
SELECT * can be very bad, Postgres 9...  - craigkerstiens
https://community.jivesoftware.com/community/developer/blog/2013/01/25/select-can-be-very-bad-postgres-92-index-only-scan-can-be-very-good
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lewispollard
I understand that this is about the use of index-only scans more than
anything, but I think the example is a bad one, because surely you would do a
COUNT rather than a SELECT to get a follower count. Can't think of many
situations where you'd want to load all of the 'follower' data at once,
especially as you'd likely use pagination and lots of caching for actually
displaying users anyway.

