Merging upstream version 1.44.3.

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 25 insertions, 0 deletions

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+### Understand the alert
+
+This alert presents the number of slow queries in the last 10 seconds. If you receive this, it indicates a high number of slow queries.
+
+The metric is raised in a warning state when the value is larger than 10. If the number of slow queries in the last 10 seconds exceeds 20, then the alert is raised in critical state.
+
+Queries are defined as "slow", if they have taken more than `long_query_time` seconds, a predefined variable. Also, the value is measured in real time, not CPU time.
+
+### Troubleshoot the alert
+
+- Determine which queries are the problem and try to optimise them
+
+To identify the slow queries, you can enable the slow-query log of MySQL:  
+
+1. Locate the `my.cnf` file 
+2. Enable the slow-query log by setting the `slow_query_log variable` to `On`.
+3. Enter a path where the log files should be stored in the `slow_query_log_file` variable.
+
+After you know which queries are the ones taking longer than preferred, you can use the `EXPLAIN` keyword to overview how many rows are accessed, what operations are being done etc.
+
+After you've found the cause for the slow queries, you can start optimizing your queries. Consider to use an index and think about how you can change the way you `JOIN` tables. Both of these methods aid to reduce the amount of data that is being accessed without it really being needed.
+
+### Useful resources
+[SQL Query Optimisation](https://opensource.com/article/17/5/speed-your-mysql-queries-300-times)
+