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help / color / mirror / Atom feedFrom: Adrian Klaver <[email protected]>
To: Dimitrios Apostolou <[email protected]>
To: [email protected]
Subject: Re: Performance issues during pg_restore -j with big partitioned table
Date: Wed, 2 Apr 2025 10:45:29 -0700
Message-ID: <[email protected]> (raw)
In-Reply-To: <[email protected]>
References: <[email protected]>
<[email protected]>
On 4/2/25 10:39 AM, Adrian Klaver wrote:
>
> --clean will drop the object entirely not TRUNCATE.
>
> I'm guessing that this is being done by you per:
>
> https://www.postgresql.org/message-id/53760c70-4a87-a453-9e02-57abc9cb2e54%40gmx.net
>
> "After each failed attempt, I need to issue a TRUNCATE table1,table2,...
> before I try again. "
Oops, forgot to engage brain.
From pg_backup_archiver.c:
* In parallel restore, if we created the table earlier in
* this run (so that we know it is empty) and we are not
* restoring a load-via-partition-root data item then we
* wrap the COPY in a transaction and precede it with a
* TRUNCATE. If wal_level is set to minimal this prevents
* WAL-logging the COPY. This obtains a speedup similar
* to that from using single_txn mode in non-parallel
* restores.
*
* We mustn't do this for load-via-partition-root cases
* because some data might get moved across partition
* boundaries, risking deadlock and/or loss of previously
* loaded data. (We assume that all partitions of a
* partitioned table will be treated the same way.)
>
>>
>
>>
>> Thanks in advance,
>> Dimitris
>>
>>
>
--
Adrian Klaver
[email protected]
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Subject: Re: Performance issues during pg_restore -j with big partitioned table
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