So you have accidentally removed a datafile from your production database? First thing, DON’T PANIC! There’s an easy way to recover deleted datafiles, for as long as your database remains up. The procedure below works on linux, however this method conceivably can work for other platforms. This procedure will even work if your database is [...]

If you didn’t get your proposal in for MySQL Conference 2008 , that’s too bad.

I often wondered from past conferences why submissions were needed so early, like 5 months before. Well, as being invited to be part of the MySQL Conference committee this year I now know why, and have a greater appreciation. With near 300 submissions, it takes time to review them, and this is just the first step in a number to get to a completed schedule for next years conference.

Also getting a sneak preview of what’s to come is really cool! I’m already excited.

If you didn’t get your proposal in for MySQL Conference 2008 , that’s too bad. I often wondered from past conferences why submissions were needed so early, like 5 months before.

So I have been doing some more research about Oracle - Database-assisted Web Publishing using Java Stored Procedures from my last post and I've tried to implement it into more manageable chunks.
I mean, you can save processed data (data that has already been calculated and/or had some business/application logic applied to it) in the WebCache and then re-use it instead of contacting the database over and over again. The theory here is sound, but even in the white papers on the subject, there has been some reluctance about whether the cache hits will benefit the overall performance or hinder it.


The Downside of Caching

From my experience, its sometimes impractical to save processed data. For …

To get this straight - I'm not a big fan of filtered or partial MySQL Replication (as of version MySQL 5.0) - there is enough gotchas with replication itself and getting things right with filtering can get quite bumpy road. In some applications however it is very helpful so lets see what one should do or should not do to make it work.

Experience shared here mainly applies to logical level replication. MySQL 5.1 can use row level replication which alleviates some of these issues but I guess it will still take some time before it becomes massively used.

First thing you need to know about partial replication - you can do filtering on the Master or on the Slave. Filtering on the Slave is normally preferred as in this case you get full binary log on the Master which is not only helpful for replication needs but also if you ever need to do roll forward recovery while recovering from backup. There are however some cases when you really …

Regarding my last post MySQL Administrator useful InnoDB graphs here are the explanations of some of the graphs.

idb storage page

• reads graph: number of reads; it monitors if the system is under heavy or light read access.
• pending reads graph: number of pending read requests to the underlying data file (the database must wait to gain access). If this value increases it could indicate serious contention issue. Seeing this graph always close to the bottom line it’s very good.
• writes graph: number of writes; it monitors if the system is under heavy or light write access.
• pending writes graph: number of pending write requests to the underlying data file. If this value climbs requires attention. Seeing this graph …

I often noticed that people complain about the LOAD DATA performance when loading the table with large number of rows of data. Even today I saw a case where the LOAD DATA on a simple 3 column table with about 5 million rows taking ~15 minutes of time. This is because the server did not had any tuning in regards to bulk insertion.

Consider the following simple MyISAM table on Redhat Linux 32-bit.

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CREATE TABLE load1 (
  `col1` varchar(100) NOT NULL DEFAULT '',
  `col2` int(11) DEFAULT NULL,
  `col3` char(1) DEFAULT NULL,
  PRIMARY KEY  (`col1`)
) TYPE=MyISAM;

The table has a string key column. Here is the data file( …

Today I had an interesting issue from one of the internal property within Yahoo!, where they were not able to start the MySQL server after the server has been upgraded to 5.1 from 4.1.

Here is the error log when the 5.1.22 server has started on 32-bit RHEL:

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      071105 12:25:50  INNODB: Operating system error number 27 IN a file operation.
INNODB: Error number 27 means 'File too large'.
INNODB: SOME operating system error numbers are described at
INNODB: http://dev.mysql.com/doc/refmastartn/5.1/en/operating-system-error-codes.html
INNODB: File name /mysql/var/mysql/ibdata/ibdata1
INNODB: File …

Yep, it's true. "MySQL Toolkit" technically infringes on MySQL's trademark. I haven't been given a mandate or cease-and-desist order or anything, but as Marten Mickos (MySQL's CEO) told me, anything that starts with the word "MySQL" sounds like it comes from the company, and this project doesn't come from MySQL.

Suggestions are welcome. I'm totally uninspired. "Toolkit" was the best I could do when I named the project to begin with.

MySQL AB will be exhibiting at next week's Oracle OpenWorld event, November 12-15 in San Francisco; Moscone South Hall, kiosk booth PSP 32.

In the past year, the Independent Oracle Users Group has produced surveys of its membership that show that MySQL is an increasingly popular complementary database within Oracle customers' IT departments. Between one-quarter and one-third of IOUG members report using MySQL in their organizations today -- and a majority plan to grow their adoption of open source database technology in the next year.

For a free copy of the most recent IOUG open source survey, as well as technical MySQL resources for Oracle developers and DBAs, please visit www.mysql.com/oracle.