Persistence Operation Invocation

The Batch operation DataBaseIndexPersist.persistIndex() is executed to perform the backup for all indices. The process for persisting each index is to:-

1. Read current persisted index
2. Read new or modified data from staging table data
3. Generate an in-memory index with 1) + 2) above.
4. Save newly generated in-memory index to the database.
5. Repeat 1) to 4) for each search service.