… to mention counting number of links (and number number of distinct forum sites) pointing to the given URL or graphs showing number of links per… first alternative to this approach was to store duplicate data storing link to “dev.mysql.com/download/mysql-5.1.html” as links to… number of matches per language. For Domain Profile we’ve got to use even more of those features such as counting number of…
Post: 10+ Ways to Crash or Overload MySQL
November 13, 2007 By 20 Comments
… quickly by MySQL. The moment you give someone access to MySQL Server, all MySQL Security… Number – Happily now there is a limit on total number of prepared statements (max_stmt_count…Stored Procedures – How much memory can stored procedure allocate ? say can you create 1000 variables in stored…
Post: ANALYZE: MyISAM vs Innodb
September 3, 2008 By 9 Comments
…MySQL optimizer also uses number…mysql> select count(distinct c) from antest; +——————-+ | count(distinct c) | +——————-+ | 101 | +——————-+ 1 row in set (0.36 sec) mysql> select count(distinct i) from antest; +——————-+ | count…
Post: Using GROUP BY WITH ROLLUP for Reporting Performance Optimization
September 17, 2007 By 14 Comments
… total number of rows which matches our where clause. Most Simple Way Number One is to simply run two queries: mysql> select grp, count… you have relatively small number of groups which you can fetch on the application side (you can store result in temporary table… from single query ? Sure. Here is Way Number Three: mysql> select * from (select grp, count(*) cnt from dt where slack like “a%” group…
Post: Shard-Query EC2 images available
May 11, 2011 By 2 Comments
… data from 1988 to 2010′; mysql> use ontime1; Database changed mysql> show table status like ‘ontime_fact’… general, a column store performs about 8x-10x better than a row store for queries which … count (the first number is wall time, the second exec time, the third parse time). $ echo “select count…
Post: SQL Injection Questions Followup
July 26, 2012 By 2 Comments
… available soon. During my webinar, a number of attendees asked some good questions,… format: bug_id IN (?” . str_repeat(‘, ?’, count($params) – 1) . “) Good suggestion, Jonathan. Since…stored procedures extensively. They found that it was awkward because of the limits of the procedure language MySQL…
Post: Is it query which needs to be optimized ?
March 6, 2007 By 9 Comments
… so for large number of rows you’ve simply got to use different solutions, such as summary table. With MySQL 5.0… the rows. If the number of combinations is small, like in this example you can use precomputed count values with great success… not really care. In some cases you can avoid COUNT completely by storing count values in the tables, in others you can but…
Post: Make your file system error resilient
August 24, 2011 By 8 Comments
…/data Filesystem UUID: f9f7a0c3-0350-46d5-9930-29c3ac1f4b32 Filesystem magic number: 0xEF53 Filesystem revision #: 1 (dynamic) Filesystem features: has_journal ext… options you might want to tune with tune2fs: Reserved block count: 0 Number of blocks reserved for root. It often defaults to… is probably not needed for partition you store MySQL data on, as chances are MySQL server is only one doing writes on this…
Post: MySQL caching methods and tips
April 4, 2011 By 5 Comments
…MySQL query cache When the query cache is enabled, MySQL examines each query to see if the contents have been stored…pages is a good way to reduce the number of round trips to the cache. Summary tables…items are deleted. When this happens, decreasing the counts in summary tables may not be possible …
Post: Handling big result sets
June 26, 2006 By 13 Comments
…mysql_real_query / mysql_use_result or mysql_store_result, which are the same). mysqli_query with MYSQLI_STORE_RESULT (used by default) is equal mysql…store result */ $stmt->store_result(); while ($stmt->fetch()) { } printf(“Number…
