… MariaDB as a first-class member of the MySQL family of databases. Finally, High Performance MySQL, Third Edition mentions MariaDB in many places… binary log enabled Faster queries through speedier joins, faster subqueries, and elimination of useless tables in joins Thread pooling and a segmented key…
Post: Joining many tables in MySQL - optimizer_search_depth
April 20, 2012 By 6 Comments
… seconds, which points to problem with optimizer performance. Note though if you have subqueries these might need to be executed during EXPLAIN phase yet making it unusable to check the optimizer performance. Solution… Timour explanation somewhat conflicting though as if we assume MySQL users do not join lots of tables (less than 7) when using…
Post: MySQL Limitations Part 3: Subqueries
October 25, 2010 By 20 Comments
… on what’s seriously limiting MySQL in certain circumstances (links: part 1, 2). This post is about subqueries, which in some cases…-out as users expect. It’s easy to pick on subqueries in MySQL, so I’ll try to be gentle. The following… poor subquery performance, or have had it in the past and have fixed it. And many MySQL users have learned to simply write JOINs…
Post: Shard-Query turbo charges Infobright community edition (ICE)
May 6, 2011 By 22 Comments
… which helps improve the performance of queries against a MySQL database by distributing the …stage.TailNum, … from ontime_stage join dim_date using(FlightDate) join dim_airport origin on ontime_… queries show how performance is improved when Shard-Query adds parallelism when “subqueries in the from…
Post: MySQL VIEW as performance troublemaker
August 12, 2007 By 53 Comments
… assume MySQL would optimize your VIEWs same way as more advanced database systems would. Same as with subqueries and derived tables MySQL 5.0 will fail and perform very inefficiently in many counts. MySQL has two ways of… join” used to to join between them. In this particular case it is not that bad because “join cache” is used to perform it…
Post: Distributed Set Processing with Shard-Query
May 14, 2011 By 27 Comments
… the worst case for performance. Optimal mathematical performance requires operations on reduced sets…post. This allows BETWEEN, IN, subqueries in the FROM clause, and…SQL, but right now only MySQL storage nodes are supported. Amdahl…>= 0) flight_delayed from ontime_fact join dim_date on ontime_fact….
Post: Database problems in MySQL/PHP Applications
August 11, 2006 By 12 Comments
…MySQL. There are many successful applications, using tens of thousands of tables per host and archiving great performance… it does not always bring good performance. Joins are expensive and you can often …in this case. This most applies to subqueries Where Subselects with IN() become corellated …
Comment: Database problems in MySQL/PHP Applications
August 11, 2006 By 12 Comments
…data however it > does not always bring good performance. Joins are expensive and > you can often do …be called Not using > Join. This is typical error. On other hand in MySQL you might be > …queries in this case. > This most applies to subqueries Where Subselects with IN() become > corellated even …
Comment: My Innodb Feature wishes
May 13, 2006 By 30 Comments
… do with Range usage. In your case join can be only performed using two key parts. You can…rows query would return without subselect: mysql> select count(*) from Statement T join CurrDailyVal Q on Q.cur1 =… subquery will need to be executed 55mi times so do not expect fast answer even if subquery is…
Post: Extended EXPLAIN
July 24, 2006 By 9 Comments
… join `…SUBQUERY | sbtest | unique_subquery | PRIMARY | PRIMARY | 4 | func | 1 | Using index; Using where | +—-+——————–+——–+—————–+—————+———+———+——+———+————————–+ 2 rows in set, 1 warning (0.03 sec) mysql…MySQL Performance…
