Table modifications are a common task for database
administrators. In this blog, I’ll explain how to alter tables
online in a controlled manner that does not disrupt application
users or cause application downtime.
One of the tools in Percona Toolkit is pt-online-schema-change, a utility that alters
the structure of a table without interfering with the reads or
writes. The tool creates an empty copy of the table to alter and
modify as desired before copying the rows from the original table
into the new one.
When the copying is finished, it removes the original table and
replaces it with the new one. Any changes made to data in the
original tables during the copy process will be reflected in the
new table as the tool creates triggers on …
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