… be held at Portland State University’s Smith Memorial Student Union, located at 1825 SW Broadway, Suite 327/8/9 Portland… with MySQL, then this is an event you can’t afford to miss… 
So register now! Please also join the Portland MySQL Meetup group for more MySQL-focused events in Portland If you love the ideal of Percona MySQL University and…
Post: Percona MySQL University @Portland next Monday!
June 12, 2013 By Leave a Comment
Post: MySQL 5.5 and MySQL 5.6 default variable values differences
February 21, 2013 By 8 Comments
…) value55, left(var56.variable_value,40) var56 from var55 left join var56 on var55.variable_name=var56.variable_name where var55…/dist/mysql-5.5.30-linux2.6-x86_ | /mnt/nfs/dist/mysql-5.6.10-linux-glibc2. | | MAX_ALLOWED_PACKET | 1048576 | 4194304 | | JOIN…_union=on,index_merge_sort_union=on,index_merge_intersection=on,engine_condition_pushdown=on 1 row in set (0.00 sec) mysql…
Post: How is join_buffer_size allocated?
July 5, 2010 By 9 Comments
… session join_buffer_size = 1 << 30; # 1GB select * from (select 1 union select 1) as x1 join (select 1 union select 1) as x2 join…. That should try to allocate 1GB of memory for each join. If you execute this and nothing bad happens, you might be seeing this bug: http://bugs.mysql.com/55002
Post: MySQL Indexing Best Practices: Webinar Questions Followup
August 16, 2012 By 4 Comments
… key significantly fragmented. I also would note there are some MySQL optimizer restrictions in how well it can deal with primary… is used to join the two tables? A: The question in this case is how MySQL will execute the join. If it will… complicated conditions you will need to use something like Trick “Unionizing Order by” described in presentation. Q: what is the impact…
Post: Shard-Query turbo charges Infobright community edition (ICE)
May 6, 2011 By 23 Comments
….TailNum, … from ontime_stage join dim_date using(FlightDate) join dim_airport origin on … has tens of millions of flights: mysql> select count(*) from ontime_one.ontime_fact; +———–+ | count(*) | +———–+ |…, subqueries in the FROM clause, UNION or UNION ALL clauses. If none of those …
Post: Quickly finding unused indexes (and estimating their size)
December 5, 2012 By 2 Comments
…. Then I simply created a view of a UNION DISTINCT of those two tables: mysql> create view used_indexes as (select TABLE_SCHEMA, TABLE_NAME, INDEX_NAME from master_index_stats ) UNION DISTINCT (select… ASC SEPARATOR ‘,’) as COLUMN_NAMES from information_schema.tables t join information_schema.statistics i using (table_schema, table_name) where…
Post: Distributed Set Processing with Shard-Query
May 14, 2011 By 27 Comments
… is treated as a materialized view over a union of all the already joined and aggregated data from all the nodes. A…. This allows BETWEEN, IN, subqueries in the FROM clause, and UNION operations to operate fully in parallel. Distributed set processing is… of compute resource which speaks SQL, but right now only MySQL storage nodes are supported. Amdahl’s law applies to the…
Post: Identifying the load with the help of pt-query-digest and Percona Server
December 29, 2011 By 3 Comments
…enable logging atomically, not just for new connections as in MySQL. This is very helpful for measurement as otherwise we …trx_id: F00 # QC_Hit: No Full_scan: Yes Full_join: No Tmp_table: No Tmp_table_on_disk: No # …2.5% 51 0.0039 1.00 0.00 SELECT UNION wp_pp_daily_summary wp_pp_hourly_summary wp_…
Post: How adding another table to JOIN can improve performance ?
August 1, 2008 By 12 Comments
… to this problem – using IN list instead of range or UNION which however require rather serious application changes and also can… some pre-generated table and use the join to retrieve the rows from original table: mysql> show create table dl \G *************************** 1… yet another table to the join so the info table just has bunch of ref lookups: mysql> select * from g; +—–+ | gr | +—–+ | 10…
Post: Moving Subtrees in Closure Table Hierarchies
February 14, 2011 By 18 Comments
… FROM TreePaths AS t WHERE t.descendant = ‘C’ UNION ALL SELECT ‘D’, ‘D’, 0; The above is … table in a single query in MySQL. But we can use MySQL‘s multi-table DELETE syntax, to …supertree.length+subtree.length+1 FROM TreePaths AS supertree JOIN TreePaths AS subtree WHERE subtree.ancestor = ‘D’ AND …
