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Displaying posts with tag: down (reset)
Working Around MySQL Cluster Push Down Limitations Using Subqueries

I worked on an issue last recently where a query was too slow when executed in MySQL Cluster. The issue was that Cluster has some restrictions when it comes to push down conditions.

As an example of this, consider the following query using the employees sample database. The query takes a look at the average salary based on how many years the employee has been with the company. As the latest hire date in the database is in January 2000, the query uses 1 February 2000 as the reference date.

Initially the query performs like (performance is with two data nodes and all nodes in the same virtual machine on a laptop, so the timings are not necessarily representative of a production system, though the improvements should be repeatable):

mysql> SELECT FLOOR(DATEDIFF('2000-02-01', hire_date)/365) AS LengthOfService,
              COUNT(DISTINCT employees.emp_no) AS NoEmployees, AVG(salary) AS AvgSalary
         FROM salaries …
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The Website is Down: Sales Guy vs. Web Dude

This video has been going around for some time now, but I think its worth the post for those that have yet to see it.

Video Source: The Web Site is Down

Showing entries 1 to 2