… fetched, and N is the buffer size. In MySQL 5.6 the buffer size used by MRR can be controlled by the variable… in MariaDB 5.5 and not in MySQL 5.6, is that because of a bug in MySQL 5.6 code? As MRR was used in both MySQL 5.6 and MariaDB 5.5. Handler_mrr_rowid_refills counts how…
Post: Troubleshooting MySQL Memory Usage
March 21, 2012 By 3 Comments
…in most cases you do not know where exactly memory is allocated. This was not much of the problem in MySQL…uses MySQL to identify potential causes. Is it working with large blobs ? Using user variables ? Prepared Statements ? memory tables ? In… to look at Prepared_stmt_count to see how many prepared …
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… limitations in cases such as range scans, where index parts after the part on which range condition is applied cannot be used…
Post: Win Free MySQL Conference Tickets!
March 14, 2012 By 2 Comments
… you should not miss if you’re at all interested in MySQL. We really want you to be there — and that’s…,” or +1 a session, just browse to the session and use the social sharing buttons on it. It is OK to… win! Just sign up for our newsletter and we’ll count that as an entry too.After a week, we’ll…
Post: How FLUSH TABLES WITH READ LOCK works with Innodb Tables
March 23, 2012 By 20 Comments
… | 10219 | root | localhost | dumptest | Query | 324 | Sending data | select count(*) from A,B | 0 | 0 | 2359297 | | 10290 | root | localhost | NULL… tools used by mysql client, so you might get a feel you can’t connect to the database at all (use mysql -A in this…
Post: Best kept MySQLDump Secret
March 23, 2012 By 11 Comments
…mysql> show tables; +——————–+ | Tables_in_dumptest | +——————–+ | A | | B | | C | +——————–+ 3 rows in set (0.00 sec) mysql> select count(*) from A; +———-+ | count(*) | +———-+ | 2359296 | +———-+ 1 row in…. You can also use Percona Xtrabackup, LVM…
Comment: ext4 vs xfs on SSD
April 24, 2012 By 23 Comments
…the bug list or patch list for MySQL/InnoDB at any one point in time. The list will be long… unless something is completely broken. There used to be, and in some places still is a developer culture …check. So in the first count, you are reacting to a patch issue in a way that is “fussy” in the extreme…
Comment: Percona XtraDB Cluster Feature 2: Multi-Master replication
April 2, 2012 By 16 Comments
Etian what have you compared? Using Galera one approach is to compare with semisync replication. Even … it is written in german but the graphs count. You see galera faster than MySQL 5.5.21 semisync (blue line). MySQL was getting…. Galere performs awesome and you don’t have the data in the relay log only. And don’t forgett you can…
Post: Flexviews - part 3 - improving query performance using materialized views
April 4, 2011 By 12 Comments
…. The incremental method is somewhat conceptually similar to using mysql binary logs for point-in-time recovery after a restoring a backup. Since… use this summary to calculate the number of lines in the order_lines table, three orders of magnitude more quickly than COUNT(*). mysql> select count… 484 less lines reflected in the count in our MVs but they are out-of-date and must be refreshed: mysql> select sum(total…
Post: Percona Replication Manager, a solution for MySQL high availability with replication using Pacemaker
November 29, 2011 By 94 Comments
… we started looking at other ways of achieving higher availability using MySQL replication. One of the weakness of MMM is its communication… Ubuntu Lucid VM, this file goes in /usr/lib/ocf/resource.d/heartbeat/ directory. To use this agent, you’ll need a… and test_passwd: The credentials to test MySQL. Default is to run select count(*) on mysql.user table, so the user given should…
