In this mode, only database journal mode will be changed, connection pool
size will still be limited to a single connection.
If enabled, compatibility WAL mode will be used if an app hasn't explicitly
requested journal mode, by calling disable/enableWriteAheadLogging.
Compatibility WAL mode is controlled by debug.sqlite.use_compatibility_wal
property and db_use_compatibility_wal config resource.
Impact on write performance:
On ext4, with WAL, there is approx 300% increase in speed of update operations
On f2fs, with WAL, there is approx 5% increase in speed of update operations
Impact on number of writes:
On ext4, switching to WAL reduces the number of writes by approx 50%.
On f2fs, switching to WAL increases the number of writes by approx 15%.
Test: CtsDatabaseTestCases
Test: manual, running device
Bug: 33044236
Change-Id: Iaffb5651df39d8c9f710d7dbbe174f9c0d8a3186
5bd43ad2e7