… Loop Join to join two or more tables. What this means is that, select rows from first table participating in the joins are read… with table t2. This step is called the build step. After the hash table has been created, rows from table t2 are read and hash function is applied to the columns participating in the join condition and then a hash table lookup is performed, on the hash table we…
Post: Troubleshooting MySQL Memory Usage
March 21, 2012 By 3 Comments
…is allocated from OS you might not see “VSZ” going down. What you might see instead is flushing tables regularly or reducing table… allocated 0 Internal hash tables (constant factor + variable factor) Adaptive hash index 4422068288 (2039977928 + 2382090360) Page hash 127499384 Dictionary cache …
Post: How well does your table fits in innodb buffer pool ?
December 9, 2010 By 11 Comments
…what is really getting warmed up first as well as how buffer pool is affected by batch jobs, alter tables, optimize table…
Post: Tokyo Tyrant - The Extras Part I : Is it Durable?
November 10, 2009 By 5 Comments
…is Tokyo Tyrant? Well I went ahead and built a quick script that just inserted data into a TC table… is tchdbmemsync. /* Synchronize updating contents on memory of a hash database object…is actually a global transaction and locks all write operations ( used for maintenance ). What is missing here is…
Post: Why MySQL could be slow with large tables ?
June 9, 2006 By 139 Comments
…delivers great performance. What could be the reason ? The reason is normally table design and understanding …index value or range. What is often forgotten about is – depending if workload is cached or not …is lack of advanced join methods at this point (the work is on a way) – MySQL can’t do hash…
Post: SHOW INNODB STATUS walk through
July 17, 2006 By 40 Comments
… purposes and similar things. Also transaction status is reported which is basically what transaction is doing it can be “fetching rows”, “updating” …hash index is hash index Innodb builds for some pages to speed up row lookup replacing btree search with hash search. This section shows hash table…
Post: Heikki Tuuri answers to Innodb questions, Part II
November 4, 2007 By 13 Comments
… table where id=5 show innodb status: Hash table size 10624987, used cells 1, node heap has 1 buffer(s) 0.00 hash searches/s, 15979.01 non-hash searches/s HT: Strange, primary key equality searches should work through the adaptive hash index! What is…
Post: MySQL-Memcached or NOSQL Tokyo Tyrant - part 3
October 19, 2009 By 25 Comments
…memcached with Tokoyo Tyrant when using disk based hash tables it would be a compelling replacement for …. Finally, one concern you have to have is the scalability of your storage solution. As…Tokyo database formats would also be interesting. What other solutions are people interested in? …
Post: Testing InnoDB "Barracuda" format with compression
April 23, 2008 By 3 Comments
…`), KEY `site_id` (`site_id`,`published`), KEY `hash` (`hash`), KEY `forum_id_2` (`forum_id`,`is_thread_start`,`published`), KEY `published` (`published`), KEY… file for (case 1) – 43032M What if load data and indexes separately: load dump into table with default format and without indexes… (space ratio is 0.37 compare to (case 1) ) What if load data and indexes separately: load dump into table with default format…
Post: Should we give a MySQL Query Cache a second chance ?
April 10, 2011 By 63 Comments
… Cache instances hashed by query hash. It would help to reduce complexity dramatically. Fast Invalidation Right now when you update the table all…’m not quire sure if it is worth doing or if delayed invalidation is enough. Improve Manageability What is in the MySQL Query Cache…. This is especially the problem for very expensive queries. The good thing about MySQL Query Cache is it knows exactly what is needed to…
