… query in the right way. But vanilla MySQL does have its limitations, it reports only a subset of stats, however if you compare that….365434 Lock_time: 0.000000 Rows_sent: 1 Rows_examined: 655360 use test; SET timestamp=1325145746; select count(*) from auto_inc; Compare that… the longest sum of run time, query ranked #1. The first row in the table above shows the Count of number of times this query…
Post: Identifying the load with the help of pt-query-digest and Percona Server
December 29, 2011 By 3 Comments
Post: Shard-Query turbo charges Infobright community edition (ICE)
May 6, 2011 By 23 Comments
…only a small subset of the data, performance can be improved significantly: $ cat shards.ini [default] user=mysql…
Post: Distributed Set Processing with Shard-Query
May 14, 2011 By 27 Comments
…rows! Why would you break this paradigm by passing around rows instead of sets? From a distributed processing standpoint, rows…(or a mapped subset of nodes) the…of compute resource which speaks SQL, but right now only MySQL…_airport_id`), `count(*)`=`count(*)` + VALUES(`count(*)`), `sum(AirTime)`=`sum(…
Post: A case for MariaDB's Hash Joins
May 31, 2012 By Leave a Comment
…MySQL 5.5 is as follows: SELECT o.*, count…of rows in the table orders (left operand), and so MySQL 5.5 prefers to do a PRIMARY index scan of…t. First of all Hash joins only work…of the right-side table. However, Hash joins do not outperform BNL or BKA when you are joining a really small subset of rows…
Post: Tools and Techniques for Index Design Webinar Questions Followup
October 4, 2012 By 5 Comments
…of this book are still relevant to current versions of MySQL. Q: How do the upcoming changes in MySQL … theoretical cost of a query, by counting how many lookups to index entries or table rows will … a separate table, each index contains only values of its respective subset of the data. The index is …
Post: Goal driven performance optimization
December 22, 2008 By Leave a Comment
…of the problematic pages: mysql> select count(*),avg(wtime),avg(utime/wtime) cpu_ratio, avg(mysql_time/wtime) mysql… 1 row in set (2.29 sec) Why looking only at such pages is important ? This is because if you look at all pages rather than problematic subset…
