Note that _without_ BATCH_ATOMIC_WRITE mode, rollback journals result Transaction involves multiple journals), the choice of _journal_modeĭoesn't much matter but TRUNCATE or PERSIST have fewer CGO calls. The SQLite pager's dirty page cache spills to disk, or because the This arrangement allows SQLite toīy-pass writing a rollback journal altogether in almost all cases,Īnd page mutations are written only once to the RocksDB WAL (reducingįor remaining cases where a rollback journal is required (eg, because Where SQLITE_BATCH_ATOMIC_WRITE is enabled, the Store VFS presents itselfĪs a supporting file system, with atomic write semantics implementedīy a RocksDB WriteBatchWithIndex. Logs, to ensure a tighter recovery playback horizon. This implementation detects and maps these operations into new recorded PERSIST and TRUNCATE, which cause a log file to be re-used indefinitely: SQLite provides multiple 'journal_mode' settings, such as Transaction logs (SQLite journals & the WAL) are directly recorded into the Distinct databasesĪre tracked as distinct column families of a single RocksDB. Stores may have multiple associated SQLite databases: a primary database,Īnd arbitrary secondary databases ATTACH'd to the primary. RocksDB compactions will eventually discard old versions of pages that have This adds some overhead to page reads and writes,īut provides a much tighter bound to the recovery playback horizon (since Instance, recorded into the same recovery log, into which page offsets and The database file can thus be thought of as an associative map of page Particularly that reads and writes are always page-aligned, and of page size. SQLite does make certain guarantees with respect to the main database file, Tighten the recovery playback horizon to a more reasonable bound. There must be a means of 'compacting'Īway earlier recorded DB mutations which are no longer needed in order to In an unbounded recovery horizon, as every operation ever done against theĭatabase would need to be replayed. Unbounded lifetime and is read & written randomly by the SQLite engine.ĭirectly representing the main database as a recoverylog.FNode would result SQLite transaction logs are well-suited to this strategy, as they're append. RecoveringĪ database consists of restoring the on-disk representation of the mainĭatabase and associated transaction logs. ( ) with 'hooks' to record mutations of theseįiles made by the database, as they occur, into a recovery log. The central strategy of this package is to provide a SQLite VFS implementation Transactional log files (journals, or write-ahead logs see SQLite records state across a very long lived database file, and short-lived

Package store_sqlite implements the consumer.Store interface via an embedded

Sqlite transaction log