feat: [document-compression-updater]- Improvements: Auto-remove dummy compression field, drop tracker collection and more

operations/document-compression-updater/README.md

@@ -1,13 +1,15 @@
 # Python Updater tool 
-This sample applications compresses pre-existing documents in an existing collection after compression is turned on that existing collection.
+This sample application compresses pre-existing documents in an existing collection after compression is turned on that existing collection.
 
 Single threaded application - issues **5000** (controlled by argument --batch-size) updates serially in a _round_, and sleeps for **60** (controlled by argument --wait-period) seconds before starting next _round_.
 
-Status of the updates are maintained in database **tracker_db** - for each collection there is a tracker collection named **<< collection >>__tracker_col**.
+After each batch, the temporary dummy field used to trigger compression is automatically removed from all updated documents. Use `--skip-cleanup` to disable this behaviour.
 
-The application can be restarted if it crashes and it will pick up from last successful _round_ based on data in **<< collection >>__tracker_col**.
+Status of the updates are maintained in database **tracker_db** - for each collection there is a tracker collection named **<< collection >>__tracker_col**. Each tracker entry includes a `cleanupComplete` flag indicating whether the dummy field was removed for that batch.
 
-The update statements use field **6nh63** (controlled by argument --update-field), for triggering compression on existing records.
+The application can be restarted if it crashes and it will pick up from last successful _round_ based on data in **<< collection >>__tracker_col**. On successful completion the tracker collection is automatically dropped, as it is no longer needed.
+
+The update statements use field **6nh63** (controlled by argument --update-field), for triggering compression on existing records. This field is removed from each document after compression is applied unless `--skip-cleanup` is set.
 
 The application uses **_id** field for tracking and updating existing documents. If you are using a custom value _id, the value should be sort-able.
 
@@ -24,7 +26,7 @@ cd amazon-documentdb-tools/operations/document-compression-updater
 ## Usage/Examples
 
 ```
- python3 update_apply_compression.py --uri "<<documentdb_uri>>"  --database <<database>>   --collection <<collection>> --update-field << field_name >> --wait-period << int >>> --batch-size << int >>
+ python3 update_apply_compression.py --uri "<<documentdb_uri>>"  --database <<database>>   --collection <<collection>> --update-field << field_name >> --wait-period << int >> --batch-size << int >>
 ```
 
 The application has the following arguments:
@@ -40,4 +42,6 @@ Optional parameters
  --update-field                                 Field used for updating an existing document. This should not conflict with any fieldname you are already using
  --wait-period                                  Number of seconds to wait between each batch
  --batch-size                                   Number of documents to update in a single batch
+ --append-log                                   Append to existing log file instead of overwriting it on startup
+ --skip-cleanup                                 Skip removing the dummy field after each batch (leaves update field permanently on documents)
 ```