… smallest data types you can, the simplest character sets you can, and watch out for NULLable columns….database in a little meta-table. Then your script can figure out which files it can ignore…. your application in advance. What about partitioning in MySQL 5.1? I know there are some cases when it…
Post: Edge-case behavior of INSERT...ODKU
October 27, 2012 By 6 Comments
…in which they were defined, and the PRIMARY KEY is always going to be considered as being defined first. So, MySQL… | 10 | NULL | +————+———-+———+———————+ 2 rows in set (0.00 sec) …’t the case. (root@localhost) [test]> select * from update… and purposes, ignored. For …
Post: Flexviews - part 3 - improving query performance using materialized views
April 4, 2011 By 20 Comments
…In cases where this is not useful, simply ignore this column. It is used to prevent wide innodb primary keys on the MV. mysql…
Post: The story of one MySQL Upgrade
October 8, 2010 By 8 Comments
…MySQL to see what is different in the tables. It turned out one of the float columns stored “-0″ in MySQL… the issue for application and could be ignored. So at this point we were …sets. –compare-results-method rows helped to remove them and we were down to only query time differences. In most cases…
Post: MySQL 5.6 Compatible Percona XtraBackup 2.0.6 Released
March 20, 2013 By 2 Comments
…a large increase in disk usage in cases when there are… subdirectories to be ignored by XtraBackup without warning…in innobackupex or the –tables option in xtrabackup. Bug fixed #1130627 (Alexey Kopytov). innobackupex didn’t add the file-per-table setting…6 for MySQL 5.6 are available in our online…
Post: A rule of thumb for choosing column order in indexes
June 5, 2009 By 15 Comments
… to decide which columns should come first in an index. This is not specific to MySQL, it’s generally applicable to any… there are a bunch of subtleties, but I will also ignore those for the sake of simplicity. Let’s start with…
Post: MongoDB Approach to database synchronization
April 30, 2010 By 5 Comments
… data on the new Master. In MySQL world we can chose to either ignore this problem (or may be … expensive for large databases. MongoDB approach used in Replication Sets is for failed master to scan its log… and they can be dumped to local file (in case one wants to synchronize them manually) and when …
Post: Percona XtraDB Cluster: Failure Scenarios with only 2 nodes
July 25, 2012 By 6 Comments
…in this case. – pc.ignore_sb : Should we allow nodes to process updates even in the case of split brain? This is a dangerous setting in…
Post: Multi Column indexes vs Index Merge
September 19, 2009 By 31 Comments
…ignore combined index) mysql [localhost] {msandbox} (test) > explain select avg(length(val)) from idxtest ignore…+—-+————-+———+————-+—————+——-+———+——+——+————————————-+ 1 row in set (0.00 sec) As you can see in this case MySQL…
Post: Improved InnoDB fast index creation
November 6, 2011 By 4 Comments
… by default. Let’s look at each of the above cases in more detail. ALTER TABLE By temporarily dropping secondary indexes from… a special case of the previous one: mysql> SET expand_fast_index_creation=OFF; Query OK, 0 rows affected (0.00 sec) mysql> OPTIMIZE…’s also a number of cases when this optimization is not applicable: UNIQUE indexes in ALTER TABLE are ignored to enforce uniqueness where…
