…is less functional and somewhat lower quality. And this choice is not because it is “free” as in “a … among all buzz, but you can find some grains of truth in the article “Dead database walking: MySQL’… in the MySQL market and your product is under proprietary license (not an Open Source one) you set …
Post: Virident vCache vs. FlashCache: Part 1
May 16, 2013 By 3 Comments
… set of utilities designed to provide functionality similar to that of FlashCache. In particular, Virident engaged Percona to do a usability and feature-set… appears that they do not. I find the vCache implementation more useful than the one present in FlashCache. Winner: vCache. Although nobody…
Post: How to find MySQL queries worth optimizing ?
September 11, 2012 By 6 Comments
…digest report it is easy to find slow queries or queries which … 2 rows in set (0.00 sec) In this case we have 2 rows analyzed for each row set… think about in this case is removing group by and aggregate functions. Then query would…
Post: Using flow control functions for performance monitoring queries
May 24, 2008 By 12 Comments
…I find IF statement very useful is computing multiple aggregates over different set of rows in … 15 rows in set (5.87 sec) In this example I hid some rows to obfuscate some date 
In …in about 95% while profile page in less than 60% – It is very important to do such grouping by user functions…
Post: MySQL Performance - eliminating ORDER BY function
October 17, 2007 By 6 Comments
… filesort 1 row in set (0.00 sec) If you take a closer look to WHERE clause you will find the reason – date…. Note in this case MySQL Optimizer is rather smart and is able to do this even if we have function in ORDER BY and exactly the same function is equals to constant by WHERE clause…
Post: Stored Function to generate Sequences
April 2, 2008 By 17 Comments
…it somewhere I did not find it with two minutes …// create function seq(seq_name char (20)) returns int begin update seq set…seq(‘one’) | +————+————+————+————+ | 102 | 1002 | 103 | 104 | +————+————+————+————+ 1 row in set (0.00 sec) I …
Post: MySQL opening .frm even when table is in table definition cache
November 21, 2011 By 8 Comments
… of MySQL with 100 tables and the table_definition_cache set to 1000. My understanding of this is that MySQL won… above strace shows. In MySQL 5.5 you can find in sql/datadict.cc a function named dd_frm_type(). In MySQL 5.1, for some reason yet unknown to humans, it lives in…
Post: Multi-Column IN clause - Unexpected MySQL Issue
April 4, 2008 By 21 Comments
…we index CRC32 of the URL which allows to find matching urls quickly. There is a bit of …in set (0.00 sec) As you can see just using multiple column IN makes MySQL to pick doing full table scan in…not. It however does not happen in our case as url_crc is functionally dependent on url so both queries…
Post: How expensive is a WHERE clause in MySQL?
October 31, 2008 By 17 Comments
…add to a MySQL query? To find out, I set my InnoDB buffer pool to 256MB …cache count(*) from t; +———-+ | count(*) | +———-+ | 8388608 | +———-+ 1 row in set (5.23 sec) I repeated this ten times… as I found out some time ago, some date functions are faster than others. That would be …
Post: Estimating Replication Capacity
July 20, 2010 By 4 Comments
… So here comes the catch in many systems – we find system is in need for optimization when replication …it: 1) Use “UserStats” functionality from Google patches, which is now available in Percona Server and MariaDB. … 0 EMPTY_QUERIES: 0 1 row in set (0.00 sec) In this case CONNECTED_TIME is 446 second…
