On Wed, Jun 16, 2021 at 1:21 PM Peter Geoghegan <p...@bowt.ie> wrote: > Oh yeah, I think that I get it now. Tell me if this sounds right to you: > > It's not so much that HeapTupleSatisfiesVacuum() "disagrees" with > heap_prune_satisfies_vacuum() in a way that actually matters to > VACUUM. While there does seem to be a fairly mundane bug in > GetOldestNonRemovableTransactionId() that really is a matter of > disagreement between the two functions, the fundamental issue is > deeper than that. The fundamental issue is that it's not okay to > assume that the XID horizon won't go backwards. This probably matters > for lots of reasons. The most obvious reason is that in theory it > could cause lazy_scan_prune() to get stuck in about the same way as > Justin reported, with the GetOldestNonRemovableTransactionId() bug.
Any update on this, Andres? -- Peter Geoghegan
