… optimizer enhancements in MySQL 5.6 and MariaDB 5.5. This blog post is targeted at the join related optimizations introduced in the optimizer… available in both MySQL 5.6 and MariaDB 5.5. You can read more about BKA in MySQL 5.6 here and BKA in MariaDB… MariaDB with Hash Join and Key-ordered Scan disabled, and the only difference in query time is 48.78s vs 48.91s, so…
Post: TPC-H Run on MySQL 5.1 and 6.0
April 10, 2008 By 16 Comments
…in which significant regression is observed. Vadim has already Wrote about it in his MySQL 5.1 vs 6.0 in…in particular those presented in TPC-H benchmark are still subpar even with changes which are currently seen in MySQL…these results – MySQL 6.0 still does not have hash or merge join which are …
Post: Enum Fields VS Varchar VS Int + Joined table: What is Faster?
January 24, 2008 By 27 Comments
… cost of the join, which we always claimed to be quite expensive. Indeed there is no cost of the join in this case because there is really no join: mysql> EXPLAIN select SQL_NO_CACHE c.city from cities_join c JOIN states… sort pass (filesort) is required, which also makes MySQL to store Join result in temporary table to do the sort, all together makes…
Post: Why MySQL could be slow with large tables ?
June 9, 2006 By 139 Comments
… vs range scan by index: mysql> select count(pad) from large; +————+ | count(pad) | +————+ | 31457280 | +————+ 1 row in set (4 min 58.63 sec) mysql… problem in MySQL is lack of advanced join methods at this point (the work is on a way) – MySQL can’t do hash join or…
Post: Percona XtraDB Cluster Feature 1: High Availability
January 17, 2012 By 18 Comments
… point is that you can convert your existing MySQL / Percona Server into Node and roll Cluster using… be some improvements in write throughput when you run write traffic to 2 nodes vs all traffic …joins the cluster, it has to transfer data from existing node. There is three methods of SST available in…
Post: Identifying the load with the help of pt-query-digest and Percona Server
December 29, 2011 By 3 Comments
… logging atomically, not just for new connections as in MySQL. This is very helpful for measurement as otherwise…: F00 # QC_Hit: No Full_scan: Yes Full_join: No Tmp_table: No Tmp_table_on_disk: No… execution time, the number of tmp tables created in memory vs on-disk, percentage of queries that needed…
Post: Heikki Tuuri Innodb answers - Part I
October 26, 2007 By 17 Comments
… Cool. This is one of little known new features in MySQL 5.1 Q15: How frequently does Innodb fuzzy… performance boost and it would write at 100MBps vs 33MBps. Any plans to enable tuning of the… brands. Maybe in some denormalized database (for example, if ORDER and ORDERLINE tables are joined to form a…
Post: Estimating Replication Capacity
July 20, 2010 By 4 Comments
…replication thread was busy replicating events vs staying idle. Note you can …in Oracle MySQL Server. set userstat_running=1 and run following query: mysql> select * from information_schema.user_statistics where user=”#mysql…# 0% (5k) Filesort # 0% (5k) Full_join # 0% (7k) Full_scan # 0% (10k) Tmp_…
Comment: Star Schema Bechmark: InfoBright, InfiniDB and LucidDB
January 12, 2010 By 46 Comments
… of tables in the join going up as you progress from Q1 series to Q4 series. In addition there is an Aggregation/Join Cardinality… 1 million vs. 120 million rows. To understand the Query Complexity Dimension, you could find queries with similar rows being joined and… example query 1.2 in 7.91 seconds instead of 1465 seconds). http://infinidb.org/infinidb-blog/mysql-parallel-query-processing-of…
Post: Watch out for Marketing benchmarks
August 23, 2006 By 7 Comments
… sort merge join is needed and in many other advanced optimizer features. I can help in many cases to work around MySQL limitations or design application so it uses MySQL… is hard to be expert in everything, for example if I would do benchmarked of MySQL vs PostgreSQL and try my best to…
