Re: pg_restore scan

PG 17 has integrated zstd compression, while --format=directory lets you do
multi-threaded dumps. That's much faster than a single-threaded pg_dump
into a multi-threaded compression program.

(If for _Reasons_ you require a single-file backup, then tar the directory
of compressed files using the --remove-files option.)

On Tue, Sep 16, 2025 at 10:50 PM R Wahyudi <rwahyudi(at)gmail(dot)com> wrote:

> Sorry for not including the full command - yes , its piping to a
> compression command :
> | lbzip2 -n <threadsforbzipgoeshere>--best > <filenamegoeshere>
>
>
> I think we found the issue! I'll do further testing and see how it goes !
>
>
>
>
>
> On Wed, 17 Sept 2025 at 11:02, Ron Johnson <ronljohnsonjr(at)gmail(dot)com>
> wrote:
>
>> So, piping or redirecting to a file? If so, then that's the problem.
>>
>> pg_dump directly to a file puts file offsets in the TOC.
>>
>> This how I do custom dumps:
>> cd $BackupDir
>> pg_dump -Fc --compress=zstd:long -v -d${db} -f ${db}.dump 2> ${db}.log
>>
>> On Tue, Sep 16, 2025 at 8:54 PM R Wahyudi <rwahyudi(at)gmail(dot)com> wrote:
>>
>>> pg_dump was done using the following command :
>>> pg_dump -Fc -Z 0 -h <host> -U <user> -w -d <database>
>>>
>>> On Wed, 17 Sept 2025 at 08:36, Adrian Klaver <adrian(dot)klaver(at)aklaver(dot)com>
>>> wrote:
>>>
>>>> On 9/16/25 15:25, R Wahyudi wrote:
>>>> >
>>>> > I'm trying to troubleshoot the slowness issue with pg_restore and
>>>> > stumbled across a recent post about pg_restore scanning the whole
>>>> file :
>>>> >
>>>> > > "scanning happens in a very inefficient way, with many seek calls
>>>> and
>>>> > small block reads. Try strace to see them. This initial phase can
>>>> take
>>>> > hours in a huge dump file, before even starting any actual
>>>> restoration."
>>>> > see : https://www.postgresql.org/message-id/E48B611D-7D61-4575-A820-
>>>> > B2C3EC2E0551%40gmx.net <https://www.postgresql.org/message-id/
>>>> > E48B611D-7D61-4575-A820-B2C3EC2E0551%40gmx.net>
>>>>
>>>> This was for pg_dump output that was streamed to a Borg archive and as
>>>> result had no object offsets in the TOC.
>>>>
>>>> How are you doing your pg_dump?
>>>>
>>>>
>>>>
>>>> --
>>>> Adrian Klaver
>>>> adrian(dot)klaver(at)aklaver(dot)com
>>>>
>>>
>>
>> --
>> Death to <Redacted>, and butter sauce.
>> Don't boil me, I'm still alive.
>> <Redacted> lobster!
>>
>

--
Death to <Redacted>, and butter sauce.
Don't boil me, I'm still alive.
<Redacted> lobster!