tag:blogger.com,1999:blog-16959946.post637973980638663378..comments2023-12-09T16:44:47.897+01:00Comments on The Data Charmer: Yet another MySQL 5.7 silent changeGiuseppe Maxiahttp://www.blogger.com/profile/15801583338057324813noreply@blogger.comBlogger2125tag:blogger.com,1999:blog-16959946.post-59799627472053241832015-08-04T11:32:15.874+02:002015-08-04T11:32:15.874+02:00@Ivan,
The variable show_compatibility_56 was enab...@Ivan,<br />The variable show_compatibility_56 was enabled by default in MySQL 5.7.6 and 5.7.7. However, in MySQL 5.7.8 it is disabled.<br /><br />The behavior is demonstrated and there is at least one <a href="https://bugs.mysql.com/bug.php?id=77732" rel="nofollow">bug</a> that shows the side effects of this change.<br /><br />If you install both MySQL 5.7.7 and 5.7.8 without any additional options, and try "SELECT variable_name from information_schema.global_variables limit 1" in both versions, you will see the difference.<br /><br />System variables are now part of performance_schema. I was as surprised as you are when I saw them. If you haven't had any contact with MySQL 5.7 and plan to use in the next future, you should really have a serious look at the <a href="https://dev.mysql.com/doc/refman/5.7/en/mysql-nutshell.html" rel="nofollow">new features and changes</a>.<br /><br />Back to the main point: enabling show_compatibility_56 in MySQL 5.7.8 would solve the problem temporarily, but it will hide the rest of the compatibility problems, which will hit you when the deprecation will cause the features to disappear for good.<br /> Giuseppe Maxiahttps://www.blogger.com/profile/15801583338057324813noreply@blogger.comtag:blogger.com,1999:blog-16959946.post-5235287649702506882015-08-04T10:31:27.055+02:002015-08-04T10:31:27.055+02:00Hi GIuseppe,
Thanks for this post, I am still ca...Hi GIuseppe, <br /><br />Thanks for this post, I am still catching up with the latest and this kind of articles help me a lot.<br /><br />I am really confused by the whole story.<br /><br />Googling a bit I found this:<br />http://dev.mysql.com/doc/refman/5.7/en/server-system-variables.html#sysvar_show_compatibility_56<br /><br />i.e. a variable that should be enabled by default and, as far as I understand, does not change the server behaviour (meaning the INFORMATION_SCHEMA will show the same info as in 5.6). Unfortunately I do not have a 5.7.X at hand to test it right now, but it looks like you should not have the problem you mentioned.<br /><br />That said, the funny part of the story is that the variable has been introduced in 5.7.6 _and_ deprecated in 5.7.6... weird.<br /><br />On top of it, I am not sure system variables are part of a performance schema, but as I said, I missed a lot of CPU cycles, so there must be a good reason for it.<br />The picky part of me would also argue that a variable with "show_" as a prefix that sets something, is pretty confusing.<br /><br /><br />Thanks again and hope to see you soon!<br />-ivan<br />Ivanhttps://www.blogger.com/profile/01969084252489590355noreply@blogger.com