…of original implementation which appeared in MySQL 4.0 Query Cache was designed to work with single core systems and relatively small memory…have multiple MySQL Query Cache instances hashed by query hash. It would help to reduce complexity dramatically. Fast Invalidation Right now when you update the…
Post: How multiple disks can benefit for single client workload ?
April 26, 2008 By 4 Comments
…multiple hard drives does not help if you have single query (or stream of queries…single query is executed for Innodb storage engine to be more specific. Lets look at update queries (from replication thread for example). When update…
Post: Percona XtraDB Cluster: Multi-node writing and Unexpected deadlocks
August 17, 2012 By 17 Comments
… rows in set (0.00 sec) node1 mysql> update autoinc set j=”node1″ where i = 1; Query OK, 1 row affected (0.00… rows in set (0.00 sec) node3 mysql> update autoinc set j=”node3″ where i=1; Query OK, 1 row affected (0.01… the least likely it is for a single piece of data to be written on multiple nodes at the same time, the…
Post: Distributed Set Processing with Shard-Query
May 14, 2011 By 27 Comments
…on only a single base table. Knowing this, the query result …to the multiple levels of result set reduction. Finally, Shard-Query can …SQL, but right now only MySQL storage nodes are supported. … merge optimization enabled: ON DUPLICATE KEY UPDATE `origin_airport_id`=VALUES(`origin_airport_id…
Post: Managing Slave Lag with MySQL Replication
October 12, 2007 By 15 Comments
… are multiple reasons why application falls behind and why we see those lag spikes: Slave Server Load – MySQL Replication goes in single thread… long reporting queries can have queries running for hours which stalls replication progress for this time. As MySQL Replication goes in single thread it… you normally start with query chopping making sure all your update queries are short. If you need to update 1.000.000 rows you…
Post: The Doom of Multiple Storage Engines
May 8, 2010 By 22 Comments
One of the big “Selling Points” of MySQL is support for Multiple Storage engines, and from the glance view it is indeed… MySQL allows you using multiple storage engines in the query you need to test all kinds of combination such as running multi-table update… TABLE WITH READLOCK” and hoping nobody is touching “mysql” database any more. Single Storage Engine server would be also a lot easier…
Post: Data mart or data warehouse?
July 15, 2010 By 14 Comments
…with and without aggregation over multiple MySQL storage engines at various data… category information into a single dimension, while also maintaining … Data is very likely never updated or deleted in these …bitmap indexes, table partitioning, parallel query execution, clustered tables and materialized…
Post: Investigating MySQL Replication Latency in Percona XtraDB Cluster
March 3, 2013 By 13 Comments
…the cluster as if it were single server from generic application. Right. …updates are done on multiple nodes. There is an option you can enable to get fully synchronous replication behavior: mysql…update while running my test to see how the latency is impacted: mysql> update sbtest2 set k=k+1; Query…
Post: Edge-case behavior of INSERT...ODKU
October 27, 2012 By 6 Comments
… the hardware, or the queries; really, the majority of the database was a single table with an auto…to be considered as being defined first. So, MySQL checks our INSERT, sees that the next auto…on a table with multiple unique indexes such as this one would be equivalent to “UPDATE update_test SET host…
Post: Making MySQL Replication Parallel
January 30, 2007 By 1 Comment
…queries if they are complex transactions. It should be however not as bad if we only look at single queries…multiple threads inside the server to share same transactional/lock context. In this case replication could accumulate number of queries…
