One use of this would be proactively monitoring for large databases like the ones that are being looked at in T132431: labsdb1001 and labsdb1003 short on available space.

A big hammer method for checking user/tool database sizes:

SELECT
    table_schema
  , sum( data_length ) as data_bytes
  , sum( index_length ) as index_bytes
  , sum( table_rows ) as row_count
  , count(1) as tables
FROM information_schema.TABLES
WHERE table_schema regexp '^[psu][0-9]'
GROUP BY table_schema;

Something could run that once per day (or maybe even once a week) aon each distinct database host for labs and log the data in a way that could be used to produce nice timeseries reports.

On 2016-04-21 there are 223 distinct user/tool schemas on tools.labsdb. Other hosts have far fewer (c1=58, c3=35).

https://tools.wmflabs.org/tool-db-usage/ now provides point-in-time database usage information.

I wonder if nowadays all this should be ingested by prometheus and exposed through grafana dashboards instead of implementing specific tools to show each bit of data

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