Re: pg_upgrade 13.6 to 15.1?

On Sun, 15 Jan 2023 15:59:20 -0500 Tom Lane wrote:

>pf(at)pfortin(dot)com writes:
>> On Sun, 15 Jan 2023 14:47:35 -0500 Tom Lane wrote:
>>> I think you misunderstand how this is supposed to work. The -D
>>> argument should point at an *empty* data directory that has been
>>> freshly initialized with the new version's initdb. pg_upgrade then
>>> transfers data into that from the old database (-d argument).
>
>> I was hoping to avoid the hours worth of copying to the NVMe SSD.
>> The instructions refer to upgrading with --link; would that save the copy
>> time?
>
>Yes, but to use --link you must have both data directories on the
>same filesystem, so this is still the wrong thing.
>
>Try something like

My understanding:
> mv /mnt/work/var/lib/pgsql/data /mnt/work/var/lib/pgsql/data13
- renames the DB

> initdb /mnt/work/var/lib/pgsql/data
- creates new DB

> pg_upgrade ... -d /mnt/work/var/lib/pgsql/data13 -D /mnt/work/var/lib/pgsql/data --link ...
- if this only creates hard links; then this should do what I want.
My big concern was due to the DB being about 65% of /mnt/work; so doing
it on the same file system absolutely requires hard links vs copying...

Looks like this is what I was trying to be certain of... Thanks!!
Pierre

> regards, tom lane
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