…query is only selecting on vendor, will the index have any impact on the speed of the query? A: If…MySQL Server will not automatically define any indexes for you. Hopefully your CMS already comes with reasonable set of indexes, if…sorting optimization, for more complicated conditions you will need to …
Post: Shard-Query turbo charges Infobright community edition (ICE)
May 6, 2011 By 23 Comments
…Query over Hive is that it works with existing MySQL data sets and queries. Another advantage is that it works with all MySQL…queries feature at least one join, and many of the filter conditions…query. . Query details: — Q1 SELECT…
Post: Flexviews - part 3 - improving query performance using materialized views
April 4, 2011 By 20 Comments
…mview_table_alias: c mview_join_condition: USING (customer_id) mview_join_order: 999 …), then the query would take significantly longer (40+ minutes): mysql> SELECT -> customer_id as `customer…is usually obtained with flexviews.get_uow_id_from_datetime() function. If you pass…
Post: Join Optimizations in MySQL 5.6 and MariaDB 5.5
April 4, 2012 By 4 Comments
… means many point queries, say for example if table1 yields 1000 … algorithm works best for highly selective queries, and obviously when the …made on MySQL 5.6 config: optimizer_switch=’index_condition_pushdown=off’…query time is for MySQL 5.6 which takes 0.16s less as compared to MySQL 5.5 While with…
Post: Multi Range Read (MRR) in MySQL 5.6 and MariaDB 5.5
March 21, 2012 By 10 Comments
…Multi Range Read With traditional secondary index lookups, if the columns… in the MySQL config: optimizer_switch=’index_condition_pushdown=off’ optimizer…queries with MRR are performing badly. The interesting thing is that though both MariaDB and MySQL…’s job to select the best query execution plan. I …
Post: MySQL 5.5 and MySQL 5.6 default variable values differences
February 21, 2013 By 8 Comments
…MySQL 5.5.30 and MySQL 5.6.10 to the different tables and ran the query: mysql [localhost] {msandbox} (test) > select… If you’re using innodb_thread_concurrency this will reduce overhead associated with …condition_pushdown=on 1 row in set (0.00 sec) mysql [localhost] {msandbox} (test) > select *…
Post: Getting around optimizer limitations with an IN() list
January 9, 2010 By 9 Comments
… queries are problematic in MySQL, it’s best to show some execution plans on dummy data: EXPLAIN SELECT …condition! The reason for this is simply a missing feature of the MySQL optimizer – and it has to do with… difficult to maintain. If you really want to do these types of queries, you should give …
Post: MySQL 6.0 vs 5.1 in TPC-H queries
March 25, 2008 By 17 Comments
…write about is queries that execute slower in new MySQL 6.0 version. Query is pretty simple SELECT sum(l_… Index condition‘, what I was able to find is Baron’s bug with no mention in MySQL 6.0…here is that MySQL is wrong choosing index scan here. If we try to execute query with IGNORE KEY (li…
Post: Percona XtraDB Cluster: Failure Scenarios with only 2 nodes
July 25, 2012 By 6 Comments
…with pc.ignore_sb=true: When the quorum algorithm fails to select a Primary Component, we have then a split-brain condition…mysql> insert into percona values (0,’percona1′,’jaime’); Query OK, 1 row affected (0.02 sec) percona1 mysql> select…
Post: Using any general purpose computer as a special purpose SIMD computer
May 16, 2011 By 5 Comments
…handle the output of each input asynchronously, if you like. Right now I believe this… as run by the native database interface (MySQL): mysql> select word, md5(word), md5(reverse(word)), count(*)… the query with BETWEEN 1 and 6 added to the where clause. This creates boundary conditions for our query….
