On Wed, Dec 18, 2019 at 10:18 AM Simon Riggs <si...@2ndquadrant.com> wrote: > This was my first concern when I thought about it, but I realised that by > taking a snapshot and then calculating xmin normally, this problem would go > away.
Why? As soon as a transaction aborts, the TOAST rows can be vacuumed away, but the READ UNCOMMITTED transaction might've already seen the main tuple. This is not even a particularly tight race, necessarily, since for example the table might be scanned, feeding tuples into a tuplesort, and then the detoating might happen further up in the query tree after the sort has completed. -- Robert Haas EnterpriseDB: http://www.enterprisedb.com The Enterprise PostgreSQL Company
