… answers: Q: Can you compare the use of subqueries/multiple joins vs. multiple queries (e.g. temp tables)? For performance, it’s… were using the tuple syntax to look up values against multiple columns in a compound index, then the order would matter… to count the movies per production year for each kind_id. It was more efficient in this case to force MySQL to…
Post: Is Synchronous Replication right for your app?
May 14, 2013 By 18 Comments
…MySQL replication from this instance, since MySQL replication is asynchronous. What about semi-sync MySQL … you can’t modify data on multiple cluster nodes simultaneously. You can. It… if( $last_count % 100 == 0 ) { $db->do( “UPDATE achievements SET count = $last_count where achievement = ‘killed_…
Post: Wow. My 6 year old MySQL Bug is finally fixed in MySQL 5.6
August 30, 2012 By 2 Comments
…at query execution: | Handler_read_next | 1305742982 | mysql> select count(*) from trunc where i=4147483647; +———-+ | count(*) | +———-+ | 0 | +———-+ 1 row in set, 1 … the bug in the real application which would use multiple table and the column type was inconsistent between them… …
Post: Shard-Query turbo charges Infobright community edition (ICE)
May 6, 2011 By 23 Comments
…queries against a MySQL database by distributing the work over multiple machines and/or multiple cores. This…in the table: mysql> select count(*), count(distinct UniqueCarrier) from dim_flightG *************************** 1. row *************************** count(*): 58625 count(distinct UniqueCarrier…
Post: Flexviews - part 3 - improving query performance using materialized views
April 4, 2011 By 20 Comments
…created by FlexCDC. The refresh algorithm computes changes in multiple transactions. After each transaction it must wait for …than COUNT(*). mysql> select count(*) cnt from order_lines\G *************************** 1. row *************************** cnt: 155187034 1 row in set (32.03 sec) mysql> …
Post: Why MySQL could be slow with large tables ?
June 9, 2006 By 141 Comments
… by index: mysql> select count(pad) from large; +————+ | count(pad) | +————+ | 31457280 | +————+ 1 row in set (4 min 58.63 sec) mysql> select count(pad) from… have whole bunch of problems solved just doing so. Use multiple servers to host portions of data set. Store portion of…
Post: How fast can MySQL Process Data
April 9, 2008 By 3 Comments
… mysql> select count(*) from m; +———-+ | count(*) | +———-+ | 1047684 | +———-+ 1 row in set (0.00 sec) mysql> select count(*) from m where i>0; +———-+ | count(*) | +———-+…(In reality I did multiple runs to get accurate results, but I show only one here) mysql> select sum(…
Post: Win Free MySQL Conference Tickets!
March 14, 2012 By 3 Comments
…us when we mention this contest Tweet “My favorite #MySQL conference session” with a link to your favorite “Like…sharing buttons on it. It is OK to enter multiple times — each time you enter increases your chances of… Just sign up for our newsletter and we’ll count that as an entry too.After a week, …
Post: MySQL: what read_buffer_size value is optimal ?
September 17, 2007 By 25 Comments
… and averaged results. MySQL 5.1.21-beta was used for tests. mysql> select count(*) from dt2 where slack like “a%”; +———-+ | count(*) | +———-+ | 4705992 | +———-+ 1…. It could be OS has to split large requests into multiple ones submitting them to device which slows things down or…
Post: Finding an optimal balance of I/O, CPU, and RAM for MySQL
May 16, 2011 By 4 Comments
… MySQL scales as you add more memory to the server. Vadim recently benchmarked the effects of increasing memory and CPU core count… storage — specifically, the Virident tachIOn drive — has more bandwidth than MySQL can fully utilize at present. Therefore, to decrease the price…. You can read the full details in our Scaling MySQL With Virident Flash Drives and Multiple Instances of Percona Server white paper.
