Re: Physical replication from x86_64 to ARM64

Aleksander Alekseev <aleksander@timescale.com> writes:
>> Initial experiments show no observable problems when copying PGDATA or in
>> fact using physical streaming replication between the two CPU architectures.

> That's an interesting result. The topic of physical replication
> compatibility interested me much back in 2017 and I raised this question on
> PGCon [1]. As I recall the compatibility is not guaranteed, nor tested, and
> not going to be, because the community doesn't have resources for this.

Yeah.  As far as the hardware goes, if you have the same endianness,
struct alignment rules, and floating-point format [1], then physical
replication ought to work.  Where things get far stickier is if the
operating systems aren't identical, because then you have very great
risk of text sorting rules not being the same, leading to index
corruption [2].  In modern practice that tends to be a bigger issue
than the hardware, and we don't have any good way to check for it.

            regards, tom lane

[1] all of which are checked by pg_control fields, btw
[2] https://wiki.postgresql.org/wiki/Locale_data_changes