Firstly, my apologies for the minute and a bit of echo at the start of this video, OBS had somehow magically decided to start recording both the primary mic and the one built into my camera. Easy fix, moving on...
During the livestream, I was perplexed as to why the HIBP DB was suddenly maxing out. Turns out that this aligned with dropping a constraint on the table of domains which appears to have caused the table to reindex and massively slow down the queries for breached email addresses. Further, we simultaneously started having problems related to MAXDOP (the maximum degree of parallelism for the stored procedure running the query), which was only resolved after we forced it to not run on multiple CPUs by setting it to 1 (weirdly, 2 is also fine but 3 or higher completely killed perf). Fun times, running a service like this.
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