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Displaying posts with tag: diagnostics (reset)
Today’s practical use-case for Performance Schema

Today’s blog post starts with a question:

“In my continuous integration environment, running tests currently takes 30 minutes. I
believe that a large percentage of time is spent in MySQL, and I want to know if putting MySQL
on tmpfs will cut that time down?”.

I have previously written about how to configure MySQL to be less durable in testing environments, but today I wanted to write about how we can really test the assumption that the question is based around. That is to say:

  • We know that total time is 30 minutes.
  • We assume MySQL is a large percentage of this.
  • We know that this optimization will potentially allow us to avoid IO.
  • We then want to know what amount of time MySQL spends waiting on IO during our test suite?

And the answer to …

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The MySQL error log in MySQL 5.7

The MySQL error log has received some attention in MySQL 5.7, with a new setting called log_error_verbosity.

There are three possible values, as documented in the manual:

Verbosity Value Message Types Logged
1 Errors only
2 Errors and warnings
3 Errors, warnings, and notes (default)

As Giuseppe has written about previously, writing notes or “informational events” can create debugging problems because they reduce the …

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