On Sat, Mar 2, 2019 at 4:38 PM Tomas Vondra <tomas.von...@2ndquadrant.com> wrote: > FWIW I don't think this qualifies as torn page - i.e. it's not a full > read with a mix of old and new data. This is partial write, most likely > because we read the blocks one by one, and when we hit the last page > while the table is being extended, we may only see the fist 4kB. And if > we retry very fast, we may still see only the first 4kB.
I see the distinction you're making, and you're right. The problem is, whether in this case or whether for a real torn page, we don't seem to have a way to distinguish between a state that occurs transiently due to lack of synchronization and a situation that is permanent and means that we have corruption. And that worries me, because it means we'll either report bogus complaints that will scare easily-panicked users (and anybody who is running this tool has a good chance of being in the "easily-panicked" category ...), or else we'll skip reporting real problems. Neither is good. -- Robert Haas EnterpriseDB: http://www.enterprisedb.com The Enterprise PostgreSQL Company
