On an entirely unrelated note to the MySQL protocol discussions happening yesterday, the MySQL protocol is now the default protocol in Drizzle as of Monday’s tarball (3/15). Drizzle supports a limited version of the MySQL protocol, only supporting the subset of commands Drizzle cares about (no server-side prepared statements, replication, or deprecated commands due to SQL query equivalents). Not all MySQL clients have been fully tested with it, but our entire test suite is using it now with the libdrizzle MySQL implementation. The latest release of libdrizzle also includes defaulting to the MySQL protocol and port for Drizzle …

Just a quick bit of news to let you all know that additions to the standard Kontrollbase and Kontrollkit userguides are being halted while we migrate the documentation to a new wiki system run by the very nice Trac software. You will be able to access the Kontrollbase and Kontrollkit documentation at http://wiki.kontrollsoft.com when it [...]

I have been talking about this for a while, now at last I have found the time to get started! Below is a picture from my 2008 MySQL User Conference presentation. It illustrates how engine level replication works, and also shows how this can be ramped up to provide a multi-master HA setup.


What I now have running is the first phase: asynchronous replication, in a master/slave configuration. The way it works is simple. For every slave in the configuration the master PBXT engine starts a thread which reads the transaction log, and transfers modifications to a thread which applies the changes to PBXT tables on the slave.

Where to get it

I have pushed the changes that do this trick to PBXT 2.0 on Launchpad. The branch to try out is …

I use it in Oracle and notice there are 10 days missed, for example:

ORCL> select to_date('4/10/1582','dd/mm/yyyy') SHOW_DATE from dual

SHOW_DATE -------------- 04/10/1582 ORCL> select to_date('4/10/1582','dd/mm/yyyy') + 1 SHOW_DATE from dual

SHOW_DATE -------------- 15/10/1582 Say What? the date after 4/10/1582 is 15/10/1582.

But in MySQL i try it but i didn't see this case, example:

mysql

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Mark Callaghan asks Can a protocol be GPL?, after finding a disturbing comment in a source file: Any re-implementations of this protocol must also be under GPL, unless one has got an license from MySQL AB stating otherwise.
I recall talking with one of the company lawyers about this matter, and he assured me that the GPL can't be used for a protocol, and that's why this notice was dropped from MySQL.com site a few years ago, even before the Sun acquisition.
This is thus an embarrassing piece of ancient history (which will hopefully be removed soon) that has been in our files for long time. For how long?
If we get the source trees from the public bazaar …

1. Common MySQL Queries -- a useful reference.
2. MySociety's Next 12 Months -- two new projects, FixMyTransport and "Project Fosbury". The latter is a more general tool to help people organise their own campaigns for change.
3. riak -- scalable key-value store with JSON interface. (via joshua on Delicious)
4. Notes from NoSQL Live Boston -- full of juicy nuggets of info from the NoSQL conference.

…

You can store things for later! drizzle> select libtcc("#include <string.h>\n#include <stdlib.h>\nint foo(char* s) { char *a= malloc(1000); return snprintf(s, 100, \"%p\", a); }") as RESULT;

+-----------+
| RESULT    |
+-----------+
| 0x199c610 |
+-----------+
1 row in set (0 sec)

drizzle> select libtcc("#include <string.h>\n#include <stdlib.h>\nint foo(char* s) { char *a= 0x199c610; strcpy(a, \"Hello World!\"); strcpy(s,\"done\"); return strlen(s); }") as result;

+--------+
| result |
+--------+
| done   |
+--------+
1 row in set (0.01 sec)

drizzle> select libtcc("#include <string.h>\n#include <stdlib.h>\nint foo(char* s) { char *a= 0x199c610; strcpy(s, a); return strlen(s); }") as result;

+--------------+
| result       |
+--------------+
| Hello World! |
+--------------+
1 …

So, just in case that wasn’t evil enough for you… perhaps you have something you want to know the MD5 checksum of. So, you could just do this:

drizzle> select md5('Hello World!');
+----------------------------------+
| md5('Hello World!')              |
+----------------------------------+
| ed076287532e86365e841e92bfc50d8c |
+----------------------------------+
1 row in set (0 sec)

But that is soooo boring.

Since we have the SSL libs already loaded into Drizzle, and using my very evil libtcc plugin… we could just implement it in C. We can even use malloc!

drizzle> SELECT LIBTCC("#include …

Previously, in “Thoughts on Thoughts on Drizzle” I theorized that one of the major reasons why we did not see lots of people jumping at stored procedures in MySQL was that it wasn’t in their native language (for lack of a better term). We’ve seen External Language Stored Procedures for MySQL that let you write stored procedures in some other languages…. but I felt something was missing.

Firstly, I wanted a language I was really familiar with and comfortable writing complex things in.

Secondly, it should be compiled so that it runs as fast as possible.

Thirdly, it shouldn’t just be linking to a pre-compiled library (drizzle function plugins do that …