… performance, and BKA uses the MRR interface, so these buffers indirectly impact BKA performance. I did not find much of a performance improvement from using Hash Join in MariaDB 5.5 or from Key-ordered Scan for TPCH query #3, in fact disabling both of…
Post: Shard-Query turbo charges Infobright community edition (ICE)
May 6, 2011 By 22 Comments
…up, Shard-Query can improve performance of almost all queries …of the data, performance can be improved significantly: $ cat shards.ini [default] user=mysql db=ontime password= port=5029 column=date_id mapper=hash…join dim_date using (date_id) GROUP BY Year) t2 ON (t.Year=t2.Year); The performance of…
Post: Why MySQL could be slow with large tables ?
June 9, 2006 By 139 Comments
… bound workloads. There are certain optimizations in works which would improve performance of index accesses/index scans. For example retrieving index values first… lack of advanced join methods at this point (the work is on a way) – MySQL can’t do hash join or sort merge join – it…
Post: High-Performance Click Analysis with MySQL
December 22, 2008 By 13 Comments
…of slicing and dicing. And as a result, one of the most common questions we hear is how to build high-performance… joins on large data sets are very expensive. If MySQL supported sort-merge or hash joins,… key(day, ad, is_blue) ); What can we improve here? Especially assuming that there are indexes…
Comment: Why you don't want to shard.
August 6, 2009 By 33 Comments
… into a different category of sharding (although from a technical perspective it is method 2: sharding by hash or key). But my… decision to “migrating to another database” – there are a lot of workloads it isn’t that well suited for, and it… retrofit into an existing application. I’d like to see join performance (via hash joins) improved for example, but there are a few more issues…
Comment: Star Schema Bechmark: InfoBright, InfiniDB and LucidDB
April 11, 2010 By 46 Comments
…scenes on foreign key constraint definitions in order to improve the performance of the join. I believe that LucidDB builds such a structure on… Other engines focus on distributed hash-joins instead of materialization. Ideally, such an engine will have a high-performance way of building such a …
Post: SHOW INNODB STATUS walk through
July 17, 2006 By 40 Comments
…improve MySQL Performance. To start with basics SHOW INNODB STATUS is command which prints out a lot of internal Innodb performance…before joining …of buffers used by adaptive hash index. You can also see number of hash index lookups and number of non-hash index lookups which is indication of hash…
Post: Using CHAR keys for joins, how much is the overhead ?
June 18, 2007 By 18 Comments
… expected MyISAM to be slower due to amount of extra system calls it has to read row … gave significant improvement to 3.5 seconds which is just 20% slower than integer based join for Innodb. …sha1() hashes which still made eq join to run the same ways but gave me much longer keys. The performance …
Post: TPC-H Run on MySQL 5.1 and 6.0
April 10, 2008 By 16 Comments
…,though at least we get to see performance of individual queries. We also packaged the toolset … MySQL 6.0 performance will improve. Though considering a lot of talks about optimizer improvements in MySQL 6…. does not have hash or merge join which are frequently used for these kind of queries, and …
Post: Guidance for MySQL Optimizer Developers
September 20, 2009 By 4 Comments
I spend large portion of my life working on MySQL Performance Optimization and so MySQL Optimizer is quite important to me. … optimizer change causes a lot of pain for some of the users. Even if you improve performance 99 our of 100 queries there are going… query in optimal way – loose index scan, hash join, sort merge join are all the examples of such. For me it is most important…
