[seppo0010]

The data is written twice when using WAL. From the same link you pasted:

> The original content is preserved in the database file and the changes are appended into a separate WAL file.

The difference is whether the journal keeps the new data (WAL) or the old data (not WAL). If you are writing big chunks of data, WAL will probably be more I/O intensive.

Taking a wild guess I'll say that if you are adding data to the database, and not using WAL, the data will only be written once since the journal won't keep a reference to old data if no pages is being overwritten.

[tines]

Ah, I see the difference now, thanks.