Greetings, * Thorsten Schöning (tschoening@xxxxxxxxxx) wrote: > Guten Tag Scott Ribe, > am Freitag, 23. Juli 2021 um 20:07 schrieben Sie: > > > Because it is in the file. WAL can re-do changes, it cannot undo them. > > But isn't visibility of rows associated to transaction numbers as > well? I would have expected the transaction number for the row in B > simply not being available, because it was never part of the WALs up > to and including pg_stop_backup when not following the official > ordering of commands. So I expected that row to simply not be visible > at all and vacuumed at some point or whatever. The information about what transactions have committed and what haven't isn't just in the WAL- it's in the tuple header for frozen tuples, or all visible tuples, and it's in the transaction log files otherwise, so it would depend on when those are copied. Thanks, Stephen
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