Pop quiz. Look at the picture below. Quick: can you tell me to which year and month partition P001 refers?


I couldn't say it without asking the database itself to revert the output of to_days:

select from_days(723180);
+-------------------+
| from_days(723180) |
+-------------------+
| 1980-01-01        | 
+-------------------+

Just to make the pain more clear, you do something like this, clean and neat, and you think you have done a good job.

CREATE TABLE t1 ( d DATE ) 
PARTITION by range (to_days(d))
(
  partition p001 VALUES LESS THAN (to_days('2001-01-01')) 
, partition p002 VALUES LESS THAN (to_days('2001-02-01')) 
, partition p003 VALUES LESS THAN …

A colleague of mine at Sun/MySQL showed me how to get
statistics from my blog. This was an interesting read
of all statistics. I noted that there was a great
interest in partitioning related information and that
the new partitioning feature mentioned in my blog
2 years ago still attracts a lot of attention.

So I thought it was a good idea to blog a bit more
about what's going on in the partitioning
development. I decided to check out how easy it is
to externalize my development trees on launchpad.
It turned out to be really easy so I simply
put up the development tree for the new partitioning
feature which I described in my last blog.

Launchpad tree

I also externalized the Worklog entry for this
development, unfortunately not a …

Well, I suppose its' true you can't use the official MySQL ALTER TABLE statement to do it, but if you're willing to trust your trigger coding abilities you can.All you need is an extra table and a couple triggers.The concept is fairly straight forward:Create a before insert trigger on the child table that validates the parent exists in the parent table.If there is no parent found, then insert a

A devilish quiz by Scott Noyes has made me thinking about a side effect of partitioning.
The quiz Given a table trickytable with a INT field, explain how these statements and results are possible:

INSERT IGNORE INTO trickyTable (id) VALUES (1);
Query OK, 0 rows affected (0.00 sec)

SELECT * FROM trickyTable;
Empty set (0.00 sec)

There are no blackhole, federated, triggers, proxy.
I initially tried with the event scheduler, with an event that empties the table every second, but the insert results in 1 row to be inserted, while the quiz asked for 0 rows.

After a few minutes, I got it. The right answer was to use partitioning.

Let me show off a bit. :)
Table trickytable was created with partitions by range or list , with a partition that does not include 1.
…

Talking with users at OSCON 2008, the biggest fear with new features was table corruption with partitioning. Until recently, this fear was substantiated by bug#20129, which reported inability of repairing corrupted partitions. The initial "fix" for this bug was to disable the offending commands.
After a while, especially when the Support department complained loudly, the bug was reopen and a proper fix implemented. Now you can maintain a partition using ALTER TABLE ... CHECK/ANALYZE/OPTIMIZE/REPAIR PARTITION.
I did some experiment, using MySQL sandbox and the employees test database, which supports partitioning.
You need to download the latest MySQL 5.1 release (5.1.28), where the patch is available.
To load the employees database …

Some months ago I helped out in another project in which they had some performance problems. They had a very big table and the index of the table was bigger than the table itself. As every change in the table causes MySQL to recalculate/reload the index, this can take some seconds for such big tables.
So, I thought it would be a good idea to split that big table into very small ones. This should reduce the overhead of reloading big indices and instead reload only very small parts. And the next thought was: Is it possible to use the "new" MySQL-Partitioning for that?
Continue reading "Is MySQL-partitioning useful for very big real-life-problems?"

mysql 5.1 is nearing release, with the present release candidate 5.1.24.

The most important new feature, in my eyes, is the new partitioning capability. When I get some time, I will write up a more complete post on my experiences so far with 5.1 partitioning, but I am going to try to keep the turnover on posts a bit higher, and post smaller things on here more regularly.

Partitioning has the potential to make large tables in mysql manageable once again. This is music to the ears of anyone that has had the misfortune of having to learn, the hard way, about MyISAM’s often painfully slow “Repair by keycache” loading and repairing of large tables with unique keys. Add that to MyISAM’s propensity to table corruption, especially with large tables, and you have a ticking timebomb on many pre-5.1 servers out there. If you are lucky, you can repair a …

At the MySQL Conference & Expo 2008, Britt Crawford and Justin McCarthy, both from Cafepress.com, gave us a very interesting talk on scaling with HiveDB. I took a few notes (pasted below), their slides are online (warning: 6.1MB PDF), and if you’re after their abstract its available as well.

I also took a video of them (refer to Slide 12, for the IRC conversation):

The quick notes:

• OLTP optimised (as it serves cafepress.com)
• Cannot lock tables, or take it offline
• Constant response time is more important than low latency (little slower query is ok, just not exponentially …

I had a great time speaking about partitioning at the MySQL conference this week.Special thanks go out to Mattias Jonsson as well for helping answer some of the questions afterwards. The room was packed - which makes me excited for the future of MySQL partitioning!I hope everyone got something out of the session, and I'd gladly welcome any comments (positive or constructive).I plan on doing some

• Phil Hilderbrand of thePlatform for Media, Inc presents
• classic partitioning
  • old school - union in the archive tables
  • auto partitioning and partition pruning
  • great for data warehousing
  • query performance improved
  • maintenance is clearly improved
• design issues in applying partitioning to OLTP (On-Line Transaction Processing)
  • often id driven access vs date driven access
  • 1 big clients could be 80% of the whole database, so there's a difficulty selecting partitioning schemes
• partitioning is only supported starting from MySQL 5.1
• understanding the …