…then the movie immediately following the “gap” will be picked more frequently. Nearly every solution for randomly choosing rows…certain insert/update/delete operations. If you have a dataset that changes infrequently, then this … community at our events. The next one is in London on November 11-12…
Post: MySQL and the SSB - Part 2 - MyISAM vs InnoDB low concurrency
May 22, 2013 By Leave a Comment
… with a cold buffer pool. Then the query is tested again … and found that InnoDB does more IO than MyISAM when the … SSB Flight #4 There is one query in this flight, Q4….when a larger number of rows must be joined together (Q4.1…_stats_persistent innodb_stats_auto_update=off [mysqld_safe] log-error…
Post: More on MySQL transaction descriptors optimization
April 26, 2013 By Leave a Comment
…original tests we used a much larger one, 16 tables with 5M rows each (about 23GB). So it makes sense…HT as the culprit for the results difference. We then compared results across all 3 boxes to see …to scan about 100 update transactions to create a read view: I hope this sheds more light on our tests…
Post: Follow these basics when migrating to Percona XtraDB Cluster for MySQL
May 1, 2013 By 10 Comments
…. log_slave_updates is REQUIRED You need to have log_slave_updates enabled on … nodes, that is if you have more than one PXC node. This is because …good if your async master can use ROW based binlog format as well to achieve… tables without PRIMARY KEYs, then its time to make one for them. Galera does …
Comment: MySQL Partitioning - can save you or kill you
April 30, 2013 By 45 Comments
…one at a time. (Please provide specific references if you find otherwise.) I would argue that single-row queries (SELECT, INSERT, DELETE, UPDATE…one record. PARTITIONing makes very little difference. * If it cannot prune, then…efficient, much more efficient than DELETEing the equivalent rows. This is,…
Post: Recovering from a bad UPDATE statement
October 19, 2012 By 5 Comments
…one row changed — you don’t need anything fancy to recover from this failure case and can just run another UPDATE…UPDATE statement affected all rows in your very important big table? It might look more like this: UPDATE …As an exercise to the reader you would then need to: Stop database activity (set…
Post: Updated msl (microslow) patch, installation walk-through!
April 20, 2008 By 17 Comments
… there have been no updates to our msl patch, however recently… errors and message like this one: make[1]: Leaving directory `/home/… (see Configuration section for details). Then rename the binary, which can …row_limit rows to file. If you are not interested in queries which scan no more than N rows…
Post: MySQL-Memcached or NOSQL Tokyo Tyrant - part 1
October 15, 2009 By 16 Comments
… that reads two rows, and update one of them to read from memcached if available, remove on update, and read … they need to scale more, we need more memory! If performance sucks, we must need more. So here comes … result via that key. It then uses data from that random row to look up a second piece …
Post: Flexviews - part 3 - improving query performance using materialized views
April 4, 2011 By 20 Comments
… (that is, one which uses the incremental method) can be updated much more efficiently, by examining a history of the rows which have changed… an added benefit, if you build more than one complete refresh view from an incrementally refreshable one, then you can keep the complete views…
Post: High-Performance Click Analysis with MySQL
December 22, 2008 By 13 Comments
…Then write your queries to use the most aggregated data possible to save work. Avoid operations that update… impressions takes one row, and an ad that gets one impression takes exactly the same: one row. An… others, and there will continue to be more. Finally, PostgreSQL is clearly better for some…
