… on the columns of table t1 that are two be used to join rows with table t2. This step is called the… is quite slow as compared to both MySQL 5.5 and MySQL 5.6. For MariaDB 5.5 the query time decreases when the… that the query on MariaDB 5.5 is slow as compared to MySQL 5.6. Next interesting thing are the last two columns of…
Post: Multi Range Read (MRR) in MySQL 5.6 and MariaDB 5.5
March 21, 2012 By 10 Comments
…. Note also that query time for MariaDB is still a little higher by a couple of seconds, when compared to MySQL 5.6… Handler_read_key and Innodb_rows_read to be incremented by TWO. It does not actually mean that queries with MRR are performing… extra sorting overhead which means that the queries are just a bit slower as compared to MySQL 5.5 MRR clearly changes the…
Post: Index Condition Pushdown in MySQL 5.6 and MariaDB 5.5 and its performance impact
March 12, 2012 By 12 Comments
… working with Peter in preparation for the talk comparing the optimizer enhancements in MySQL 5.6 and MariaDB 5.5. We are… optimizer enhancement Index Condition Pushdown (ICP). Its available in both MySQL 5.6 and MariaDB 5.5 Now let’s take…
Post: Using Flexviews - part two, change data capture
March 25, 2011 By 11 Comments
… summarize data. Using the aggregated data can significantly improve query response times compared to accessing the non-aggregated data. Keeping MVs up…. Insert data in one transaction (two rows): mysql> insert into test.demo values (NULL,2),(NULL,3); Query OK, 2 rows affected (0.00 sec…
Post: Identifying the load with the help of pt-query-digest and Percona Server
December 29, 2011 By 3 Comments
…query in the right way. But vanilla MySQL does have its limitations, it reports only a subset of stats, however if you compare…Query_time: 0.117904 Lock_time: 0.002886 Rows_sent: 1 Rows_examined: 655360 Rows_affected: 0 Rows…_blog_two (34/22%)… 1 more # Query_time distribution # 1us # 10us # 100us …
Post: Shard-Query EC2 images available
May 11, 2011 By 2 Comments
…mysql> show table status like ‘ontime_fact’G *************************** 1. row *************************** Name: ontime_fact Engine: InnoDB Version: 10 Row_format: Compact Rows: 6697533 Avg_row…compared to Innodb, 8:1 compared…
Post: Flexviews - part 3 - improving query performance using materialized views
April 4, 2011 By 12 Comments
…now is that there are two significant differences between the methods… Refreshed both views. Compared the refresh performance and query results. The view…Query OK, 0 rows affected (42 min 42.14 sec) mysql> call flexviews.enable( -> flexviews.get_id(‘demo’,'dashboard_customer_sales’)); Query OK, 0 rows…
Post: A micro-benchmark of stored routines in MySQL
August 16, 2009 By 7 Comments
…query is doing a table scan against the first query, and then executing the subquery for each row: mysql> explain select ….\G *************************** 1. row…, but the further two rows are not shown. The query can’t be optimized… first query! (If you think of a better way to compare apples and …
Post: What do we optimize with mk-query-digest ?
December 15, 2009 By 2 Comments
…row level locks, table locks all could cause query response time to be unreasonable. If Slowest query is not interactive query…MySQL user compared to the web site itself as it makes it easier to remove such queries from analyzes. What is Important to mention neither of these two query …
Post: MySQL 6.0 vs 5.1 in TPC-H queries
March 25, 2008 By 17 Comments
… with queries from TPC-H benchmarks, particularly comparing MySQL 6.0.4-alpha with 5.1. MySQL 6….should affect execution plan of TPC-H queries. In reality only two queries (from 22) have significantly better … we had during execution of query, as MySQL used index to scan rows and then did access…
