redpanda-data
Add message count on topics list and detail
The estimated number of messages (watermark delta) should be added on the topic list for each topic, as well as on the topic detail (at the top), which should give users a better overview.
Message count in detail view is done. Showing it for all topics might be somewhat expensive though (in terms of performance)
For 'delete' topics: easy For 'compact' topics: exact count would be too expensive, but we can do a few random samples in the topic to compute an average message size, then use the used disk size to get an estimation.
Data should be cached on each node and updated every ~10min.
The numbers not being completely accurate is not an issue if the numbers are prefixed with an ≈, and a tooltip stating that the data is up to X minutes old.
The main intent behind this and is to just get a rough idea anyway, so this approach should definitely be good enough.
Discussed, we don't want to do this on the topic list -- very request-intensive, and still not accurate for compacted topics We have this in topic detail
