Re: Making pg_rewind faster

Hi,

I've attached an updated version of the patch against master with the changes
suggested.

On Tue, Nov 29, 2022 at 10:03 PM Michael Paquier <michael(at)paquier(dot)xyz> wrote:
>
> On Thu, Oct 06, 2022 at 04:08:45PM +0900, Michael Paquier wrote:
>>
>> There may be something I am missing here, but there is no need to care
>> about segments with a TLI older than lastcommontliIndex, no?

Hard to say. pg_rewind is intended to make the same "copy" of the cluster which
implies pg_wal/ should look the same. There might be use cases around logical
replication where you would want these WAL files to still exist even
across promotions?

>> decide_wal_file_action() assumes that the WAL segment exists on the
>> target and the source. This looks bug-prone to me without at least an
>> assertion.

From previous refactors there is now an Assertion in filemap.c
decide_file_action that handles this.

> Assert(entry->target_exists && entry->source_exists);

decide_wal_file_action is called after the assertion.

Thanks,

--
John Hsu - Amazon Web Services