[OAK-3070] Use a lower bound in VersionGC query to avoid checking unmodified once deleted docs

• Type: Improvement
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 1.7.0, 1.8.0
• Component/s: mongomk, rdbmk
• Labels: performance
• Epic Link: DocumentMK revision GC
• Assignee: Marcel Reutegger
• Reporter: Chetan Mehrotra
• Created: 02/Jul/15 17:58
• Updated: 30/May/17 08:38
• Resolved: 09/Mar/17 11:50

Description

As part of OAK-3062 mreutegg suggested

As a further optimization we could also limit the lower bound of the _modified
range. The revision GC does not need to check documents with a _deletedOnce
again if they were not modified after the last successful GC run. If they
didn't change and were considered existing during the last run, then they
must still exist in the current GC run. To make this work, we'd need to
track the last successful revision GC run.

Lowest last validated _modified can be possibly saved in settings collection and reused for next run

Issue Links

• is related to: OAK-5966 Not able to connect in read only mode with old DocumentNodeStore repo
• is related to: OAK-3710 Continuous revision GC
• is related to: OAK-5704 VersionGC: reset _deletedOnce for documents that have been resurrected
• relates to: OAK-3062 VersionGC failing on Mongo with CursorNotFoundException
• relates to: OAK-4780 VersionGarbageCollector should be able to run incrementally