Advanced Search: Optimize Group-level Searches for Merge Requests

Overview

Searches that are across entire groups can be slow if the Group has a large number of projects. This is because the query will contain all the project IDs that are part of the selected group.

Adding the Group Hierarchy in the indexed document will allow for the query to specify the group level as a filter and keep eliminate the need to have a large list of project IDs included in the query.

Proposal

This proposal originally contained using traversal_ids in the query, but that can be taken care of in the blocked issue #491211. The proposal for this issue will only contain adding and populating traversal_ids field

• Add traversal_ids to Merge Request index mapping MR example
• Backfill traversal_ids for Merge Request MR example