…MySQL Query Patterns, Optimized” for Percona MySQL…queries against the temp table fail. Q: Why doesn’t the query optimizer take care the execution…query that took half the time. An important conclusion of…
Post: More on MySQL transaction descriptors optimization
April 26, 2013 By Leave a Comment
… single SELECT queries doing PRIMARY KEY lookups (aka QPS sysbench mode); same MySQL queries executed inside …scalability is somewhere in between of MySQL 5.5 and MySQL 5.6. In order…count=8 –oltp-table-size=1000000 –rand-init=on –report-interval=1 –rand-type=uniform –forced-shutdown=1 –max-time…
Post: Flexviews - part 3 - improving query performance using materialized views
April 4, 2011 By 20 Comments
… cost (in terms of execution time) of the query on which the view is based. The SQL features used in the query on which the view… to calculate the number of lines in the order_lines table, three orders of magnitude more quickly than COUNT(*). mysql> select count(*) cnt from order…
Post: Identifying the load with the help of pt-query-digest and Percona Server
December 29, 2011 By 3 Comments
…of 167 different queries. Following that there are summaries of various data points such as the total query execution time and the average query execution time, the number of…of run time, query ranked #1. The first row in the table above shows the Count of number of times this query was executed…
Post: The four fundamental performance metrics
April 27, 2011 By 15 Comments
… metrics of activity on a system such as MySQL. In the…count the system’s “busy time” as the time during which at least one query…of queries in the interval. The total time during which queries resided in the system — the “busy time.” The total execution time of all queries — the “weighted time…
Post: Shard-Query turbo charges Infobright community edition (ICE)
May 6, 2011 By 23 Comments
…row *************************** count(*): 58625 count(distinct UniqueCarrier): 29 1 row in set (0.02 sec) Each year has tens of millions of flights: mysql> select count(*)… and response times were captured with the T command. The queries were executed on a single database schema containing all of the…
Post: Fun with the MySQL pager command
January 21, 2013 By 6 Comments
… timing information. This can be true if you are trying different execution plans for a query…querying INFORMATION_SCHEMA. For instance, counting the number of sleeping connections can be done with: mysql> SELECT COUNT(*) FROM INFORMATION_SCHEMA.PROCESSLIST WHERE COMMAND=’Sleep’; +———-+ | COUNT…
Post: Distributed Set Processing with Shard-Query
May 14, 2011 By 27 Comments
…of compute resource which speaks SQL, but right now only MySQL…Query can provide query execution plans based on the relational algebra rewrites So, here is an example of such a plan for a simple query…count(*)`=`count(*)` + VALUES(`count…
Post: How to convert MySQL's SHOW PROFILES into a real profile
February 20, 2012 By 12 Comments
SHOW PROFILES shows how much time MySQL spends in various phases of query execution, but it isn’t a full-featured profile. By that, … WHERE QUERY_ID = @query_id ), 2) AS Pct_R, COUNT(*) AS Calls, SUM(DURATION) / COUNT(*) AS “R/Call” FROM INFORMATION_SCHEMA.PROFILING WHERE QUERY_ID = @query…
Post: Be productive with the MySQL command line
December 21, 2012 By 14 Comments
…mysql client where you can type ; or \G to execute the query…count(*) from film; +———-+ | count(*) | +———-+ | 1000 | +———-+ 1 row in set (0.00 sec) mysql> exit And now if you look at the content of the queries…
