Thread: Verify or dump pgdata files

Verify or dump pgdata files

From

Murthy Nunna

Date:

20 October, 05:45:22

Hi,

We are currently using pg_waldump to verify integrity of WAL files after archiving them in external storage. If the WAL is incomplete pg_waldump returns error, which is great.

Similarly, I am wondering if there is any utility that can be used against data files in /pgdata. Just to verify after “rsync” of /pgdata.

Thanks in advance for your response.

Re: Verify or dump pgdata files

From

Muhammad Ikram

Date:

21 October, 09:33:31

Hi,

Could you use diff ? e.g.

diff -qr /var/lib/pgsql/15/data /tmp/data

pg_checksums --verify --data-dir=/pgdata (for checksum enabled databases)

or do checksum on source and target and take diff between two checksum generated files e.g.

cd /pgdata
find . -type f -exec sha256sum {} \; > /tmp/source_checksums.txt

Regards,

Ikram

On Sun, Oct 20, 2024 at 4:45 AM Murthy Nunna <mnunna@fnal.gov> wrote:

Hi,

We are currently using pg_waldump to verify integrity of WAL files after archiving them in external storage. If the WAL is incomplete pg_waldump returns error, which is great.

Similarly, I am wondering if there is any utility that can be used against data files in /pgdata. Just to verify after “rsync” of /pgdata.

Thanks in advance for your response.

RE: Verify or dump pgdata files

From

Murthy Nunna

Date:

21 October, 21:51:44

Hi Muhammad,

Thank you for responding to my query.

I don’t think checksum method will work in my situation because the source file would have changed by the time I run checksum. So, the checksum (or diff) will be different.

I am doing rsync of active cluster.

What I am looking for is physical (structural) verification of target file such as beginning block and end block, beginning of file and end of file etc. All I want to know is “completeness” and “readability” of the file by postgres.

Thanks.

From: Muhammad Ikram <me.mikram@gmail.com>
Sent: Sunday, October 20, 2024 10:34 PM
To: Murthy Nunna <mnunna@fnal.gov>
Cc: pgsql-admin@postgresql.org
Subject: Re: Verify or dump pgdata files

[EXTERNAL] – This message is from an external sender

Hi,

Could you use diff ? e.g.

diff -qr /var/lib/pgsql/15/data /tmp/data

pg_checksums --verify --data-dir=/pgdata (for checksum enabled databases)

or do checksum on source and target and take diff between two checksum generated files e.g.

cd /pgdata
find . -type f -exec sha256sum {} \; > /tmp/source_checksums.txt

Regards,

Ikram

On Sun, Oct 20, 2024 at 4:45 AM Murthy Nunna <mnunna@fnal.gov> wrote:

Hi,

We are currently using pg_waldump to verify integrity of WAL files after archiving them in external storage. If the WAL is incomplete pg_waldump returns error, which is great.

Similarly, I am wondering if there is any utility that can be used against data files in /pgdata. Just to verify after “rsync” of /pgdata.

Thanks in advance for your response.

Re: Verify or dump pgdata files

From

Ron Johnson

Date:

21 October, 22:21:45

Use PgBackRest or pg_basebackup. Not only do they correctly handle wal files, but do checksums.

On Mon, Oct 21, 2024 at 11:51 AM Murthy Nunna <mnunna@fnal.gov> wrote:

Hi Muhammad,

Thank you for responding to my query.

I don’t think checksum method will work in my situation because the source file would have changed by the time I run checksum. So, the checksum (or diff) will be different.
I am doing rsync of active cluster.

What I am looking for is physical (structural) verification of target file such as beginning block and end block, beginning of file and end of file etc. All I want to know is “completeness” and “readability” of the file by postgres.

Thanks.

From: Muhammad Ikram <me.mikram@gmail.com>
Sent: Sunday, October 20, 2024 10:34 PM
To: Murthy Nunna <mnunna@fnal.gov>
Cc: pgsql-admin@postgresql.org
Subject: Re: Verify or dump pgdata files

[EXTERNAL] – This message is from an external sender
Hi,

Could you use diff ? e.g.

diff -qr /var/lib/pgsql/15/data /tmp/data

Or

pg_checksums --verify --data-dir=/pgdata (for checksum enabled databases)

or do checksum on source and target and take diff between two checksum generated files e.g.

cd /pgdata
find . -type f -exec sha256sum {} \; > /tmp/source_checksums.txt

Regards,
Ikram

On Sun, Oct 20, 2024 at 4:45 AM Murthy Nunna <mnunna@fnal.gov> wrote:
Hi,

We are currently using pg_waldump to verify integrity of WAL files after archiving them in external storage. If the WAL is incomplete pg_waldump returns error, which is great.

Similarly, I am wondering if there is any utility that can be used against data files in /pgdata. Just to verify after “rsync” of /pgdata.

Thanks in advance for your response.

Death to <Redacted>, and butter sauce.

Don't boil me, I'm still alive.

<Redacted> crustacean!

Re: Verify or dump pgdata files

From

Alvaro Herrera

Date:

22 October, 00:31:31

On 2024-Oct-19, Murthy Nunna wrote:

> Similarly, I am wondering if there is any utility that can be used
> against data files in /pgdata. Just to verify after "rsync" of
> /pgdata.

Maybe you could use pg_verifybackup for this, assuming you do your
"rsync" with pg_basebackup.

-- 
Álvaro Herrera               48°01'N 7°57'E  —  https://www.EnterpriseDB.com/