mod-inventory-storage upgrade from Juniper-Kiwi unacceptable

As part of validating Kiwi release, we upgraded a tenant from Juniper-hotfix-3 to Kiwi and the total time for the upgrade was 9.5hrs which is an unacceptable downtime to live libraries. On digging further into logs - this specific call took ~9 hrs

32021-11-20T15:41:38.877Z15:41:38 [] [] [] [] INFO PostgresClient trying to execute: {} UPDATE instance SET jsonb = jsonb_set(jsonb, '{publicationPeriod}', parse_publication_period(jsonb)) WHERE jsonb->>'publicationPeriod' IS NULL AND parse_publication_period(jsonb) IS NOT NULL;

42021-11-21T00:25:48.942Z00:25:48 [] [] [] [] INFO PostgresClient Successfully executed UPDATE instance SET jsonb = jsonb_set(jsonb, '{publicationPeriod}', parse_publication_period(jsonb)) WHERE jsonb->>'publicationPeriod' IS NULL AND parse_publication_period(jsonb) IS NOT NULL;

Attached are the complete mod-inventory-storage upgrade logs in case they are helpful.

Install endpoint timestamps for upgrade - 

Upgrade timestamp from install endpoint:

"startDate": "2021-11-20T15:24:54.006525Z",

"endDate": "2021-11-21T00:58:23.563944Z",

Versions of mod-inventory-storage:

From: mod-inventory-storage-21.0.9

To: mod-inventory-storage-22.0.2

Volume of Inventory data for this tenant:
No. of instances: 10,765,224

No. of items: 12,765,791

No. of holdings_records: 11,789,778

8xlarge DB instance was used for the upgrade

Actual Results:
Time to upgrade mod-inventory-storage from Juniper-Kiwi is ~9hrs for mod-inventory-storage

Expected Results:

Total upgrade time for all modules should be less than 2 hours.