Why Migration and HA Are the Same Conversation Migrating a database and keeping it highly available afterward aren't two separate projects — they're the same discipline applied at two different moments. Both come down to the same underlying mechanism: PostgreSQL's write-ahead log (WAL) , the record of every change made to the database, streamed to wherever it needs to go — a standby replica for HA, a target server for migration, or a backup archive for disaster recovery. This is a granul...