WAL ModeIntermediate
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sqlWhat is WAL (Write-Ahead Logging) mode in SQLite and why is it superior to rollback journals?
Explanation & Concept
By default, SQLite uses a rollback journal: writes lock out readers entirely while writing back changes.
In **WAL mode** (`PRAGMA journal_mode = WAL;`), changes are appended to a separate `-wal` file. This provides **true concurrency**: readers never block writers, and writers never block readers.
Code Example
sql
-- Enable WAL mode (persists across restarts)
PRAGMA journal_mode = WAL;
-- Set synchronous mode to NORMAL for maximum WAL speed with durability
PRAGMA synchronous = NORMAL;How It Works & Key Takeaways
In WAL mode, multiple processes can read from the base database file while a writer appends to the `-wal` file simultaneously.
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