Re: q re removal/recycling of WAL files

On Wed, 2021-11-03 at 16:24 -0600, Scott Ribe wrote:
> Let's say that there's a big update as part of a migration, and that update times out,
> and the migration utility retries it several times. (Context is that sequence happened
> through automated utility, and filled the disk, leading to an unfortunate series of events.)
>
> 1) At what point does WAL from the failed & rolled back operations "go away"? During the next
> checkpoint? During the checkpoint after completion of all other transactions which
> overlapped time-wise with the timing-out ones?

A WAL segment is deleted if it contains no record newer than the latest checkpoint
or the oldest replication slot, and it is archived (if enabled) and "wal_keep_size"
does not require it to be kept around.

That is the same for committed and rolled back operations.

> 2) Is there a chance that never-visible rows would be written into tables, bloating them?

Yes, that will definitely happen.

Yours,
Laurenz Albe
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