On 7/18/23 11:58, Devin Ivy wrote:
> Hi all,
> I'm hoping to ensure I understand the implications of dropping a large
> table and the space being reclaimed by the database and/or OS. We're
> using pg v14.
>
> This table is quite large with a primary key and one additional
> index—all together these are on the order of 1TB. The primary key and
> index take-up quite a bit more space than the table itself. Our hope
> is to discontinue use of this table and then eventually drop it.
> However, the database is under constant load and we'd like to avoid
> (or at least anticipate) downtime or degraded performance. The
> database also replicates to a standby instance.
>
> So in short, what can we expect if we drop this table? Will the
> strategy that pg takes to give that space back to the rest of the
> database and/or OS have significant effects on availability or
> performance? Finally, are there any other considerations that we
> should take into account? I appreciate your time and input, thanks!
>
> --
> Devin Ivy
You might consider deleting portions of the table in separate
(consecutive) batches (maybe 5% per delete). And then truncate table is
not logged so that might be an alternative.