[CASSANDRA-1956] Convert row cache to row+filter cache

• Type: Improvement
• Status: Resolved
• Priority: Low
• Resolution: Duplicate
• Fix Version/s: 2.1 beta1
• Assignee: Vijay Assign to me
• Reporter: Stu Hood

Authors

Vijay

Reviewers

Sylvain Lebresne

• Created: 09/Jan/11 10:48
• Updated: 16/Apr/19 12:33
• Resolved: 21/Sep/13 01:37

Description

Changing the row cache to a row+filter cache would make it much more useful. We currently have to warn against using the row cache with wide rows, where the read pattern is typically a peek at the head, but this usecase would be perfect supported by a cache that stored only columns matching the filter.

Possible implementations:

• (copout) Cache a single filter per row, and leave the cache key as is
• Cache a list of filters per row, leaving the cache key as is: this is likely to have some gotchas for weird usage patterns, and it requires the list overheard
• Change the cache key to "rowkey+filterid": basically ideal, but you need a secondary index to lookup cache entries by rowkey so that you can keep them in sync with the memtable
• others?

Issue Links

• duplicates: CASSANDRA-5357 Query cache / partition head cache