Read perf would be good in isolation, sure; but what about the lock contention over those rows due to the frequent writes to the tags column? Usually "taggings"

Read perf would be good in isolation, sure; but what about the lock contention over those rows due to the frequent writes to the tags column? Usually "taggings" have a much higher rate-of-change than the objects they tag. If you're not at least keeping a thing_taggings has-one table (thing bigserial, tags intarray) separate from your things table, I could see this degrading performance for any query that wants to touch the table.