… applications to avoid using Donor/Desynced nodes, particularly when using a blocking SST method like rsync or mysqldump. So, flow control kicks in… can be used to discover which node is causing flow control. I would strongly recommend monitoring and graphing wsrep_flow_control_sent so… and when flow control is happening and what node (or nodes) are causing it. Using myq_gadgets, I can easily see flow control…
Post: Using flow control functions for performance monitoring queries
May 24, 2008 By 12 Comments
… big fan on flow control functions like IF or CASE used in MySQL Queries as they are often abused used to create queries… by MySQL Optimizer. One way I find IF statement very useful is computing multiple aggregates over different set of rows in… otherwise you will not catch important but may be less used functions performance problems. Another thing you may notice I look…
Post: Using any general purpose computer as a special purpose SIMD computer
May 16, 2011 By 5 Comments
… cheap computation, our world can become an amazing place. Please use this technology constructively and for peaceful purposes. Love one another… the items. We operate on all the buckets and then use intelligent expression substitution to put the results back together, when… 1 and 1024 ) parallel_work; This allows you to use data flow semantics on any cluster with respect to almost any generic…
Post: Realtime stats to pay attention to in Percona XtraDB Cluster and Galera
November 26, 2012 By 4 Comments
… through. Using the Up and Dn columns, I could easily see which node was the originator of the transaction. Flow Flow gives some information about Flow Control events. Galera has some sophisticated ways of… Flow group. This is wsrep_cert_deps_distance — This is a general indicator of how many parallel replication threads you could use…
Post: Infinite Replication Loop
October 10, 2011 By 2 Comments
… masters. Let’ s have a look first at the normal flow: Replication flow: [1] When you setup MySQL replication, you define the… master should also replicate events : Closer look: Infinite Replication Loop flow: If you have master-master with slaves or if you… also check all the statements that were in the loop using mysqlbinlog. For example what was the loop of events from…
Post: Percona XtraDB Cluster: Failure Scenarios with only 2 nodes
July 25, 2012 By 6 Comments
… case master splits from several slaves it still remains operational. Use with extreme caution even in master-slave setups, because slaves…-d509-11e1-0800-013f68429ec1 120724 10:58:09 [Note] WSREP: Flow-control interval: [8, 16] 120724 10:58:09 [Note] WSREP…-0800-013f68429ec1 2012-07-24 11:42:51.292 INFO: Flow-control interval: [9999999, 9999999] 2012-07-24 11:42:51…
Post: Data mart or data warehouse?
July 15, 2010 By 14 Comments
… challenges with larger databases, and some ways to help performance using aggregation. Using materialized views to automate that aggregation process. Comparing the… or more data transformations is usually called a “flow“. An example ETL flow might combine data from item and category information into…
Post: MySQL net_write_timeout vs wait_timeout and protocol notes
July 8, 2007 By 1 Comment
… however comes back in multiple pieces and if you’re using mysql_use_result you can do any work between fetches, which… idea. This for example typical cause of aborted connections while using Sphinx with large data sets and large buffers. While indexing… side. You could ask why server does not do any flow control and can’t find out client just is just…
Post: MySQL Releases first real Community Release
March 18, 2007 By 2 Comments
… great but I hope the patches will be continue to flow in. In fact we have submitted our slow query log…. Same situation with Fedora Core actually was another reason to use CentOS for servers on production – Fedora Cores keep coming up… community version may be organized. Another good thing – unless you used some specific community features you should be good with self…
Post: How Percona Develops Open-Source Software
January 9, 2009 By 4 Comments
… pay attention to any preferences the donor has, or we use our judgment as to which enhancements will add the most…, this second model has not happened very often; we have used it more for Maatkit and MMM than for server patches… a reality. Where It All Begins Our open-source efforts flow from our company values. We believe that software and information…
