[CASSANDRA-16986] DROP Table should not recycle active CommitLog segments

• Type: Improvement
• Status: Resolved
• Priority: Low
• Resolution: Fixed
• Fix Version/s: 3.0.26, 3.11.12, 4.0.2, 4.1-alpha1, 4.1
• Component/s: Local/Commit Log
• Change Category: Code Clarity
• Complexity: Normal
• Platform: All

Source Control Link

https://github.com/apache/cassandra/commit/35446dca270ba570c5e523fd80ea5c223dfbeccc

Test and Documentation Plan

n/a (change is just additional JavaDoc for a method)

• Assignee: Alex Sorokoumov
• Reporter: Alex Sorokoumov

Authors

Alex Sorokoumov

Reviewers

Caleb Rackliffe

• Created: 23/Sep/21 09:24
• Updated: 27/May/22 19:25
• Resolved: 04/Oct/21 20:20

Description

Right now, DROP TABLE recycles all active CL segments and explicitly marks intervals as clean for all dropping tables. I believe that this is not necessary.

Recycling of CL segments was introduced in CASSANDRA-3578. Back then, it was necessary to recycle all active segments because:
1. CommitLog reused old segments after they were clean. This is no longer the case, I believe, since CASSANDRA-6809.
2. CommitLog segments must have been closed and recycled on DROP TABLE to avoid resurrecting data if a table with the same name is created. This was an issue because tables didn't have unique ids yet (CASSANDRA-5202).

Given that DROP TABLE triggers flush, which in turn cleans CL intervals in Keyspace#unloadCF, I think that we can avoid the call to forceRecycleAll there.