Dear developers,
when reporting features are developed, please consider that software
may be used on a site with millions of rows in tables. Please always
check if indexes can be used for whole report, if not, please
consider avoiding such feature, or consult people with access to
database on #wikimedia-tech. If you actually have access to database,
do not hesitate to EXPLAIN a query on our live datasets and evaluate
costs of operation. Otherwise site goes down or crawls and both users
and operators are frustrated ;-) Remember, less data query needs to
read - faster it is!!!!!! :) And better for performance is when no
data is read, of course ;-)
Thanks,
Domas