… details. Changing column types from INT to BIGINT slowed down join speed for MyISAM tables from 1.7 seconds to 3.8…. Now for SHA1 based joins I also tested few storage options. First one is LATIN1 which improved join speed from 6.1 to 4… my “short” varchar join tests for Innodb table with utf8 encoding. This caused some degradation slowing down join speed from 4.5 seconds…
Post: Using delayed JOIN to optimize count(*) and LIMIT queries
April 6, 2007 By 22 Comments
… for such result sets MySQL will perform the join even if you use LEFT JOIN so it is not needed which slows… better performance you can “Help” MySQL and remove JOIN for count(*) and do JOIN after limiting result set for retrieval queries. Lets… life you will usually have several of these so performance improvements can be even higher. CREATE TABLE `fact` ( `i` int(10…
Post: Realtime stats to pay attention to in Percona XtraDB Cluster and Galera
November 26, 2012 By 4 Comments
… # of the cluster configuration. This changes every time a node joins or leaves the cluster. Seeing high values here may indicate… really just tells you if multi-threaded replication could help improve replication speed at all. Conflct Replication conflicts, as described in my… fact, this is a sysbench test what is running full speed (these are VMs, so that’s not that particularly fast…
Comment: Air traffic queries in InfiniDB: early alpha
November 3, 2009 By 19 Comments
… cpimport be used because we have seen even a 100x improvement in speed as opposed to LOAD DATA INFILE. cpimport separators: I… this setting, InfiniDB does not take responsibility for aggregation and join steps, only scans and filters. So specifically, in this example…
Post: Why MySQL could be slow with large tables ?
June 9, 2006 By 141 Comments
…places – this may affect index scan/range scan speed dramatically. The rows referenced by indexes also … There are certain optimizations in works which would improve performance of index accesses/index scans. For …gap but I doubt it will be closed. Joins Joins are used to compose the complex object …
Post: Heikki Tuuri Innodb answers - Part I
October 26, 2007 By 19 Comments
…enough, there was some work done by DIKU students improving algorithms used for read ahead and results were significant… so that we can see the full write speed of the disk for throughput. INNODB uses fuzzy … (for example, if ORDER and ORDERLINE tables are joined to form a single table), it might make…
Comment: Database problems in MySQL/PHP Applications
August 11, 2006 By 13 Comments
…would not > expect it to beat MySQLi in speed. It is however bad idea to use > mysql…more queries per page which will make > performance improvement much smaller. Notable exception being > AJAX applications … the optimizer to use the indexes to join rows together, potentially preventing a table scan. …
Post: TPC-H Run on MySQL 5.1 and 6.0
April 10, 2008 By 16 Comments
… an hour. We can also see MySQL 6.0 improving query 20 speed dramatically, the rest of the queries is however close… be MySQL 6.0 performance will improve. Though considering a lot of talks about optimizer improvements in MySQL 6.0 I expected… – MySQL 6.0 still does not have hash or merge join which are frequently used for these kind of queries, and…
Comment: Star Schema Bechmark: InfoBright, InfiniDB and LucidDB
January 10, 2010 By 48 Comments
… memory (swap space). Stride-by-stride our already great performance improves (see your previous benchmark), only partly hindered by the OS… in MonetDB is the automatic construction of join-indices, which would speed up large numbers of join queries. Other systems then would require…
Comment: Innodb Performance Optimization Basics
November 1, 2007 By 75 Comments
… slow things down. working on it!) I’ve seen great speed improvements using just these tips alone. What I don’t see… which trigger counters of things like sort_merge_pass, full joins and tmp tables on disk so you could actually better… them to fix them. I do have 0 Select_full_join and 0 Sort_merge_passes though finally. What is most…
