[KUDU-2562] Checkpoint highest legal timestamp in tablet superblock when tablet history GC deletes data

• Type: Improvement
• Status: Open
• Priority: Minor
• Resolution: Unresolved
• Affects Version/s: 1.7.1
• Component/s: tablet
• Assignee: Unassigned
• Reporter: Mike Percy
• Created: 30/Aug/18 18:02
• Updated: 14/Sep/18 20:02

Description

Checkpoint the highest legal timestamp in the tablet superblock when tablet history GC deletes data so that increasing the AHM age doesn’t expose us to inconsistent scans after a GC.

This is a real edge case and is a temporary condition depending on users restarting with a changed configuration flag. However without this safety feature, users can get bad scans if they increase the --tablet_history_max_age_sec command-line flag after a GC operation runs.