We seem to be storing the additional metadata at each visit, but like favicons this is data that doesn't change often (if at all), thus most of the times we are just overwriting the same identical data. I'd like us to store new metadata only if it changed.

Comment on attachment 8932141 [details] Bug 1420571 - Don't write unchanged page metadata to places.sqlite. https://reviewboard.mozilla.org/r/203172/#review209220 It's been a while, but I'm guessing .affectedRows isn't used due to intermittents because who knows what query might happen to jump in between an UPDATE and test check? https://searchfox.org/mozilla-central/search?q=affectedRows

We cannot trust affectedRows in connections that can be used on 2 threads, because the other thread could touch it before we read it. We can trust it only on single-threaded connections, thus potentially it could be usable in Sqlite.jsm IF the connection is not a wrapped one.

Pushed by mak77@bonardo.net: https://hg.mozilla.org/integration/autoland/rev/7c7c4ab0020a Don't write unchanged page metadata to places.sqlite. r=Mardak