June 19, 2013

Post: Shard-Query EC2 images available

May 11, 2011 By 2 Comments

…of input data on my i970 test machine. It is possible to distribute splitting and/or loading among multiple… to 2010′; mysql> use ontime1; Database changed mysql> show table status like…_query command, called pivot_results cd shard-query/ $ ./run_query < queries.sql | tee raw |./pivot_results & [1] …

Filed Under: MySQL

Post: How Much memory do you use to run MySQL

November 2, 2012 By 8 Comments

… number of issues with MySQL Server related to amount of memory you have in the system – these range from problems with large size Query… use to run MySQL Server these days ? [poll id="2"] Feel free to select multiple sizes if you have multiple kinds of instances in… pool open until the end of the year when it will be frozen so we do not get results from multiple years mixed.

Filed Under: Insight for DBAs, MySQL, Polls

Post: The perils of uniform hardware and RAID auto-learn cycles

November 16, 2010 By 16 Comments

… over a short time span (a couple of hours). Queries were taking multiple seconds to execute instead of being practically instantaneous. But nothing seemed… quickly on one of the failing machines. The result: the battery-backed cache was in write-through mode instead of write-back mode…

Filed Under: Hardware and Storage, MySQL Tagged With: , , , ,

Post: MySQL Query Cache

July 27, 2006 By 70 Comments

… Oracle Query Cache – meaning cache where execution plans are cached. MySQL Query Cache is not. It does not cache the plan but full result… all queries derived from this table are invalidated at once. Most of them quite likely would not have change their result set but MySQL… slaves and use query cache on all of them cache content will likely be the same, so you have multiple copies of the same…

Filed Under: Insight for DBAs Tagged With:

Post: Multiple column index vs multiple indexes

August 22, 2008 By 13 Comments

… them multiple times and measured time appropriately. To remove the overhead of starting MySQL etc from equation I also measured execution of “SELECT 1″ query… result in the table. time for ((i=0;i /dev/null In the result table I compute per query results and present results in milliseconds. Query…

Filed Under: Benchmarks, Insight for DBAs

Post: The Optimization That (Often) Isn't: Index Merge Intersection

December 14, 2012 By 6 Comments

… types of queries which contain WHERE clauses with columns that had single-column indexes on them, MySQL could sometimes make use of the multiple indexes… union of the two result sets. Replace that “OR” with an “AND” and you might see the set-theoretic intersection of the result sets…

Filed Under: Insight for DBAs, Insight for Developers, MySQL

Post: PHP Large result sets and summary tables.

July 6, 2007 By 8 Comments

…of Ram (and plenty of swap space) like crazy. Why ? Because by default mysql_query uses mysql_store_result C library call and buffers all result…MySQL result set. OK there is “easy” fix for this problem, you can use mysql_unbuffered_query… data flushes, ie with multiple value INSERTs etc. This …

Filed Under: Insight for Developers Tagged With: ,

Post: Fighting MySQL Replication Lag

September 22, 2008 By 7 Comments

…couple of query design mistakes which result in low hanging fruit troubleshooting MySQL Replication Lag First fact you absolutely need to remember is MySQL …amount of values per batch in multiple row insert statement or Fetching data you’re planning to update/delete and having multiple queries to…

Filed Under: Insight for DBAs Tagged With: ,

Post: InnoDB Full-text Search in MySQL 5.6: Part 2, The Queries!

March 4, 2013 By 7 Comments

… run some queries and compare the result sets. Our hope is that the one of two things will happen; either the results returned from… we change the above query to be “+james +peterson arizona” then we might expect to get back multiple matches containing the words… involved. Always test how your application behaves as a result of a major MySQL version upgrade before rolling it into production! Percona has…

Filed Under: Insight for DBAs, Insight for Developers, MySQL Tagged With: , , , , ,

Post: Talking MySQL to Sphinx

April 19, 2009 By 4 Comments

…of other queries, not using Full Text Search. [root@r27 sp]# mysql –host 127.0.0.1 –port 3307 Welcome to the MySQL…multiple CPU cores and multiple nodes in the system. The raw scan speed was almost 10 millions of…

Filed Under: Insight for Developers Tagged With:
« Older Posts
Newer Posts »