… BKA With this optimization the idea of MRR is further extended to improve join performance. As I told you above, when…_orderdate < '1995-03-09' and l_shipdate > ’1995-03-09′ group by l_orderkey, o_orderdate, o_shippriority order by revenue…
Post: Should MySQL Extend GROUP BY Syntax ?
August 17, 2007 By 11 Comments
… finding the row matching some value in the group: This is one illustration of group by limitations in SQL language which is… columns, something like SELECT MAX(Population), City, Country FROM City GROUP BY Country GROUPORDER BY Population DESC; This could give you…) in the population column: SELECT City, Population City FROM City GROUP BY Country GROUPORDER BY Population DESC would simply return city…
Post: A workaround for the performance problems of TEMPTABLE views
May 19, 2010 By 7 Comments
… = 10 group by c1; +——+———-+ | c1 | count(*) | +——+———-+ | 10 | 130 | +——+———-+ 1 row in set (0.01 sec) We can use EXPLAIN EXTENDED to see… to include the restriction: mysql> explain extended select c1, count(*) from v1 where c1 = 10 group by c1; +—-+————-+——-+——+—————+——+———+——-+——+———-+————————–+ | id | select_type | table…
Post: Copying InnoDB tables between servers
July 31, 2009 By 10 Comments
…_path = ibdata1:10M:autoextend xtrabackup: innodb_log_group_home_dir = ./ xtrabackup: innodb_log_files_in_group = 3 xtrabackup: innodb_log_file_size… set global innodb_expand_import=1; to put XtraDB into extended import mode, and now we need to create empty table… can see progress of import in error.log InnoDB: import: extended import of testexport/order_line is started. InnoDB: import: 2…
Post: Shard-Query adds parallelism to queries
November 15, 2010 By 16 Comments
… not open source. In the future, Shard-Query can be extended to other database servers such as PostgreSQL or Firebird fairly… this test is to demonstrate that Shard-Query works with GROUP BY and other constructs. Q1 – SELECT count(*) from ontime.ontime… WHERE FlightDate BETWEEN ’2000-01-01′ AND ’2008-12-31′ GROUP BY DayOfWeek ORDER BY c DESC; Q3 – SELECT Origin, count…
Post: Pacemaker, please meet NDB Cluster or using Pacemaker/Heartbeat to start a NDB Cluster
May 19, 2010 By 9 Comments
… am not considering the SQL nodes but given the framework, extending to SQL nodes is trivial. Installing Pacemaker and Heartbeat is… ndb node group is available. If you have multiple ndb node groups, you’ll need one clone set per node group. The ndb…
Comment: Implementing Parallel Replication in MySQL
November 16, 2010 By 3 Comments
… such information in a different way), it is possible to extend the approach to have less restrictions, eg. parallel application of… “full independece” approach, I think it is fundamentally harder to extend it later; it seems we will be stuck with consistency… be combined with one of the patches that implement/fix group commit). The drawback that a slow transaction in one database…
Page: Tools
May 30, 2008 By 31 Comments
…. Must know and have for any MySQL User. mysqladmin mysqladmin extended -i100 -r is very nice way to look how MySQL… which would look at status variables same as mysqladmin extended but will group them together nicely and provide some hints on what…
Post: How Percona strives to remain neutral and independent
March 21, 2011 By Leave a Comment
… of our name. We can separate customers into two main groups of interest for this blog post: customers who might be… or service to other Percona customers. We will call these groups “vendors,” and variously “consumers” or “prospects” at times for brevity… obligated to get your approval before publishing (although we often extend the courtesy of sending drafts for review before publishing). Being…
Post: Percona Server 5.1.53-12.4
December 29, 2010 By Leave a Comment
… report row numbers due to a change in the slow_extended patch. (Alexey Kopytov) The Release Notes for this and previous…. For general questions, use our Percona Discussions Group, and for development questions our Percona Development Group. For support, commercial, and sponsorship inquiries…
