… transaction optimization in MySQL 5.6, because all SELECT queries in the AUTOCOMMIT mode… So it makes sense to check if the dataset size makes any …mysql-user=root –mysql-db=sbtest8t1M –mysql-table-engine=INNODB –mysql-socket=/tmp/mysql.sock –oltp-point-selects=1 –oltp-simple-ranges=0 –oltp-sum…
Post: Percona XtraDB Cluster 5.5.30-23.7.4 for MySQL now available
April 17, 2013 By 2 Comments
… option in the wsrep_provider_options variable. Accepted values are in the range [0, 255] (inclusive). Quorum is computed using weighted sum over… and leave a slave hanging. Bug fixed #1130888 (Seppo Jaakola). If MySQL replication threads were started before running wsrep recovery, this would… Snapshot Transfer with Xtrabackup would fail if the tmpdir was specified more than once in the MySQL configuration file (my.cnf). Bugs fixed…
Post: Benchmarking Percona Server TokuDB vs InnoDB
May 7, 2013 By 32 Comments
…$I_r1000, with roll-up sum for 10, 100, 1000 records in the main table. and transactions … will interesting how both InnoDB and TokuDB performs if PK is (`id`,`hid`,`mid`). This also …myisam_repair_threads = 1 myisam_recover socket=/var/lib/mysql/mysql.sock user=root skip-grant-tables TokuDB-related…
Post: How to Identify Bad Queries in MySQL
January 10, 2011 By 16 Comments
… system by grouping queries into classes and summing the execution time together. Then it prints … is best done by observing clusters in query end times. If there is a sudden burst of queries…been available in MySQL for years. This is necessary for determining whether a group of queries completed in a…
Post: Troubleshooting MySQL Memory Usage
March 21, 2012 By 5 Comments
… so in most cases you do not know where exactly memory is allocated. This was not much of the problem in MySQL 3… going away if you close connection. In Percona Server you can do better as you can query temporary tables too: mysql> select sum(data… memory leaks and I would say these are rather rare in MySQL. Most suspected memory leaks end up being some run away…
Post: A micro-benchmark of stored routines in MySQL
August 16, 2009 By 7 Comments
… execution plan. You should never use IN() subqueries the way I do, at least not in MySQL 5.1 and earlier. I loaded the World sample database and cooked up this query: select sql_no_cache sum… is why I purposefully wrote the subquery badly in the first query! (If you think of a better way to compare apples…
Post: Join Optimizations in MySQL 5.6 and MariaDB 5.5
April 4, 2012 By 4 Comments
… This means many point queries, say for example if table1 yields 1000 rows then 1000 index lookups…in both MySQL 5.6 and MariaDB 5.5. You can read more about BKA in MySQL 5.6 here and BKA in…in case of MariaDB 5.5. You can read more about these variables here. The query used is: select l_orderkey, sum…
Post: Multi Range Read (MRR) in MySQL 5.6 and MariaDB 5.5
March 21, 2012 By 10 Comments
…. The query used is: select c_custkey, c_name, sum(l_extendedprice * (1 – l_discount)) as revenue, c_acctbal,… not in MySQL 5.6, is that because of a bug in MySQL 5.6 code? As MRR was used in both MySQL 5… small and not all index tuples could fit in the buffer. If this is > 0 then it means Handler_mrr…
Post: Index Condition Pushdown in MySQL 5.6 and MariaDB 5.5 and its performance impact
March 12, 2012 By 12 Comments
I have been working with Peter in preparation for the talk comparing the optimizer enhancements in MySQL 5.6 and MariaDB 5.5. We are taking a look at and benchmarking optimizer enhancements one by one. So in… new optimizer enhancement Index Condition Pushdown (ICP). Its available in both MySQL 5.6 and MariaDB 5.5 Now let’s take…
Post: MySQL 5.6 vs MySQL 5.5 and the Star Schema Benchmark
March 11, 2013 By 7 Comments
… able to move to the hot list. In MySQL 5.6 the default value of innodb_… from joining the tables in the other direction mysql> select straight_join sum(lo_extendedprice*lo_discount) …tinyint, D_WeekDayFl tinyint ); DROP TABLE IF EXISTS lineorder; CREATE TABLE IF NOT EXISTS lineorder ( LO_OrderKey …
