We have some questions about the "synchronous" pragma and how it should work in version 3.0. Feedback from the user community is welcomed.
First some review:
The synchronous pragma determines how agressive SQLite is about making sure data really reaches the surface of the disk drive as opposed to just being stored in the operating systems filesystem cache. There are three possible settings:
PRAGMA synchronous=off; PRAGMA synchronous=on; PRAGMA synchronous=full;
When synchronous is OFF, no effort is made to flush data to the disk. This means an unexpected power loss or an OS crash can corrupt the database. When synchronous is ON, data is flushed to disk at key points so that the database is (usually) safe from corruption during a power loss. FULL synchronous does some additional disk flushes in order to guard against a race condition that can lead to database corruption following a power failure on unjournalled filesystems.
Generally speaking, writes happen faster when synchronous is OFF, but at the price of a serious risk of database corruption following a power failure. ON is a little faster than FULL, but not by much. Most users will not notice the difference between ON and FULL.
There are actually two synchronous pragmas. The normal "synchronous" pragma only effects the current session. When the database is reopened, the synchronous setting reverts to what it was. A second "default_synchronous" pragma changes the synchronous setting persistently.
QUESTION 1: The default setting in version 2.8 is ON. For version 3.0 we propose to change the default synchronous setting to FULL. Does anybody have any problems with this?
QUESTION 2: We propose to eliminate default_synchronous and have the regular synchronous pragma change the synchronous setting persistently. Does anybody have any problems with this?
-- D. Richard Hipp -- [EMAIL PROTECTED] -- 704.948.4565
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