Skip to content

Vector Index Replication

Vector Index Replication is available only in AkasicDB Enterprise Edition and is not supported in Community Edition. AkasicDB writes vector index changes as custom write-ahead log (WAL) records. Use PostgreSQL procedures to configure physical replication and create base backups.

Check Custom WAL

vectoron.custom_wal_enabled controls custom WAL recording. The default is on, and the setting is applied when the server starts.

SHOW vectoron.custom_wal_enabled;

Restart the PostgreSQL server after changing the setting.

ALTER SYSTEM SET vectoron.custom_wal_enabled = 'on';

The installation package or postgresql.conf can override the value. Check it independently on the primary and standby.

When Custom WAL Is Disabled

Primary writes continue when vectoron.custom_wal_enabled = off. Vector index changes made in this state may not be recovered during crash recovery or standby replay.

Enabling custom WAL again does not recover changes from the disabled period. To resume physical standby operation, create a new base backup from the primary and rebuild the standby.

Supported Indexes

Flat, IVF, HNSW, Vamana, and Sparse Inverted Index support custom WAL replay. DiskANN, which is available in Enterprise Edition, does not support physical replication refresh, replay, or promotion.

Do not use a DiskANN index in a deployment that requires a physical standby.

Operational Checks

  • Verify that vectoron.custom_wal_enabled is on on both the primary and standby.
  • Before running a vector index query on a standby, verify that replay and index open have completed.
  • After promotion, verify vector index writes and queries.
  • Do not reuse an existing standby if custom WAL was disabled during its lifetime.