Percona's MySQL & InnoDB performance and scalability blog
I’ve heard this question a lot, but never thought to blog about the answer. “Is there a performance difference between putting the JOIN conditions in the ON clause or the WHERE clause in MySQL?” No, there’s no difference. The following queries are algebraically equivalent inside MySQL and will have the same execution plan.
1 2 3 4 5 | SELECT * FROM A, B WHERE A.ID = B.ID; SELECT * FROM A JOIN B ON A.ID = B.ID; SELECT * FROM A JOIN B USING(ID); |
Personally, [...]
…any sessions this year; Peter, Vadim, and the rest of us at Percona submitted over a dozen session proposals, which were initially declined. As …Cabral is organizing.
That’s the back story — now on to the Percona Performance Conference! This is not “another MySQL conference.” It’s a performance…to Santa Clara.
We will not be the only ones speaking at Percona Performance Conference; other experts will join us in making presentations too. …to propose a session, please do so through the Percona Performance Conference website.
The Percona team looks forward to greeting you face to face …
One of my favorite MySQL configurations for high availability is master-master replication, which is just like normal master-slave replication except that you can fail over in both directions. Aside from MySQL Cluster, which is more special-purpose, this is probably the best general-purpose way to get fast failover and a bunch of other benefits (non-blocking ALTER [...]
Vadim wrote some time ago about how to find unused indexes with single query. I was working on the system today and found hundreds of unused indexes on dozens of tables so just dropping indexes manually did not look fun. So I extended Vadim’s query to generate ALTER TABLE statements automatically. I also made it [...]
July 31st 2006 was my last day working for MySQL and August 1st I started what later was incorporated Percona with Vadim joining me September 1st as co-founder. Two years is a significant anniversary for any startup – surviving (and being profitable) for 2 years can be seen as validation of our business model and [...]
Its almost a month since I promised Heikki Tuuri to answer Innodb Questions. Heikki is a busy man so I got answers to only some of the questions but as people still poking me about this I decided to publish the answers I have so far. Plus we may get some interesting follow up questions [...]
I start to see applications being built utilizing VIEWs functionality which appeared in MySQL 5.0 and quite frequently VIEWs are used to help in writing the queries – to keep queries simple without really thinking how it affects server performance. Even worse than that – looking at the short table which just gets single row [...]
I prefer to use Integers for joins whenever possible and today I worked with client which used character keys, in my opinion without a big need. I told them this is suboptimal but was challenged with rightful question about the difference. I did not know so I decided to benchmark. The results below are for [...]
In many Search/Browse applications you would see main (fact) table which contains search fields and dimension tables which contain more information about facts and which need to be joined to get query result. If you’re executing count(*) queries for such result sets MySQL will perform the join even if you use LEFT JOIN so it [...]
About half a year have passed since me and Vadim have left MySQL to do MySQL Consulting on our own. Bunch of people have been wondering about our experiences so I thought it would be worth to share it here.
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