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MySQL has online, non-blocking schema changes since version 5.6. But the underlying data file has to be upgraded to the latest format version for it to work fir
by henrikschroder 11y ago
MySQL has online, non-blocking schema changes since version 5.6. But the underlying data file has to be upgraded to the latest format version for it to work first, and to do that in a non-blocking way on a master server you are probably best off running percona toolkit one first. ALTER TABLE --- FORCE does a data file rewrite.
- Rapzid 11y agoThat's a big "yeah but". You can't rate limit the io. That's huge and the percona tool and LHM offer ways to keep io under control. Along with that you have to pay attention to the live schema update matrix in the docs; many things will upgrade with out locking but require copying the table and this will blast your IO. In addition even with the tools some changes require exclusive table locks. It needs it for a short period of time but if it can't get it because of a long running transaction , queue of transactions, and etc it can block everything up.