How to create custom MongoDB indexes

• I am trying to use ST2 REST API to get executions.
  • The request is as follows:

curl -s \
  -H 'Content-Type: application/json'
  -H "St2-Api-Key: ${ST2_API_KEY}"\
  -k 'localhost:80/api/v1/executions?offset=0&limit=100&parent=null'

• This request takes about 5 to 8 seconds in our environment.

• I checked the mongoDB's execution plan and found that the sorting process took a long time.

• I created a following index to speed up the sorting process.

db.action_execution_d_b.createIndex({ parent: 1, start_timestamp: -1, 'action.ref': 1 }, { background: true })

• The index has improved request speed. However, the created index is automatically deleted.

2024-11-15T03:22:50.069+0900 I ACCESS   [conn965898] Successfully authenticated as principal st2admin on st2 from client xxx.xxx.xxx.xxx:50468
2024-11-15T03:22:50.103+0900 I COMMAND  [conn965898] CMD: dropIndexes st2.action_execution_d_b

• Then I have two questions
  • Is it a specification that user-created index is deleted?
  • Is there a way to prevent user-created index from being automatically deleted?

Start by reproducing the executions request against the action_execution_d_b collection and inspect when the custom parent/start_timestamp/action.ref index is removed. Trace the index-management path associated with the dropIndexes log; the issue is resolved when the behavior is explained and a supported way to preserve the index, or a clearly scoped fix, is identified.