What is WAL file in SQLite?

What is a WAL file?

The write-ahead log or "wal" file is a roll-forward journal that records transactions that have been committed but not yet applied to the main database. Details on the format of the wal file are describe in the WAL format subsection of the main file format document.

What is the WAL property?

In computer science, write-ahead logging (WAL) is a family of techniques for providing atomicity and durability (two of the ACID properties) in database systems. The changes are first recorded in the log, which must be written to stable storage, before the changes are written to the database.

How do I set SQLite to WAL mode?

To enable WAL, you can use the SQLite Pragma command:1PRAGMA journal_mode=WAL; In Xojo code, you send the Pragma command to the SQLite DB using the SQLExecute method:2DB.SQLExecute("PRAGMA journal_mode=WAL;") ... 3DB.MultiUser = True. ... 4PRAGMA schema.wal_checkpoint; ... 5DB.SQLExecute("PRAGMA schema.wal_checkpoint;")

How does WAL work?

Briefly, WAL 's central concept is that changes to data files (where tables and indexes reside) must be written only after those changes have been logged, that is, after log records describing the changes have been flushed to permanent storage.