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What is Write-ahead logs (WAL)?

A type of logs used by storage engine to guarantee transaction ACID. For performance reason, whenever a transaction commits, the storage engine does not changes the data file directly, instead it persists the change by appending it to a log file and then signals the commit success. This process is called write-ahead because the actual change to the data file is batched at a later time, the storage engine just writes ahead to a log file to guarantee that the transaction data persists. If the database crashes in between, the recovery process will redo the changes recorded in the write-ahead logs to apply to the data file, that's why it's also known as redo logs. Another usage for WAL is for change-data-capture (CDC) since it already records all the data changes. e.g. PostgreSQL uses WAL for logical replication.

Safer and faster database change and version control for DBAs and Developers

Bytebase is an open source, web-based database schema change and version control tool for teams. It offers a web-based collaboration workspace to help DBAs and Developers manage the lifecycle of application database schemas.