Flag for synchronous sqlite write.

It's faster when OFF.
Per offline discussion: Yes, we want to have the safe option on by default.
This would be set to False in the name of performance, which would likely only matter on the 1st run of a monitor (where it gobbles up a whole log).
It would be nice if the code was smart about the size of the batches it's processing or whether it's a first run or not and set this parameter accordingly, but it's a nice-to-have rather than a necessity.
Safety first.