… see with people using EXPLAIN is trusting it too much, ie assuming if number of rows is reported by EXPLAIN is large query… queries if you have any hesitations in EXPLAIN accuracy. The other problem however is EXPLAIN does not take LIMIT into account while…. Too bad –min-examined-row-limit is not yet implemented 
EXPLAIN would also return misleading number of rows for queries of…
Post: When EXPLAIN can be misleading
November 12, 2006 By 1 Comment
Post: How Percona does a MySQL Performance Audit
November 24, 2008 By 17 Comments
…’re getting good service. A Percona consultant never says “just trust me” unless the client really insists “I don’t want… need to really know how to write queries and how EXPLAIN works. At Percona, we have peer training constantly on our… (execution times, etc), the EXPLAIN plan, and the desired modifications to the query or the table. We explain how to interpret what…
Post: Why you should ignore MySQL's key cache hit ratio
February 28, 2010 By 27 Comments
…, what use would the key buffer be anyway? Let’s trust MyISAM’s creators on this one, because they designed a… and in fact, ignore Key_read_requests altogether. I’ve explained that counters are a surrogate measure, but the fact that… happens. In the absence of timing information, and if you trust the cache’s creator and assume that misses are more…
Post: Beware the Innodb Table Monitor
November 29, 2011 By 2 Comments
… was writing an email to the customer to explain it, I got an email explaining that he saw a big spike in…/dict0dict.c: line 4883 So, the io-wait spike is explained by table statistics being regenerated, and the SHOW PROCESSLIST connections…. Just because it’s old, doesn’t mean you should trust it.
Comment: Percona Server vs MySQL on Intel 320 SSD
February 23, 2012 By 21 Comments
I trust Vadim’s benchmarks because he either shows what’s happening in the system and explains it, or he shows what’s happening and says more investigation is needed. I can’t tell if Axel knows more and didn’t present the results, or whether he’s satisfied not knowing how to explain his results.
Comment: Percona Replication Manager, a solution for MySQL high availability with replication using Pacemaker
December 1, 2011 By 94 Comments
… that there would be an agent that I would actually trust to do all the correct steps in a failover situation… couldn’t do what MHA does). But the design you explained in London does sound correct, so what Yves publishes here…
Post: The two even more fundamental performance metrics
May 5, 2011 By 6 Comments
…,” I am about out of descriptive words. The metrics I explained in the last post were all about observing events and… the following plot: That’s getting pretty crowded, but just trust me when I say that you can zoom into it…
Post: MySQL Binaries availability
January 19, 2007 By 9 Comments
… people are just speaking about binaries in general. As Kaj explains now there will be official MySQL Community binaries, including Windows… Windows. I guess over next few months community will establish trusted sources of MySQL Builds and you will be able to…
