June 19, 2013

Post: Multi Range Read (MRR) in MySQL 5.6 and MariaDB 5.5

… Now let’s move on to the benchmarks, to see the difference….89G 1.53G Innodb_data_reads 120552 123872 100551 … scans had to be performed. As in the table above you …to MySQL 5.5 MRR clearly changes the access pattern to sequential, and hence InnoDB is able to do many read_aheads. Another thing to

Post: How much overhead is caused by on disk temporary tables

data to be read from the disk as nothing was written. So I filled bug on this. So what was performance mysqltables are moderately sized). Unfortunately I ran into another bug which means I will have to postpone this part of test to another

Post: The story of one MySQL Upgrade

…so we just have to keep this into account. We move database to MySQL 5.1 As …used mk-table-checksum to ensure the data is in sync. mk-table-checksum can use replication to check…Another table remained though. We used mk-table-sync –print as a diff tool for MySQL to see what is different in the tables

Post: Recovering CREATE TABLE statement from .frm file

…InnoDB data files but have forgotten to delete the corresponding .frm files of InnoDB tables, or you have moved .frm files to another database? or, the table contains indexes that this version of the engine doesn’t support. See http://dev.mysql

Post: Heikki Tuuri answers to Innodb questions, Part II

… the OS version. In our tests, removing one bottleneck moves the contention to another place. Thus, no general rules can be established. I… large data manageable. MySQL Master Master Manager can help you to automate it a bit. I also like to keep tables small enough, “sharding” to many tables

Post: MySQL Crash Recovery

to crash again – such crashes qucikly following one another are kind of worse because they explore many less tested code paths in MySQLmoves out all MyISAM tables out of MySQL database directory, checks them with MyISAMchk and moves them back to… Full table scan queries allow to preload table data

Post: Index Condition Pushdown in MySQL 5.6 and MariaDB 5.5 and its performance impact

… in preparation for the talk comparing the optimizer enhancements in MySQL 5.6 and MariaDB 5.5. We are taking a… optimizer enhancement Index Condition Pushdown (ICP). Its available in both MySQL 5.6 and MariaDB 5.5 Now let’s take…

Post: Helgrinding MySQL with InnoDB for Synchronisation Errors, Fun and Profit

to think of any harm that may happen here due to the way this variable is used. Moving on. ==9090== Possible datatable_state) (sql_show.cc:6238) ==9090==    by 0x6A5E0C: JOIN::exec() (sql_select.cc:1863) ==9090==    by 0x6A7D72: mysql_select(THD*, Item***, TABLE…it by finding another (related) lock …

Post: InnoDB Full-text Search in MySQL 5.6 (part 1)

… whom the prudent move would be a migration to InnoDB, but due to their use of MyISAM FTS, the idea of a complete or partial migration was, for one reason or anotherdata into the table, run an OPTIMIZE or two, delete some data, and see what happens: mysql> set global innodb_ft_aux_table

Post: Estimating Replication Capacity

to schedule downtime or set object read only to move it to anothermysql> select * from information_schema.user_statistics where user=”#mysql_system#” \G *************************** 1. row *************************** USER: #mysql