[CASSANDRA-20092] SSTableScanner can be vastly simplified for compaction

• Type: Improvement
• Status: Patch Available
• Priority: Normal
• Resolution: Unresolved
• Component/s: Local/Compaction
• Change Category: Performance
• Complexity: Normal
• Platform: All

Test and Documentation Plan

Existing tests exercise the new code, with some updates to scanner-specific tests to test both simple and full-fledged scanners.

• Assignee: Branimir Lambov
• Reporter: Branimir Lambov

Authors

Branimir Lambov

• Created: 2 days ago 10:48
• Updated: Yesterday 13:23

Description

One of the main bottlenecks for compaction performance is its use of the SSTableScanner class, whose main purpose is to implement partition range queries and as such supports filtering by row and column that is not helpful to compaction. To implement the latter it must rely on the sstable's index, adding a lot of complexity and inefficiency.

Implementing a simpler version of a scanner that reads off the data file directly for given spans of offsets would speed up compaction significantly.

Issue Links

• Dependent: CASSANDRA-18802 Extend compaction interfaces to provide split points at operation start
• links to: Pull request