MySQL, High Availability and other goodies…

For some reason I never was that excited about trying to accomplish these sorts of things in Perl:

1..rand(256)).inject("") {|string,n| string + ('a'..'z').to_a[rand(25)] }

This generates a string from 1 to 256 characters long, containing random letters from 'a' to 'z'.  

Normally, I wouldn't use something that's quite so unreadable, but I'm starting to like Ruby's way of taking what should be a very simple operation that I might have done in 3-5 lines in Perl and boiling it down to a single line.

I created my Events to handle adding new partitions (and removing old ones) from my log table and they seem to be working.  However, today I noticed that the events ran a few hours later than they ran yesterday.  

          EVENT_TYPE: RECURRING
          EXECUTE_AT: NULL
      INTERVAL_VALUE: 1
      INTERVAL_FIELD: DAY
            SQL_MODE: 
              STARTS: 2008-02-13 05:36:21
                ENDS: NULL
              STATUS: ENABLED
       ON_COMPLETION: NOT PRESERVE
             CREATED: 2008-02-13 05:36:21
        LAST_ALTERED: 2008-02-13 05:36:21
       LAST_EXECUTED: 2008-02-14 07:32:22

I want to create a log table in 5.1 that is partitioned by day.  I want to roll-off old data and create new partitions for each day automatically.  Without writing a script and a cronjob, it seems like this should be possible with Events.  Let's start with the table:

create table log (
    logged datetime not null,
    id int not null auto_increment,
    text varchar(256),
    PRIMARY KEY ( logged, id )
)
PARTITION BY RANGE( TO_DAYS( logged ) ) (
    PARTITION p20080206 VALUES LESS THAN (733444),
    PARTITION p20080207 VALUES LESS THAN (733445),
    PARTITION p20080208 VALUES LESS THAN (733446)
);

I've completed a beta implementation of my take on the replication pre-cache tool. Sorry — nothing to download yet; I have to get it through an internal committee at Yahoo before I can release it (and you can imagine things are kind of crazy here). I wrote it myself because:

1. I had it mostly done before I found out there were other versions out there
2. I have to maintain it inside of Yahoo anyway
3. I wanted to learn Ruby 🙂

It's just over 250 lines of Ruby, my new favourite language and fairly compact. It doesn't use the Ruby Mysql library, rather just IO.popen calls to the mysql command line client. I did this for two reasons:

1. I haven't figured out the “right” way to deploy ruby gems at Yahoo yet (it's complicated).

Thanks to those who tried it out and left feedback, much appreciated.