Excerpt:
SQLite version 3.7.0 is a major new release of SQLite that features a new transaction control mechanism using a write-ahead log or WAL. The traditional rollback-journal is still used as the default so there should be no visible change for legacy programs. But newer programs can take advantage of improved performance and concurrency by enabling the WAL journaling mode.
SQLite version 3.7.0 also contains some query planner enhancements and a few obscure bug fixes, but the only really big change is the addition of WAL mode.
