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Weekly Report -- 13/05/2016




Made some progress on the InfluxDB memory issues we were having when catching up on old data. Now we are a lot less likely to drive the machine into swap, at the cost of taking a bit longer for backfilled data to be aggregated. Part of the problem was caused by my fix last week for the change in behaviour for the first() and last() aggregation functions in Influx 0.11 -- I've put in a new hacky fix but I'm basically waiting for Influx 0.13 which will hopefully provide us a way to get the old behaviour back.

Found another weird bug in Influx where if we query for certain streams, then sometimes a result row will get split into two "half-rows". This was messing with our querying code in NNTSC which assumes that the database will return only complete rows, so I've had to add extra code to deal with this possibility.

More influx issues: we aren't allowed to perform aggregation on the timestamp column in an Influx table, which was breaking our loss calculation for DNS -- we were using count(timestamp) to determine how many DNS requests we had sent as this was the only non-NULLable column in the DNS data table. Instead, I've had to add an extra "requests" column to the DNS data table so that we have an explicit count available in our aggregated data.

Lots of little fixes on the website. The changes to modals to bootstrap 3.3 are continuing to have a number of interesting flow-on effects, such as the "add new series" modal no longer working after the first time it is used. Added an AS path tab to latency and loss graphs that are only showing a single series, as we've often seen some interesting change and wondering whether the path has changed at the same time. Also fixed an issue where the last datapoint was often not visible on the graphs.

Finally, submitted my unexpected traffic paper to IMC on Thursday. Fingers crossed.