… your 9x percentile response time performance until you use it against your work load with your dataset with your queries; thats what… benefit immediately in terms of those incremental schema changes or query changes instead of a tool to gage scaling limitations of… have a sharded datastore. A possible solution is to use mysql proxy and an alterate server with a snapshotted dataset and…
Post: Identifying the load with the help of pt-query-digest and Percona Server
December 29, 2011 By 3 Comments
… points you need to attack the right query in the right way. But vanilla MySQL does have its limitations, it reports only…% (95th percentile) column as that gives us more accurate understanding. Now, for example it is shown here that every query is reading… the queries that you can use to gather more data about the underlying tables involved and the query execution plan used by MySQL…
Post: What do we optimize with mk-query-digest ?
December 15, 2009 By 2 Comments
… acceptable for interactive queries. It is best to look at 95 percentile “time” rather than slowest time for the queries as there are… jobs use different MySQL user compared to the web site itself as it makes it easier to remove such queries from analyzes… to get bad performance with MySQL responsible for large portion of response time without any slow queries. We’ve seen pages which…
Post: Computing 95 percentile in MySQL
November 28, 2008 By 5 Comments
… 99 percentile is much better. Say you say 99 percentile response time should be one second, this means only 1 percent of queries…/99 percentile and get your logs in the table, so how to get the data if MySQL only provides you the avg: mysql… time we concerned about simply by running following order-by queries: mysql> select wtime from performance_log_081128 where page_type=’search…
Post: mysql-proxy, urgh performance and scalability ?
June 9, 2009 By 27 Comments
… thread). MySQL per-request statistics: min: 1.31ms avg: 1.51ms max: 5.30ms approx. 95 percentile: 1.56ms Proxy+MySQL per-request statistics: min: 2.04ms avg: 2.86ms max: 6.44ms approx. 95 percentile: 4…. Worth to consider if you want to run Query Analyzer with MySQL-proxy on your MySQL Enterprise setup. There is alternative – Dormando-proxy…
Post: The two even more fundamental performance metrics
May 5, 2011 By 6 Comments
… calculate the standard deviation, the median, any desired percentile (depending on how large your sample is), the … maybe a bit longer. This is common in MySQL servers I work with when they’re …spike. We could also classify queries together and analyze the classes of queries, rather than lumping all …
Post: Introducing tcprstat, a TCP response time tool
August 31, 2010 By 12 Comments
… many simple protocols such as HTTP and MySQL, this is the moral equivalent of a query‘s response time. The statistics we…, in microseconds. These are repeated for the 95th and 99th percentiles as well. Other metrics are also available. Here’s a…
Post: Color code your performance numbers
June 2, 2010 By 4 Comments
…. We most likely would like to see some percentile numbers – 95 percentile or 99 percentile. The problem is computing these in SQL is… 3 seconds and anything over that will be considered unacceptable: mysql> select sum(wtime=1.0 and wtime=3.)/count(*)*100… before we get large number of yellow or red requests: mysql> select avg(if(wtime
Post: Tuning InnoDB Concurrency Tickets
May 24, 2010 By 4 Comments
… stock install of MySQL, here are some example queries and the corresponding number of concurrency tickets used for each: mysql> CREATE TABLE test…: 0 Warnings: 0 mysql> DELETE FROM child WHERE 1; — 6 Tickets Used Query OK, 3 rows affected (0.02 sec) mysql> ALTER TABLE… scenario, you will tune innodb_concurrency_tickets to the 99th percentile of small PK lookups. If you’re optimizing for response…
Post: Goal driven performance optimization
December 22, 2008 By Leave a Comment
… also we speak about percentile response time rather than “all queries“. It is surely good all search queries complete in one seconds but… of the stack. If you look at MySQL log you may find some queries which are slow but it is hard to… for complex applications using mutliple components (like sphinx and MySQL) or multiple MySQL Servers because in these cases you often can’t…
