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I have a huge table that is being actively written & i need to perform a update to the table to change a column from medium blob to long blob. I am not sure if its an inplace upgrade i.e. will the column content be rewritten from medium blob to long blob or if long blob can read content from the medium blob. While reading Blob and Storage Requirement, I am guessing that the column content will be rewritten as long blob needs 1 extra byte compared to medium blob.

Please suggest if its the case or do you suggest using pt-online-schemachange script from percona to do the conversion. FYI i am running 5.7 and 8.0 in various environments that need this change

S Kr
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  • This structure change (change column datatype) allows only `ALGORITHM=COPY`. – Akina Dec 02 '20 at 16:36
  • Please elaborate on what you mean. What I effectively need is ALGORITHM=INPLACE & LOCK=NONE if i don't need to go into a maintenance window? – S Kr Dec 02 '20 at 17:14
  • https://dev.mysql.com/doc/refman/8.0/en/innodb-online-ddl-operations.html#online-ddl-column-operations – Akina Dec 02 '20 at 17:22

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