June 17, 2013

Comment: MySQL Partitioning - can save you or kill you

MySQL. PARTITIONs are scanned one at a time. (Please provide specific references if you find otherwise.) I would argue that single-row queries (SELECT, INSERT, DELETE, UPDATE) are similar in speed between…partitions. * A ‘range’ delete would mostly follow above two points. * Secondary…

Comment: MySQL Partitioning - can save you or kill you

… reads across the DB (most appearing in one section …Mysql can fire off one thread per partition (at least I have seen this happen in a MyIsam environment on similar sized tables). What I am really saying is that its not only about the ‘Selects…few hundred thousand rows… for example, if you…

Post: How to convert MySQL's SHOW PROFILES into a real profile

… that, I mean that it doesn’t show similar phases aggregated together, doesn’t sort them …demonstrate: mysql> SET profiling=1; mysql> pager cat > /dev/null mysql> SELECT * FROM nicer_but_slower_film_list; 997 rows in… 35 rows in set (0.00 sec) It’s pretty hard to figure out what consumed the most time…

Post: Shard-Query turbo charges Infobright community edition (ICE)

MySQL database by distributing the work over multiple machines and/or multiple cores. This is similarmysql> select count(*), count(distinct UniqueCarrier) from dim_flightG *************************** 1. row *************************** count(*): 58625 count(distinct UniqueCarrier): 29 1 row

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

…; I would argue that in most situations, any possible advantages to …search), that’s largely where the similarities end. NOTE 1: I was …optimize | status | OK | +———————-+———-+———-+———-+ 1 row in set (4.60 sec) mysql> select * from information_schema.innodb_ft_config; …

Post: High-Performance Click Analysis with MySQL

… advertising, user behavior analysis, and many similar types of work.  The …it on the master with INSERT..SELECT queries, it will propagate to … that read a lot of rowsMySQL can’t handle too many of…MySQL is, especially for more complex queries. Percona is not tied to MySQL, although we’re most

Post: Percona XtraDB Cluster: Multi-node writing and Unexpected deadlocks

row affected (0.01 sec) Rows matched: 1 Changed: 1 Warnings: 0 node3 mysql> commit; Query OK, 0 rows affected (0.00 sec) node3 mysql> select…up with an HAproxy configuration or similar so if your main writer node… perfectly natural, but I believe most conventional relational databases will naturally …

Post: SELECT LOCK IN SHARE MODE and FOR UPDATE

mysql> commit; Query OK, 0 rows affected (0.01 sec) SESSION2: mysql> select * from tst; Empty set (0.00 sec) mysql> selectrow. Think about similar case and row being deleted. Even if Innodb would be able to set locks on rows… and make sure we’re reading most current data, plus to ensure it …

Post: Using any general purpose computer as a special purpose SIMD computer

… on the surface appears to be similar to other technologies on the market today… does this work? Here is the most important part of the explain plan… mysql> select min(id),max(id) from words; +———+———+ | min(id) | max(id) | +———+———+ | 1 | 3088896 | +———+———+ 1 row