… the most popular. I do not particularly like its write performance – I wrote about it before, that’s why I am… the performance is, and it really helps to observe some artifacts, as you will see in following graphs. Hardware for tests: HP… you did not attend my talk – you are welcome to join the webinar. Follow @VadimTk !function(d,s,id){var js…
Post: Testing Intel SSD 520
May 1, 2012 By 7 Comments
… this post I show the results of raw IO performance of this card. The benchmark methodology I described … case is random write asynchronous 8 threads IO, the test is done just after a secure erase operation … not attend my talk – you are welcome to join the webinar. Follow @VadimTk !function(d,s,id){…
Post: Testing STEC SSD MACH16 200GB SLC
April 25, 2012 By 7 Comments
… IO block. so my testing command line looks like: sysbench –test=fileio –file-total-size=${size}G –file-test-mode=rndwr –max-time… the performance is, and it really helps to observe some artifacts, as you will see in following graphs. Hardware for tests: HP… you did not attend my talk – you are welcome to join the webinar. Disclaimer: This benchmark is done as part of…
Post: Join Optimizations in MySQL 5.6 and MariaDB 5.5
April 4, 2012 By 2 Comments
… is further extended to improve join performance. As I told you above, when table t1 would be joined to table t2, then selected… these buffers indirectly impact BKA performance. I did not find much of a performance improvement from using Hash Join in MariaDB 5.5… to run tests to see what specific types of queries would benefit from Hash Join as compared to Nested Loop Join, but for…
Post: Enum Fields VS Varchar VS Int + Joined table: What is Faster?
January 24, 2008 By 27 Comments
… show close performance, while join performance degraded dramatically. Here is why: mysql> explain select SQL_NO_CACHE c.city from cities_join c JOIN states… do sort by state_id, though join cost still could be significant. And the last test – selecting city and name in arbitrary…, but join query performance is 30% lower. Also note the times themselves – traversing about same amount of rows full table scan performs about…
Post: JOIN Performance & Charsets
October 21, 2008 By 2 Comments
… way, the character sets used on joined columns can have a significant impact on the performance of your queries. Take the following…_cache count(`test`.`t1`.`char_id`) AS `COUNT(t1.char_id)` from `test`.`t1` join `test`.`t2` where (`test`.`t1`.`char_id` = convert(`test`.`t2`.`char… execution time, from 4.33 to 3.12 seconds. This test was performed with MySQL 5.0.67, FreeBSD 7, on a…
Post: Join performance of MyISAM and Innodb
May 29, 2006 By 6 Comments
… fit in memory and so buffer pool. I tested very simple table, having with about 20.000 …MyISAM does compression for character keys which makes it perform slower for random lookups MyISAM generally has lower … a bit better by primary key join than for secondary key join. I guess because it knows for …
Post: Using CHAR keys for joins, how much is the overhead ?
June 18, 2007 By 18 Comments
… time. OK. Lets start with first simple MyISAM table and join query performed on INT fields: CREATE TABLE `intjoin` ( `i` int(10… integer based join. So how do I read these results ? CHAR keys are indeed slower for joins compared to integer keys Performance degradation… guess any simple encoding) is significantly faster for joins compared to UTF8 These tests were preformed for in memory tables, for IO…
Post: How adding another table to JOIN can improve performance ?
August 1, 2008 By 12 Comments
JOINs are expensive and it most typical the fewer tables (for the same database) you join the better performance you will get. As… as the query using join with day list table. So we finally managed to get better performance by joining data to yet another… possible_keys: d key: d key_len: 7 ref: test.dl.myday,test.g.gr rows: 18 Extra: 3 rows in set…
Post: ORDER BY ... LIMIT Performance Optimization
September 1, 2006 By 93 Comments
… So what if you have application which can perform search on many different columns, with worse then…or “system” access type it is effectively removed from join execution (replaced with constants) and so ORDER BY…> explain select test.i from test, test t where test.k=5 and test.i=t.k order by test.k,t…
