…get the following record in the slow query log: # Time: 120911 17:18:05 …returned up to the top level MySQL part for processing are counted the… produce group by results. What you can think about in this case is removing group by …or more this query is a very serious candidate for optimization. This is…
Post: MySQL Indexing Best Practices: Webinar Questions Followup
August 16, 2012 By 4 Comments
…and B between 100 and 200 order by B Very common for a date range to…slow down your inserts and make primary key significantly fragmented. I also would note there are some MySQL…mysql use index for group by? A: If you have Index on the column MySQL can avoid temporary table or filesort for group by by…
Post: MySQL 5.6 vs MySQL 5.5 and the Star Schema Benchmark
March 11, 2013 By 7 Comments
… slow (when the FS cache is cold, IO to slow IO…MySQL 5.6 server, rebooted and verified again. Same issue. This was very different from MySQL… like ‘%ssb%’ group by 1,2 ) sq order by pct_buffer_pool desc; +——————-+——————+——-+——+——+———+—————–+ …
Post: How Percona does a MySQL Performance Audit
November 24, 2008 By 17 Comments
…for giving me information about LVM devices, volume groups, and logical volumes. At this point, unless I…complete an action longer. If your application runs very short queries, this can be a non-… in total execution time. By the way, the slow query logs in the stock MySQL server are extremely limited,…
Post: MySQL: Followup on UNION for query optimization, Query profiling
August 14, 2006 By 14 Comments
… we want to show people in appropriate age group sorting by time when they were last online. …appears and query becomes very slow: mysql> explain select * from people where age=18 order by last_online desc limit 10; …
Post: Side load may massively impact your MySQL Performance
November 13, 2011 By 7 Comments
… be happening concurrently. It is very typical to hear complains about MySQL interactive performance – serving simple … mysqldump is running concurrently. mysqldump itself also slows down about 2x. What is going on here …p using(index_id) where t.schema=’test’ group by i.index_id \G INDEX_NAME DATA_…
Post: Advanced index analysis with mk-index-usage
November 11, 2010 By 2 Comments
… -p XXXX slow_query.log … have very different performance, …mysql> SELECT CONCAT_WS(‘.’, db, tbl, idx) AS idx, -> GROUP_CONCAT(alt_idx) AS alternatives, -> GROUP_CONCAT(DISTINCT query_id) AS queries, SUM(cnt) AS cnt -> FROM index_alternatives -> GROUP BY…
Post: DROP TABLE and stalls: Lazy Drop Table in Percona Server and the new fixes in MySQL
June 22, 2012 By 33 Comments
… rows, the tables all had a very simple structure: CREATE TABLE t_x(i…oltp-table-size=20000000 –mysql-table-engine=innodb –mysql-socket=/tmp/mysql_sandbox5524.sock –mysql-db=test –oltp-…slow log by setting long_query_time to 0. Then for analysis purposes the queries in the slow log were grouped by…
Post: Join Optimizations in MySQL 5.6 and MariaDB 5.5
April 4, 2012 By 4 Comments
… if you have a small buffer pool and a very large number of rows from table2 that do not…and l_shipdate > ’1995-03-09′ group by l_orderkey, o_orderdate, o_shippriority order by revenue desc, o_orderdate LIMIT 10;…that of MySQL 5.5. MariaDB 5.5 is quite slow as compared to both MySQL 5.5 and MySQL 5.6….
Post: New SpecJAppServer results at MySQL and Sun.
November 12, 2008 By Leave a Comment
…by MySQL…slow-queries=/tmp/mysql-slow.log long_query_time = 1 innodb_data_home_dir = /data/mysql/var innodb_data_file_path = ibdata1:10000M:autoextend innodb_file_per_table innodb_log_group_home_dir = /log/mysql…
