We are planning to Archive & Purge our case type instances to improve performance as database tables size are increasing a lot impacting system performance.

We are running a POC in Dev environment to archive & purge some case type instances to see how it goes and how it works. While going through the PDN documentation related to Archive & Purge i have come accross with the following statement in the PDN article "Planning your case archiving and purging process" whose link: https://docs-previous.pega.com/system-administration/86/planning-your-case-archiving-and-purging-process

This article says the following:

To check the performance of your archival process (see steps c. and d.), make a cloud change request to add custom indexes to the case type worktable and on the pr_metadata table by using My Support Portal. Include the following index statements to the cloud change request:

Index on the worktable for the case type: (pxobjclass, pyresolvedtimestamp) INCLUDE (pystatuswork, pzinskey) WHERE pxcoverinskey IS NULL    

Index on pr_metadata: (pyisparent, pyarchivestatus) include (pzinskey)

I would like to know why these custom indexes must be added and what are they used for performance check wise perspective?

Regards,

Israel