[SQLBagOStuff] DBError: Database is read-only: This wiki is currently read-only.

I imagine this is to be expected when updating wikis, as we set the wiki to read only before doing the update.

I wonder if the other errors are also due to updating wikis, given that they happened at the same time. @Tarrow had the idea that in the future we could prevent any traffic going to wikis while we are updating.

From what I can see:

"[SQLBagOStuff] SqlBagOStuff::handleDBError: ignoring connection error"

I only see occurrences of this around the node rollover on Monday morning.

"[SQLBagOStuff] SqlBagOStuff::handleDBError: ignoring query error"

and

[SQLBagOStuff] DBError: Database is read-only: This wiki is currently read-only.

I see very closely paired together in time. As I understand it we we see is:

• We can't write the the SQLBagOStuff so we get DBError: Database is read-only: This wiki is currently read-only.
• the SQLBagOStuff tells us that it is ignoring this error with ignoring query error

So I think we can "ignore this". We could prevent this from happening by showing partially updated Wiki's a waiting page and not sending traffic to them.

Did we do update skirmish on 3/12?

In Conclusion:
These warnings and errors appear when we put wiki in read-only mode for update. First wave of errors was on 3/12, same day we updated Adam's wiki (see https://phabricator.wikimedia.org/T411634#11428737)
We can ignore these.