[CASSANDRA-18216] Allow sharding of the SAI in-memory index

• Type: Improvement
• Status: Triage Needed
• Priority: Normal
• Resolution: Unresolved
• Fix Version/s: 5.x
• Component/s: Feature/SAI
• Labels: SAI
• Epic Link: Storage Attached Indexes (Phase 3)
• Platform: All
• Assignee: Unassigned
• Reporter: Mike Adamson
• Created: 01/Feb/23 16:41
• Updated: 26/Jan/24 19:43

Description

The Memtable implementation allows it to be split into a number of shards. This reduces contention during writes.

The MemtableIndex in SAI should follow this practice. It currently does not support sharding so all writes hit the same synchronized write block. The in-memory index search can also use the sharding to reduce the number of indexes that it searches based on the key range passed to the search.