For reasons, I'm trying to work out just how much undo any single query generates.

I know how to get this in Oracle DB, but don't know if it's possible in MariaDB/MySQL.

Is it possible, and how?

MariaDB 10.6.

1 Answer 1


Your Question is rather general., So here is a rather general Answer: A copy of each modified row is saved for Undo.

  • It's general yes, but it is a general question. Given any query that I can run, is it possible to identify the volume of undo that it has generated? Jan 5 at 10:44
  • @PhilSumner - I don't think there is any metric, at least not any reliable metric. For example, watching disk space is unreliable because each extra row copy will usually fill in free space; only occasionally will it do a block split, thereby consuming 16KB.
    – Rick James
    Jan 6 at 1:50

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