…. I recently had to work with many customers having large number of connections opened in MySQL and although I told them this was not optimal… number of idle connections was varied from 0 to 1500. I was expecting an influence, because those idle threads are presents in internal MySQL…
Post: MySQL Limitations Part 4: One thread per connection
October 27, 2010 By 14 Comments
…). This post is about the way MySQL handles connections, allocating one thread per connection to the server. MySQL is a single process with multiple… large number of application servers can lead to a situation where the database server has a very large number of connections open to it, most of which…
Post: 10+ Ways to Crash or Overload MySQL
November 13, 2007 By 20 Comments
…by opening transaction and doing a lot of updates, or simply keeping transaction open …by simulating number of failed connections. This can be avoided by having high max_connect_errors…of virtual hosting companies offering MySQL access. Sure they do and many of them are lucky having users using MySQL…
Post: How to debug long-running transactions in MySQL
March 8, 2011 By 6 Comments
…a long-running transaction. If a transaction remains open for a very long time without committing,… followed by a port number. That is the port number of the TCP connection that’s to blame… port ${port} > /root/tcpdumps/`date +%s`-tcpdump & mysql -e ‘show innodb status\Gshow full processlist’ > /root/…
Post: MySQL Prepared Statements
August 2, 2006 By 19 Comments
… it from same connection or multiple connections. Do not forget to close prepared statements – Many memory leaks reported in MySQL Server turned out… track number of open statements diretly. You can also adjust max_prepared_stmt_count variable which limits how many statements can be open at…
Post: Should we give a MySQL Query Cache a second chance ?
April 10, 2011 By 63 Comments
…_cache_ttl as session variable, which is very helpful for connections opened to the slaves, which would allow to read old data… multiple connection requesting the same item. What MySQL will do ? It will allow all of them to execute concurrently and when one of them… can be done for rather large set of applications. Many applications in MySQL have very large number of queries doing updates through primary key…
Post: Are PHP persistent connections evil ?
November 12, 2006 By 31 Comments
…connections with MySQL. With modern systems you can have thousands of Connections with MySQL, it however might not be overly efficient – managing large number of… still keeping MySQL connection open, others will serve static content such as images which also does not need MySQL connection open. In …
Post: How Percona does a MySQL Performance Audit
November 24, 2008 By 17 Comments
… a MySQL server. The first step is to log into the machine via SSH and open … something is disconnecting ungracefully (without closing the connection properly). This is happening 6 times every …of the analysis we do. A lot of times, customers will tell us up front to limit the work to some number of…
Post: Scaling problems still exist in MySQL 5.5 and Percona Server 5.5
May 20, 2011 By 11 Comments
…responsible for large portion of the load in … is a great headline numbers. If we look at…open_with_no_init_func,row_sel_get_clust_rec_for_mysql,row_search_for_mysql…mysql_select,handle_select,execu te_sqlcom_select,mysql_execute_command,mysql_parse,dispatch_command,do_command,do_handle_one_connection…
Post: Apache PHP MySQL and Runaway Scripts
May 20, 2008 By 20 Comments
… terminated after certain amount of seconds: Unlike set_time_limit() which specifies cpu time, pcntl_alarm() specifies number of wall clock seconds and… to do some cleanup work – for example you can open another MySQL connection to kill the query which was running (otherwise query may…
