#1454 ✓resolved
Greg Campbell

"edge" dm-migrations incompatible with MySQL < 5.1.12

Reported by Greg Campbell | December 9th, 2010 @ 07:20 PM | in 1.1

Commit https://github.com/datamapper/dm-migrations/commit/faea4c2b7a5e03c6... switches from using SHOW VARIABLES to using a select against information_schema.session_variables. According to http://dev.mysql.com/doc/refman/5.1/en/variables-table.html, that table wasn't added until MySQL 5.1, which means that migrations fail against a database server running Debian stable (lenny), which only includes MySQL 5.0.

Comments and changes to this ticket

  • Dan Kubb (dkubb)

    Dan Kubb (dkubb) January 16th, 2011 @ 09:35 PM

    Ok, I will look at this. Our intention is generally to support the latest stable version of a specific database unless someone needs it and the code impact is minimal; which are both the case here.

    The one problem with rolling back is that I don't have a working solution for JRuby without using information_schema.session_variables yet. Currently JRuby support trumps supporting older versions of MySQL in terms of priority, so I won't be changing anything until I can figure out why JRuby behaves differently when using SHOW VARIABLES.

    Once I can figure out a way to use SHOW VARIABLES with JRuby I'll roll back the change, and put in place whatever fix I need for JRuby.

    Absolutely worst case, if there's no way I can figure it out I'll put a logic branch in to use different queries for different versions of MySQL. I really dislike this though, since it means one branch might not get tested as much as another.

  • Greg Campbell

    Greg Campbell January 16th, 2011 @ 11:09 PM

    Thanks, Dan. I'll see what I can do to help; I can certainly maintain my fork for my own use until a solution is reached.

  • Piotr Solnica (solnic)

    Piotr Solnica (solnic) January 19th, 2011 @ 10:25 AM

    well, it's hit me too. I can't auto-upgrade on my staging server where I have mysql 5.0

  • Martin Gamsjaeger (snusnu)

    Martin Gamsjaeger (snusnu) January 20th, 2011 @ 07:08 AM

    • State changed from “unconfirmed” to “confirmed”
  • Dan Kubb (dkubb)

    Dan Kubb (dkubb) January 25th, 2011 @ 05:04 PM

    • State changed from “confirmed” to “resolved”

    (from [3f68c9056e4eda6b8bb0f2c3b015da64b388e30e]) Revert "Use a SELECT query to retrieve the session variable"

    This reverts commit faea4c2b7a5e03c6bbd974589ed6d9bbec8a008b.

    • This commit works-around some problems with JRuby/JDBC returning incorrect results for the previous query. However, if it's truly a bug it should be fixed upstream rather than locally in this code.

    Plus the query I'm using here excludes people using MySQL 5.0 and below, which is not acceptable.

    I (or someone) need to revisit the actual problem with the code I'm about to revert back to under JRuby and try to isolate the cause of the invalid value being returned.

    [#1454 state:resolved] https://github.com/datamapper/dm-migrations/commit/3f68c9056e4eda6b...

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