MemWAL Index

The MemWAL Index is a system index that serves as the centralized structure for all MemWAL metadata. It stores configuration (shard specs, indexes to maintain), SSTable compaction progress, and shard state snapshots.

A table has at most one MemWAL index. The table may be a primary-key table or an append-only table without primary-key metadata. Primary-key-dependent lookup and deduplication semantics only apply when a primary key is defined.

For the complete specification, see:

• MemWAL Index Overview - Purpose and high-level description
• MemWAL Index Details - Storage format, schemas, and staleness handling
• MemWAL Implementation - Implementation details and expectations