[CASSANDRA-18648] Improved DeletionTime serialization

• Type: Improvement
• Status: Resolved
• Priority: Normal
• Resolution: Fixed
• Fix Version/s: 5.0-alpha1, 5.0
• Component/s: Local/SSTable
• Change Category: Performance
• Complexity: Normal
• Platform: All

Source Control Link

https://github.com/apache/cassandra/commit/2a458ba01dae3b35b62ad2ef361e1acb567c97f0

Test and Documentation Plan

See PR and comments

• Assignee: Berenguer Blasi
• Reporter: Berenguer Blasi

Authors

Berenguer Blasi

Reviewers

Branimir Lambov, Jacek Lewandowski, Jakub Zytka, Piotr Kolaczkowski

• Created: 05/Jul/23 04:29
• Updated: 12/Sep/23 13:03
• Resolved: 26/Jul/23 08:49

Description

DeletionTime.markedForDeleteAt is a long useconds since Unix Epoch. But I noticed that with 7 bytes we can already encode ~2284 years. We can either shed the 8th byte, for reduced IO and disk, or can encode some sentinel values as flags there. blerer suggested starting with DeletionTime.LIVE.

That would mean reading and writing 1 byte instead of 12 (8 mfda long + 4 ldts int). Yes we already avoid serializing DeletionTime (DT) in sstables at row level entirely but not at partition level and it is also serialized at index, metadata, etc.

Issue Links

• links to: CASSANDRA-18648-trunk PR
• links to: GitHub Pull Request #2464