October 25, 2014

Give feedback on a pt-online-schema-change update

I am writing a specification for updating pt-online-schema-change. The outline of the changes I want to make is here: http://www.percona.com/docs/wiki/ptdev:blueprints:redesign-pt-online-schema-change

The idea is to make the tool Do The Right Thing, with features such as automatically throttling its operation to avoid causing replicas to lag. Many of the features and improvements are similar to those added to the newly rewritten pt-table-checksum.

If you have any comments on it, please write to the mailing list with your suggestions. Thanks!

About Baron Schwartz

Baron is the lead author of High Performance MySQL.
He is a former Percona employee.

Comments

  1. Guy Nir says:

    Hi
    Very interesting and important changes, I have faced some of the problems with the pt-online-schema-change which are:

    – Primary Key with multiple fields is not supported in OSC – I cannot see any plan to fix this, are there plans for future change ?
    – Column names in quotes – as we have reserved words as column names, it will be good to have the col name in quotes inside the osc, which will allow altering a table without restrictions of col names.

    I have also seen you have addressed the Sleep time problem (with –max-lag parameter), for which we have worked around by allowing the sleep time to be dynamically changed via a file.
    will this also handle the part of rolling forward of changes of a table in chunks with sleep ? this cause a huge replication delays with no sleep option in between (now I set the lag to be very high just before the new table

  2. The new version will fix all of those problems. You can look at the new code here: https://code.launchpad.net/~percona-toolkit-dev/percona-toolkit/pt-osc-2.1.1 Note that it is still work-in-progress, so it’s probably not ready to use yet.

  3. Nicolas V says:

    Hi,
    First, thanks for all these great tools :), I discover MySQL for only 2 monthes (previously I was PostgreSQL DBA), and PerconaTools is already my must-have !

    Now my question about pt-online-schema-change, could it be possible to drop all indexes before copying the data, then recreate all indexes after ?
    With InnoDB and the fast index creation, it will be much faster. I run few test, and it’s about 3 time faster.

  4. It is something we have noted as a future enhancement.

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