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Graphs with MySQL

Mike Kruckenberg posted recently a tip he found to create easy text bar charts using the REPEAT function, that he found at:

http://www.squarebits.com/blog/2006/11/generate_simple.html

Today I stumbled across this link:
http://www.webcheatsheet.com/php/dynamic_image_generation.php#diagram

Which, using PHP, creates a graphical bar chart using the data in a MySQL database and a small bit of math.

Both are very neat!

New PostgreSQL Virtual Appliance Released

Hot from the Virtual Appliance Turkey Fryer, build 74 of the PostgreSQL Virtual Appliance is available for download here

This appliance features automated use of Virtual Hard disks to allow the nano sized appliance to access any size storage for its database.

This appliance provides an upgrade to PostgreSQL 8.1.4.

Enjoy.

Log Buffer #20: a Carnival of the Vanities for DBAs

Lisa Dobson has published the 20th edition of Log Buffer, the weekly review of database blogs, on her Oracle Newbies Blog. Twenty-editions-on is a good time to look back. I think I can say that Log Buffer has been quite a successful project so far. It is recognized, read, and enjoyed. Also, I’ve [...]

bug-reporting information_schema

In some situation (as described below in "how to repeat") the table_rows column
in the information_schema.tables table is not computed correctly.
The problem arise only for tables included in a merge table.

It seems that if you issue a select statement on a "merged table" the following
insert statement does not update the metadata table_rows.


How-to-repeat

First of all let's try the example showing the expected behavior



mysql> create table t1 (a int);
Query OK, 0 rows affected (0.00 sec)


mysql> create table t2 (a int);
Query OK, 0 rows affected (0.01 sec)


mysql> create table t (a int) engine=merge union=(t1,t2) insert_method=last;
Query OK, 0 rows affected (0.01 sec)


mysql> insert into t values(1),(2);
Query OK, 2 …

[Read more]
bug-reporting information_schema

In some situation (as described below in “how to repeat”) the table_rows column
in the information_schema.tables table is not computed correctly.
The problem arise only for tables included in a merge table.

It seems that if you issue a select statement on a “merged table” the following
insert statement does not update the metadata table_rows.

How-to-repeat

First of all let’s try the example showing the expected behavior


mysql> create table t1 (a int);
Query OK, 0 rows affected (0.00 sec)


mysql> create table t2 (a int);
Query OK, 0 rows affected (0.01 sec)


mysql> create table t (a int) engine=merge union=(t1,t2) insert_method=last;
Query OK, 0 rows affected (0.01 sec)


mysql> insert into t values(1),(2);
Query OK, 2 rows …

[Read more]
Covering index and prefix indexes

I already wrote in the blog as well mentioned in presentation there is often a choice you have to make between having prefix index - which can be significantly smaller in size and having index being covering index, which means query can be executed using only data from the index without reading the row itself.

Today I had a chance to do couple of experiments to see when exactly it works or does not work:

PLAIN TEXT SQL:

  1. CREATE TABLE `t` (
  2.   `i` int(11) DEFAULT NULL,
  3.   `j` char(10) DEFAULT NULL,
  4.   `k` int(11) DEFAULT NULL,
  5.   KEY `i` (`i`,`j`(5),`k`)
  6. ) ENGINE=MyISAM

Now lets see if index can be used as covering index if it has some key parts which are prefixes:

PLAIN TEXT SQL:

  1. mysql> EXPLAIN SELECT k FROM t WHERE i=5 \G
[Read more]
Webinar on MySQL Cluster using Dolphin SuperSockets

My blogging hasn't been so active lately. Mostly due to that I've been busy on
other things. One of the things that have kept me busy the last few months
is a project which I highly enjoy. I've been performing a benchmark study
of MySQL Cluster using Dolphin SuperSockets. Performance is one of my
favourite topics and a parallel database like MySQL Cluster has a wide array
of performance challenges that makes it very interesting to optimize it.

I will present the results in two webinars on the 30th Nov and 13 dec. The
webinars will also provide some input to the features in Dolphin
SuperSockets and MySQL Cluster that enables high performance and
real-time characteristics. With these changes to MySQL Cluster and using
the Dolphin SuperSockets MySQL Cluster becomes even more adapted for
all types of real-time applications.
See:

[Read more]
Webinar on Partitioning

As mentioned in an earlier post the partitioning in 5.1 has reached a level of
stability so that it can now be put to some heavier test. To spread further
insights of the new partitioning feature I'll deliver two webinars next week
and the week after that (29 nov and 5 Dec).

You'll find a reference to both from the MySQL Home Page.
http://www.mysql.com/

The first one will give an introduction to partitioning in MySQL and
describe the variants of partitioning that will be supported, which
management variants that are possible and so forth.

The second webinar is a follow-up that will do some repetition to
ensure it can be viewed stand-alone but will mainly dive a little
deeper into various areas of partitioning amongst other how it
relates to MySQL Cluster.

If Novell's patent portfolio is so significant...

David Kaefer, the director of business development for intellectual property and licensing at Microsoft, is on the record as saying a rather curious thing:

We've been very clear from the outset, and the financial realities of the deal underscore this, that Novell's patents have value. One need only go back to the late 90s with Novell's leadership in the directory space to recognize the benefits of much of the research and development that they conducted at that time.I'm sure this is true; at least, I'm sure it's true (in fact, I know so) that Novell's patent portfolio is significant. Not nearly as extensive as Microsoft's, but significant in its own right.

But let's assume David is telling the truth. If so, then Microsoft, not Novell, …

[Read more]
451 CAOS Links - 2006.11.22

Ubuntu Wins Most User Friendly Linux Distribution Award, Canonical (Press Release)

IBM sees Novell/MS deal benefiting Linux, Linux-Watch, Steven J. Vaughan-Nichols (Article)

Good karma for Red Hat, iTWire, Sam Varghese (Article)

Microsoft-Novell Honeymoon Ends, LinuxInsider, Jay Lyman (Article)

Enterprise Open Source, Line56 E-Business Blog, Simon Phipps (Blog)

Patent peace for our time?, …

[Read more]
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