How to restore updated records

Hi all.
Sorry for my problem.
I am using pg on ~100 servers fro 5 y. without any problems,
but this time I make a big mistake.

A have a table tasks with about 20000 records.
The table have ID as pk and some other fields.

I typed : update tasks set c1='sss';
instead update tasks setc1='sss' where id=10;

And the pg updated all my table tasks.

I do not have any backup on this table.
Exists any way to restore the data>
After the mistake I stopped to execute any commands to this
database and also I DO NOT HAVE running vacuum, vacuum
analyze ot vacuum full analyze on this table.

I know pg stores the old copy of data, but I do not have any
idea how to restore this deleted records.

Pls., point me to any solution for this problem.

Many thanks and best regards,
ivan.

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