Re: RDS restore failed due to WAL log and disk space-- any tidy fixes?

It does. I think it uses WAL behind the scenes. In RDS unfortunately cannot
set wal_level, but you can set archive_mode.

On Sun, Nov 17, 2024 at 9:21 AM Ron Johnson <ronljohnsonjr(at)gmail(dot)com> wrote:

> Doesn't RDS have its own replication?
>
> Anyway, for pg_restore, I'd absolutely set archive_mode=off
> and wal_level=minimal, then set them to their production values when it's
> finished.
>
> On Sun, Nov 17, 2024 at 12:12 PM Wells Oliver <wells(dot)oliver(at)gmail(dot)com>
> wrote:
>
>> Interesting. I am migrating a pg_dump archive to a new server, in a
>> single go. Does it make sense to disable (or speed up?) WAL archiving
>> during the restore, then reenable it after the restore so a future replica
>> could work? What would be the steps here? Would disabling or "speeding up"
>> be faster?
>>
>> max_slot_wal_keep_size is -1 at the moment so I think that's why it kept
>> a ton of WAL and ran out of space.
>>
>> On Sun, Nov 17, 2024 at 7:41 AM Laurenz Albe <laurenz(dot)albe(at)cybertec(dot)at>
>> wrote:
>>
>>> On Sat, 2024-11-16 at 16:33 -0800, Wells Oliver wrote:
>>> > I provisioned an RDS instance with 2500GB space and began the restore
>>> of a database I know to be about 1750 GB using 16 jobs.
>>> >
>>> > Unfortunately, it died very near the end when it ran out of disk space
>>> due to WAL log usage. Lots of:
>>> >
>>> > 2024-11-17 00:07:09 UTC::@:[19861]:PANIC: could not write to file
>>> "pg_wal/xlogtemp.19861": No space left on device
>>> >
>>> >
>>> > And then kaboom.
>>> >
>>> > I'm wondering what my course of action should be. Can I disable/reduce
>>> WAL during a restore?
>>> > wal_level is set to replica, can this temporarily be set to minimal?
>>> Should I just eat the extra
>>> > costs to add headroom for the WAL? Would using fewer jobs during a
>>> restore reduce the amount of WAL
>>> > created?
>>>
>>> If you are using minimal WAL logging and you restore the dump in a
>>> single transaction, you
>>> should see way less WAL generated, because data inserted into the table
>>> in the same transaction
>>> as the CREATE TABLE statement need not be WAL logged.
>>>
>>> But you might more easily solve the problem by speeding up or disabling
>>> the WAL archiver,
>>> so that PostgreSQL removes old WAL after the next checkpoint.
>>>
>>> Yours,
>>> Laurenz Albe
>>>
>>
>>
>> --
>> Wells Oliver
>> wells(dot)oliver(at)gmail(dot)com <wellsoliver(at)gmail(dot)com>
>>
>
>
> --
> Death to <Redacted>, and butter sauce.
> Don't boil me, I'm still alive.
> <Redacted> lobster!
>

--
Wells Oliver
wells(dot)oliver(at)gmail(dot)com <wellsoliver(at)gmail(dot)com>