
         )
 
-    args: Dict[str, Any] = dict(TransactItems=transact_items)
-    if ClientRequestToken:
-        args["ClientRequestToken"] = ClientRequestToken
-    return args
+    return dict(TransactItems=transact_items)

xoto3/dynamodb/write_versioned/run.py

@@ -60,6 +60,10 @@ def versioned_transact_write_items(
     moment of the successful transaction completion, including items
     you did not need to modify.
 
+    An exception to the above rule is that if you interact with only
+    one item and you do not change it, we will not call
+    TransactWriteItems at all.
+
     Returns the completed transaction, which contains the resulting
     items as written to the table(s) at the completion of the
     transaction.
@@ -71,6 +75,7 @@ def versioned_transact_write_items(
     The implementation for transact_write_items will also optimize
     your DynamoDB costs by reverting to a simple (but still versioned)
     Put or Delete if you only operate on a single item.
+
     """
     batch_get_item, transact_write_items = boto3_impl_defaults(
         batch_get_item, transact_write_items,
@@ -90,7 +95,6 @@ def versioned_transact_write_items(
                 **built_transaction_to_transact_write_items_args(
                     built_transaction,
                     iso8601strict(datetime.utcnow()),
-                    "",
                     item_version_attribute,
                     last_written_attribute,
                 )