Emergency

Search Results for: alter table modify mysql

Full table scan vs full index scan performance

Earlier this week, Cédric blogged about how easy we can get confused between a covering index and a full index scan in the EXPLAIN output. While a covering index (seen with EXPLAIN as Extra: Using …


MySQL Schema Agility on SSDs

TokuDB v6.5 adds the ability to expand certain column types without downtime.  Users can now enlarge char, varchar, varbinary, and integer columns with no interruption to insert/update/delete statements on the altered table.  Prior to this …


On Character Sets and Disappearing Tables

The MySQL manual tells us that regardless of whether or not we use “SET FOREIGN_KEY_CHECKS=0″ before making schema changes, InnoDB will not allow a column referenced by a foreign key constraint to be modified in …


Addressing Hot Schema Changes in MySQL

As ones data model evolves changing the database schema becomes painful, especially for big databases where the table must be taken offline. Fortunately, Tokutek introduced online schema changes starting in TokuDB v5.0. A typical schema change involves …


Reasons for run-away main Innodb Tablespace

So you’re running MySQL With innodb_file_per_table option but your ibdata1 file which holds main (or system) tablespace have grown dramatically from its starting 10MB size. What could be the reason of this growth and what …


iiBench Contest – Who Can Insert 1B Rows into MYSQL the Fastest?

At the recent OpenSQL Camp in Charlottesville, VA, Tokutek offered a challenge to the MySQL community – who can insert a billion rows into MySQL the fastest?  We will post the results on our website …


Filtered MySQL Replication

To get this straight – I’m not a big fan of filtered or partial MySQL Replication (as of version MySQL 5.0) – there is enough gotchas with replication itself and getting things right with filtering …


MySQL EXPLAIN limits and errors.

Running EXPLAIN for problematic queries is very powerful tool for MySQL Performance optimization. If you’ve been using this tool a lot you probably noticed it is not always provide adequate information. Here is list of …


Percona XtraDB Cluster 5.6.24-25.11 is now available

Percona is glad to announce the new release of Percona XtraDB Cluster 5.6 on June 3rd 2015. Binaries are available from downloads area or from our software repositories. Based on Percona Server 5.6.24-72.2 including all …


Testing backup locks during Xtrabackup SST on Percona XtraDB Cluster

Background on Backup Locks I was very excited to see Backup locks support in release notes for the latest Percona XtraDB Cluster 5.6.21 release. For those who are not aware, backup locks offer an alternative to FLUSH …