… in the Host column; there you’ll see a hostname followed by a port number. That is the port number of the TCP connection… still stumped as to how a SELECT-only transaction can possibly have undo log records! The greater moral of this story is… the developers fix them 
I’ve seen dozens of instances of those two types of problems bringing everything on the system to a…
Post: How to debug long-running transactions in MySQL
March 8, 2011 By 6 Comments
Post: How much memory Innodb Dictionary can take ?
May 6, 2010 By 3 Comments
…of memory Innodb will require for its data dictionary depends on amount of tables you have as well as number of…an option to restrict that limit. So how much memory can it really take ? …numbers will change a lot depending on your table structure – This given schema had many tables with 50+ columns…
Comment: Why MySQL could be slow with large tables ?
July 6, 2007 By 141 Comments
… and absurd number of columns (some tables have > 900!!) and the number of rows are also in the couple millions. I do data-mining of these… data at users PC (due to increase in computational power of current PC) (select a, join b, where c…) eg: select… and not the server. My current issue is how to get it out of the MSSQL server and into the SQLite DB…
Comment: MySQL 5.5.8 and Percona Server: being adaptive
February 6, 2011 By 25 Comments
… versions of MySql had a size restriction of 4GB per table. So does MySql 5.5.8 has any such restriction? 2.) How many Schema’s can we prepare in MySql 5.5.8? 3.) Is there any limit for number of Columns a table…
Post: How fast is FLUSH TABLES WITH READ LOCK?
April 24, 2010 By 30 Comments
… -A, and it’s trying to get a list of tables and columns in the current database for tab-completion. Note also… of this command is the duration during which the lock is held. The lock is released with UNLOCK TABLES or a number of other commands. Most backup systems that use FLUSH TABLES WITH READ LOCK are performing a relatively short operation inside of…
Comment: How number of columns affects performance ?
September 29, 2009 By 12 Comments
I had been meaning to test this issue (how the number of columns affect the performance) for quite some time now – and I thank you for saving me the trouble
Post: MySQL Quality of old and new features
October 4, 2007 By 24 Comments
…of days our team was pointed to number of bugs in MySQL 5.0 which again seriously shakes…Let me just take couple of bugs as examples: Triggers broken with auto-increment columns for Innodb tables (bug 26316…. So how it happened so it was not caught ? I believe the problem is serious lack of concurrent…
Post: Multi Range Read (MRR) in MySQL 5.6 and MariaDB 5.5
March 21, 2012 By 10 Comments
… of ‘pk_column‘ which is a part of the secondary key tuple, a point primary key lookup is made against base table, the number of these point primary key lookups will be depend on the number of rows that match the condition ‘key_column=x’. You… 5.6 is also reporting increased numbers for the counter Handler_read_key. This is because of how status counter values are incremented…
Post: ANALYZE: MyISAM vs Innodb
September 3, 2008 By 9 Comments
… not use index cardinality data at all but will estimate number of rows during query execution. I typically look at ANALYZE TABLE… bit of time to run (even for this very small table) this is because ANALYZE does index scans to find number of exact… see the difference let me set column “c” to NULL in both tables and see how values change: mysql> update antest set…
Post: Heikki Tuuri Innodb answers - Part I
October 26, 2007 By 19 Comments
… be allocated) Question: How much space InnoDB allocates for each blob outside of the page? HT: For each column that InnoDB needs to… performance tuning in heavily concurrent environments. Sets the max\ imum number of threads allowed inside InnoDB. Value 0 will disable the thread… second. PZ: We’ve helped number of users who had serve regressions in 5.0 because of group commit being broken. Most do…
