I want to use the Write-Ahead Logging feature of SQLite in a j2se program. Please help me with a java implemention example.
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1 Answer
You need to execute a Sqlite specific command (just like you'd execute other SQL queries):
pragma journal_mode=wal
For the specifics of using this pragma, please read http://www.sqlite.org/pragma.html#pragma_journal_mode
Here are some highlights:
- Your Sqlite library must be >= 3.7.0.
- This journal_mode is persistent (or sticky), ie you'll need to disable it explicitly if you want to access your database with a < 3.7.0 Sqlite.
5 Comments
seh
Note that this command will return a result set -- a detail missed in the Xerial SQLite JDBC wrapper, as reported here: code.google.com/p/sqlite-jdbc/issues/detail?id=7
Vivek
@sixfeetsix: Does this means that i have to write a statement like stmt.execute("pragma journal_mode=WAL"); in my java program ? But i don't see any increase in performance with this statement.
@sam: yes, execute the statement as any other sql; as seh mentions, this pragma is particular as it returns a result set with the resulting journal_mode, so please make sure you get "wal". If you do get "wal", then I guess using WAL wasn't what ou needed to do to increase performance. If you want help with that, I suggest you create a new question where you'll describe what it is that is slow by providing the enough context to allow the community to help you (eg how much time a query takes, what is the query, what is/are the table structure(s), a sample of the typical records, etc.)
Vivek
@sixfeetsix: The problem is "pragma journal_mode=WAL" is supported by SQLite 3.7 but there are no compatible jdbc drivers for this new version and the default mode does not changing through older drivers.
@sam: doesn't the workaround in code.google.com/p/sqlite-jdbc/issues/detail?id=7 work for you?