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LUA

You are tired of writing your UDFs in C or never wanted to write them in C at all ? How about writing them in lua ?

LUA is

functions

As example we want to read the real startup time of the errorlog.

-- we are run with the permissions of the mysqld
--
-- let's try the read the "ready for connections" from the errorlog and look
-- for the last [Note]:
--
-- 061124 17:28:39 [Note] /usr/sbin/mysqld-max: ready for connections.

local f = assert(io.open(params[1], "r"))
local readysince = nil

while true do
        local line = f:read()

        if not line then break end

        local match = string.match(line, "^([0-9]+ [0-9:]+) %[Note%]")

        if match then
                readysince = match
        end
end …
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mylvmbackup 0.3 now released

I am happy to announce version 0.3 of mylvmbackup, a tool that performs consistent backups of a MySQL server's tables using Linux LVM snapshots.

Special thanks go to Fred Blaise, who contributed the majority of the new features that have been added to this new release:

  • It is now possible to use an external configuration file /etc/mylvmbackup.conf to store the options. This is probably more convenient than having to pass a slew of options on the command line or having to hack the script itself to change the default values. This new feature requires the Config::IniFiles Perl module to be installed, a sample configuration file is included in the package.
  • The logging to the console has been …
[Read more]
mylvmbackup 0.3 now released

I am happy to announce version 0.3 of mylvmbackup, a tool that performs consistent backups of a MySQL server's tables using Linux LVM snapshots.

Special thanks go to Fred Blaise, who contributed the majority of the new features that have been added to this new release:

  • It is now possible to use an external configuration file /etc/mylvmbackup.conf to store the options. This is probably more convenient than having to pass a slew of options on the command line or having to hack the script itself to change the default values. This new feature requires the Config::IniFiles Perl module to be installed, a sample configuration file is included in the package.
  • The logging to the console has been …
[Read more]
The joys of MySQL 5.1 (Part 2- The Current Problem)

I've been very busy testing and testing MySQL 5.1.12-beta and on the surface, it passes my tests. But first, let me set the stage as far as what we are trying to accomplish at RightMedia...

All of our adserving data is aggregated into our reporting database, which runs MySQL version 5.0.22. The database is so large, that we split it across 6 machines. Each of these machines has a similar configuration: 2 Dual core Opteron CPUs, 16GB of memory and 3 146GB 15k RPM SCSI drives in a RAID-0 set.

Here is what one of our typical tables looks like:


CREATE TABLE `network_daily` (
`entity_id` int(11) NOT NULL default '0',
`buyer_entity_id` int(11) NOT NULL default '0',
`buyer_line_item_id` int(11) NOT NULL default '0',
`seller_entity_id` int(11) NOT NULL default '0',
`seller_line_item_id` int(11) NOT NULL default '0',
`size_id` int(11) NOT NULL default '0',
`pop_type_id` …
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MySQL: great performance


Watch the number of average queries per second


Please pay attention to the load average of the server

I was astonished when I saw these numbers. Does anyone has the same MySQL performance?

The server we are talking about is a replicating slave server (double XEON processor, 1GB RAM) of www.inter.it, during AC Milan-Inter Milan match.

MySQL: great performance


Watch the number of average queries per second


Please pay attention to the load average of the server

I was astonished when I saw these numbers. Does anyone has the same MySQL performance?

The server we are talking about is a replicating slave server (double XEON processor, 1GB RAM) of www.inter.it, during AC Milan-Inter Milan match.

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 …

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