by Maciej Dobrzanski | Aug 29, 2007 | Insight for DBAs
Vadim asked me yesterday to update Microslow patch for 5.1.21, because the previous one I wrote for 5.1.20 failed to apply correctly on the new MySQL release. Imagine the expression on my face after I unpacked the sources and found out that MySQL incorporated the...
by Alexey Kovyrin | Aug 28, 2007 | Benchmarks, Insight for Developers
When we optimize clients’ SQL queries I pretty often see a queries with SQL_CALC_FOUND_ROWS option used. Many people think, that it is faster to use this option than run two separate queries: one – to get a result set, another – to count total number...
by Vadim Tkachenko | Aug 28, 2007 | Benchmarks, Insight for DBAs
I believe we wrote about this before, but this topic popups again and again. Today I’ve read opinion that if we have clause WHERE has_something=1 we should have index on column has_something (the column has two values 0 and 1). In reality the right answer is not...
by Vadim Tkachenko | Aug 28, 2007 | Benchmarks, Insight for DBAs
About year ago Peter wrote about redundant indexes and mentioned sometimes it is good to leave two indexes, even one is first part of another. I’m speaking about BTREE indexes, for example, KEY (A), and KEY (A,B). From SQL point of view KEY(A) is not needed, as...
by Vadim Tkachenko | Aug 26, 2007 | Insight for DBAs
UPDATE : Post is not actual anymore Not so long time ago I had task to update string column in table with 10mil+ rows, and, as the manipulation was non-trivial, I decided this task is good to try Stored Function. Function written – go ahead. Since 5 min I got...
by Peter Zaitsev | Aug 18, 2007 | Benchmarks, Insight for DBAs
I took the same table as I used for MySQL Group by Performance Tests to see how much MySQL can sort 1.000.000 rows, or rather return top 10 rows from sorted result set which is the most typical way sorting is used in practice. I tested full table scan of the table...
by Peter Zaitsev | Aug 17, 2007 | Insight for Developers
Jan has a good article about finding the row matching some value in the group: This is one illustration of group by limitations in SQL language which is not offset by any MySQL specific extensions,yet As you can see if you want to get one row from the group which is...
by Peter Zaitsev | Aug 16, 2007 | Benchmarks, Insight for DBAs
As you might know while running GROUP BY and some other kinds of queries MySQL needs to create temporary tables, which can be created in memory, using MEMORY storage engine or can be created on disk as MYISAM tables. Which one will be used depends on the allowed...
by Peter Zaitsev | Aug 16, 2007 | Percona Events
I noticed today if you go to Yahoo.com and type MySQL to Search field it gives you suggestions for MySQL, which are: * loading javascript arrays with mysql data * mysql performance blog * mysql download * mysql administrator download * mysql front download It may not...
by Peter Zaitsev | Aug 15, 2007 | Percona Events
Sheeri just posted a great post putting a different view on recent MySQL Community Announcements. This however raises very interesting point what MySQL Community really needs ? I think the problem is there are no single set of needs for Community which can be...
by Peter Zaitsev | Aug 12, 2007 | Insight for DBAs
I start to see applications being built utilizing VIEWs functionality which appeared in MySQL 5.0 and quite frequently VIEWs are used to help in writing the queries – to keep queries simple without really thinking how it affects server performance. Even worse...
by Peter Zaitsev | Aug 12, 2007 | Percona Events
Yesterday I ran into the article which sheds some light on FaceBook search implementation. As we’re recently a lot into search having implemented a bunch of search projects ourselves and helped number a of customers with their full text search needs I decided to...
by Peter Zaitsev | Aug 11, 2007 | Percona Events
Friends are pointing me to the article saying SpyLOG, the startup which I co-founded back in 1999 was sold the other day to the MasterHost. The amount is not disclosed but it is estimated to be $3M – amount not worth mentioning for USA market but quite decent...
by Vadim Tkachenko | Aug 9, 2007 | Percona Events
I’ve just read post http://www.planetmysql.org/kaj/?p=123 about MySQL plans of including community contributions into releases. I understand MySQL’s interest to make releases stable, and includes contributions only into development tree, but this is not...
by Peter Zaitsev | Aug 9, 2007 | Percona Events
Yesterday Kaj Published changes to MySQL Community Release Policies. I knew about them a bit in advance but now they are public I can comment a bit. In general I’m disappointed and think this is moving in the wrong direction, it also makes me to think hard if...
by Vadim Tkachenko | Aug 6, 2007 | Insight for Developers
Recently we were puzzled by question how query_cache works with column level privileges. The question was appeared as we discovered function query_cache_send_result_to_client is called before real parsing of query, so at the moment of execution the query_cache is not...
by Peter Zaitsev | Aug 1, 2007 | Insight for DBAs
I finally found a time to publish Landscape of Transactional Storage Engines slides on MySQL Presentations page , this is the talk which we gave on OSCON 2007 and which talks about current state behavior and performance properties of Innodb, Falcon, PBXT and SolidDB...
by Peter Zaitsev | Jul 27, 2007 | Insight for DBAs
Working on large upgrade of MySQL 4.1 running Innodb to MySQL 5.0 and doing oprofile analyzes we found very interesting issue of buf_get_latched_pages_number being responsible for most CPU usage. It did not look right. The close look revealed this is the function...
by Peter Zaitsev | Jul 27, 2007 | Insight for DBAs
It is true you might be better of being unaware about problems, because in this case you might not run into them 🙂 Just couple of days ago Kaj Arno told me there are issues reported with SHOW PROFILE patch available in latest MySQL Community Edition and I’ve...
by Peter Zaitsev | Jul 26, 2007 | Percona Events
Interesting enough this year people at OSCON do not show to much interest in the MySQL, and Databases for that reason. Our talk comparing performance of MySQL Storage Engines had probably 20-30 people, Monty’s talk on MySQL Source Code had about same number, and...
