I have heard that there have been talks at MySQL UC on running MySQL (InnoDB) on top of XFS for better write concurrency than ext3.

Last weekend I had a chance to discuss on Twitter the xfs stack overflow problem (that became apparent this month, on x86_64 systems with 8k stack) and how it would affect (if any) MySQL servers.  If I understand correctly, the problem is that stack overflow might occur when a dirty page needs to be paged-out to xfs.

The conclusion was that for stability of MySQL running on xfs:

1. xfs should not be used on top of LVM or any other MD (i.e. software RAID, etc.)
2. xfs volumes should only contain ibdata files (that are accessed using O_DIRECT) so that the files on xfs would never exist as dirty pages within the OS

References:

• Togetter - まとめ「xfs stack overflow」 (the …

I must say this is way faster than tapping. It’s surprisingly accurate even after only a few minutes of using it

A lot of systems are relatively easy to make HA (highly available). You just slap them into a well-known HA framework such as Linux-HA and you’re done. But databases are different, especially replicated databases, especially replicated MySQL. The reason has to do with some properties that hold for many systems, but not for most databases. Most systems that you want to make HA are relatively lightweight and interchangeable, with little to zero statefulness, easy to start, easy to stop, don’t care a lot about storage (or at least don’t write a lot of data; that’s usually delegated to the database), and there’s little or no harm done if you ruthlessly behead them.

Here I listed some programming and web related books those I found important for knowledge/skills/career whatever you said. Some of the books I read completely and some books partially. But all of these books I found very helpful to increase knowledge.

PHP

How do we stream data from MySQL? Traditionally, developers have thought that they can simply use their API's cursor-equivalent object (e.g. resultset) and move through the results.
Unfortunately, this does not do streaming in most cases. Normally most client libraries (which call mysql_store_result) will read the entire result into memory, and you're just going through an already-in-memory data set. This will fail if it doesn't fit in memory.
Enter mysql_use_result - if your library can use this instead of mysql_store_result, you can then skip through the records without needing to keep them all in ram at once.
However, there is some bad news - while going through a result set in mysql_use_result, you can't do any OTHER queries on the connection. An attempt to do so generally violates MySQL's protocol and fails. So if you need to do other …

Financial services on the go - GlassFish for Fundamo and profit
Alexis recently published a new Adoption Story on how Fundamo uses GlassFish v2 and OpenMQ for its Enterprise Platform. Overview at stories entry, details in questionnaire, and an overview in this earlier short video interview.
We are always interested in more GlassFish adoption stories, both from (non-paying) users and from (paying) customers.   …

A special extended edition of Tech Messages for 2010-04-15 through 2010-04-24:

• The Onion Uses Django, And Why It Matters To Us
  I love Django too.
• Open Source Network Monitoring and Systems Management - Zenoss Blog: No Node Left Behind: Datacenter Barometer: BitNami Simplifies Stacks
• mysql-cacti-templates
  Offers complete templates and a method for adding your own. Highly recommended.
• Increase maximum size of PST files
  Microsoft Outlook …

A week or so ago at the MySQL conference, I visited one of the backup vendors in the Expo Hall. I started to chat with them about their MySQL backup product. One of the representatives told me that their backup product uses FLUSH TABLES WITH READ LOCK, which he admitted takes a global lock on the whole database server. However, he proudly told me that it only takes a lock for "a couple of milliseconds." This is a harmful misconception that many backup vendors seem to hold dear.

The truth is, this command can take a lock for an indeterminate amount of time. It might complete in milliseconds on a test system in a laboratory, but I have seen it take an extremely long time on production systems, measured in many minutes, or potentially even hours. And during this time, the server will get completely blocked (not just read-only!) To understand why, let's look at what this command actually does. There are several important parts of processing …

just managed to run the first "to-many" join inside the data-nodes.
the query correspondce to

SELECT t1.*, t2.*
FROM T1 t1
LEFT OUTER JOIN T1 as t2 on t2.pk >= t1.b

- the code inside the data-nodes is general...but incomplete (data-node later crashed)
- there is no ndbapi and no SQL,the program testing is a hard-coded c-program sending messages using the ndb-cluster wire-protocol
- the result-set is not managed (the c-program just hangs)
- hopefully converting this into usable code will be faster than last years post as ndbapi is now quite complete, and this is "only" an add-on.

for a bit more background look at my …

Latest code of MySQL Connector/Python on launchpad has support for multiple result sets when you execute a stored procedure. We also changed the way the actual result of the routine is returned to conform to PEP249.

Here is some example code: it creates a stored procedure which generates 2 result sets. You can get the result by calling next_resultset(), which is returning a MySQLCursorBuffered.

    cur = cnx.cursor()

    cur.execute("DROP PROCEDURE IF EXISTS multi")
    proc = """
      CREATE PROCEDURE multi(IN pFac1 INT, IN pFac2 INT, OUT pProd INT)
      BEGIN
        SELECT 1,'a' as FooBar;
        SELECT 2;
        SET pProd := pFac1 * pFac2;
      END""" …