…accesses/index scans. For example retrieving index values first and then accessing rows in sorted order … which is completely disk bound can be very slow. One of the reasons elevating this problem …IO requests one by one for query execution, which means if single query execution time is your concern…
Post: Percona Toolkit Webinar followup Q&A
December 19, 2012 By 1 Comment
… it at the top, it’s just pt-query-digest master/data/telecaster-slow.log. As mentioned during the webinar, the tool… this way. Slide 38 is just the detail for the first query found. This is part of the same output from which…-query-digest –review S=/tmp/mysql_sandbox5527.sock,u=msandbox,p=msandbox,D=percona,t=reviews –report-all master/data/telecaster-slow…
Post: Optimizing slow web pages with mk-query-digest
April 7, 2011 By 14 Comments
… – I had a slow query log (captured with long_query_time=0 and all the eXtra benefits from Percona slow query log patch), I knew… mk-query-digest: mk-query-digest –filter=’$event->{Thread_id} == 160847′ in > out Now I know exactly what needs to be fixed first to make the greatest impact to this page response time. I can also convert that into a slow query log…
Post: Four ways to optimize paginated displays
September 24, 2008 By 27 Comments
… to log all queries) for one client; the slow log contains 6300 seconds’ worth of queries, and the two main queries for the paginated… results for my query.” Generally not — you usually look at the most helpful stuff, which is supposed to be first in the… paginated displays that can give significantly better performance. On the first query, fetch and cache all the results. Now it’s easy…
Post: Cache Miss Storm
September 10, 2010 By 30 Comments
… case of cache miss. To find first one for memcached you can use mk-query-digest to analyze which items are requested… a look at MySQL Slow queries – which is good enough if you populate each cache item with single query. Optimize query if you can… starting populating it. For MySQL Query Cache the solution should have been to make queries wait on first query started to complete. Unfortunately this…
Comment: Debugging sleeping connections with MySQL
May 20, 2009 By 30 Comments
… create a query wrapper function and open a connection to the database only when the first query occurs – e.g: function query ($query) { if (!mysql_connection) mysql_connect(); return mysql_query(); } – Reduce slow queries (always a good strategy…
Post: MySQL: Followup on UNION for query optimization, Query profiling
August 14, 2006 By 14 Comments
…. First I should mention double IN also works same way so you do not have to use the union. So changing query… me however show how you can profile queries to see what exactly happens during query execution – very helpful for MySQL Performance optimization… as BETWEEN range or as IN filesort appears and query becomes very slow: mysql> explain select * from people where age=18 order…
Post: Is it query which needs to be optimized ?
March 6, 2007 By 9 Comments
… is not query which needed to be optimized. Way too frequently people design schema first and then think how the queries they are… sort by another and then use LIMIT to output first few rows. This query is not going to be efficient as it…… if it is done using Index or it can be slow on large data sets if external filesort is used so…
Post: Solving INFORMATION_SCHEMA slowness
December 23, 2011 By 25 Comments
… and things like it. Besides being just slow accessing information_schema can often impact server performance…to refresh Innodb statistics each time table is queried from information schema. The solution is simple, … will still compute statistics for the table first time it opens it. Here are some …
Post: mk-query-digest, query comments and the query cache
… files as part of the query. This includes the general log, the binary log and the slow query log. Maatkit includes tools which… first space. A problem with this approach is that MySQL treats identical queries with different comments as different queries. This essentially renders the query…