…to rebuild index by sort of key_cache as it can for MyISAM. EXPLAIN may take long time In MySQL…in select in from clause EXPLAIN might never complete. Solution is to run EXPLAIN for statements in FROM clause separately before looking at main query…reduces number of passes MySQL had to…
Post: Is MySQL 5.6 slower than MySQL 5.5?
February 18, 2013 By 23 Comments
…to remember about MySQL 5.6 is – it comes with Performance Schema enabled by default. Even though Performance Schema overhead was reduced in MySQL…time=300 run For single thread MySQL 5.5 is 11% faster than MySQL 5.6. If you disable Performance Schema in MySQL 5.6 comes to…
Post: Data compression in InnoDB for text and blob fields
May 30, 2012 By 2 Comments
…time to effect the table compression modification (given the long run-time…query request due to Barracuda not storing 768 bytes of the blob on field, and reduce the table down to…
Post: MySQL Query Cache
July 27, 2006 By 70 Comments
…to be cached. Query must be deterministic – Query might provide same result no matter how many times it is run…reduce query_cache appropriately. Otherwise you might wish to…to use query cache ? Third party application – You can’t change how it works with MySQL to add caching but you can enable query…
Post: Why you should ignore MySQL's key cache hit ratio
February 28, 2010 By 28 Comments
…to occur. How much of this query‘s execution time is consumed by those operations? Should I try to reduce Key_reads?” There is no way to…in MySQL to guide your decisions. It is also not the be-all and end-all of MySQL…
Post: MySQL 5.6 vs MySQL 5.5 and the Star Schema Benchmark
March 11, 2013 By 7 Comments
…to be moved to the hot portion. In MySQL 5.5 and earlier, innodb_old_blocks_time defaults to…in set (0.00 sec) After running the query, see how many pages were read from disk versus how many page requests their were: mysql…
Post: Optimizing slow web pages with mk-query-digest
April 7, 2011 By 14 Comments
… mysql connection is used during execution of a request. If you are seeking to reduce …time for some random user requests, you are usually interested in queries that are consuming most MySQL time and that’s how mk-query… all queries which is great, but I still need to figure out what queries were run….
Post: Slow Query Log analyzes tools
September 6, 2006 By 84 Comments
…time to execute combined. There is a tool mysqldumpslow in MySQL distribution which kind of does the thing – unfortunately being run on slow query…to see if only in certain cases query takes long time to execute, for example if plan is different based on constants. How to…
Post: Why do we care about MySQL Performance at High Concurrency?
February 26, 2013 By 9 Comments
…to MySQL server… this ends up with very high number of up to 10K connections and potentially running queries. Now imagine typically we have 30K queries…time and with a lot more user impact – after all slower responses will cause users to submit less requests to the system reducing…
Post: 10+ Ways to Crash or Overload MySQL
November 13, 2007 By 20 Comments
…MySQL server to run out of file descriptors. The same is true for Partitioned tables in MySQL…reduce system performance beyond being functional. General Overload As MySQL does not have much of resource utilization control you can simply run heavy queries to…
