Mythical Code

Yesterday amidst a sea of tears and in front of a hot grill I finished reading Fearless – http://fearlessnavyseal.com   I was delaying my grilling responsibilities for the evening to cram in the last few pages.  I love reading and recently I’ve been on a biography kick, I read Howard Wasdin’s biography a year or so ago, and Chris Kyle’s biography just this weekend.  All of these books, have been biographies of Navy Seals, and when on friday I saw a book titled “Fearless” the story of Seal Team Six member advertised on Amazon, I gave it a look and ended up buying it.

This book I knew would be different, the others were written by the SEALs themselves, sometimes with co-authors.  This book, Adam Brown’s story was written after he was killed in action.  I knew it would be sad, I knew it would be touching.  Even though I was armed with that knowledge, I wasn’t prepared for this book. I’ll challenge anyone to read the first two pages, and put the book down from there.  I couldn’t and I don’t think you’ll be able to either.

Put quite simply, I’ve never read anything that had that big an impact on me before.  I found myself in awe and inspired by Adam Brown in many parts of the book, and in full tears in many other parts.  The story is so unbelievable that it couldn’t be fiction.  The old adage or saying, that the Truth is Stranger than fiction is very true for this story.   I won’t give away details, and please if you have read this book do not post spoilers in the comments.   I would be lying if I said after reading this book I wouldn’t look at life at least a little differently.

It is a book about the military, it is a book about a warrior.  Most of all though its a book about humanity, the struggles and obstacles that Adam had to overcome.  Definitely read this book.

Keep tuned, and check back soon.  Perhaps Friday, at say 5-ish eastern time.  There’s big news coming to this blog.  No Hints and I’m not telling till Friday 🙂

I’ve been playing with linux recently and really enjoying it.  Quite quickly however I began looking for a good database to use in linux.  The obvious choice if you look around the internets is mysql.  Its the easy one to use, most people use it and as such there’s a ton of documentation etc..  Well for those that know me, the easiest and simplest way is not always what I choose.  So I began to look at postgresql.  PostgreSQL has more in common with databases like Oracle or DB2 than mysql, for some this is a minus but for me that’s a definite plus.  I’ve a lot of oracle experience and skills that can be applied to postgresql quite nicely.  One thing I absolutely love in postgres & oracle is the create or replace functionality for functions.  Gone are the days of if object_id(my_function) is not null…  now I can just create or replace my_function.  That’s killer in my opinion.  So now I’ve got my database (postgresql 9.0) and its time to create some tables.  This was a bit of a dilemma for me, in my native environment (oracle or sql server) I create database change scripts that safely and reentrantly ( you can run repeatedly w/o error) create the objects that are needed in a transactional manner.  But how to do this in postgresql?  Well this post is about what I’ve figured out, and how I’m currently solving that problem.

First, take a look at my postgresql github repository.  What I wanted was a way to have controlled, scripted database changes that were transactional.  They would either entirely succeed or entirely fail and leave the database unmodified.  Also the individual script files would have to have a way of saying I am change #X and I need change #Y to be present first.

Below is how I’ve accomplished this.  What this does is it applies database change 1.0.0 to a database that is of change 0.0.0  (see dbc_0.0.0 in the github rep for how schemaversion, and the initial record get put in place).  Hopefully this is of some help to someone.

create or replace function dbc_1_0_0() returns void as
$$
declare
	_old_major integer := 0;
	_old_minor integer := 0;
	_old_revision integer := 0;
	_major integer := 1;
	_minor integer := 0;
	_revision integer := 0;
	_schemaname varchar := 'my-application-name';
begin
	if exists(select 1 from schemaversion where major = _old_major and minor = _old_minor and revision = _old_revision and schemaname = _schemaname and current_version = true) then
		create sequence user_id_seq;
		create table users
		(
			userid int8 default nextval('user_id_seq') not null,
			email varchar(64) not null,
			password varchar(128) not null,
			fullname varchar(64) not null,
			created_date timestamptz not null,
			modified_date timestamptz not null,
			constraint pk_users_userid primary key (userid)
		);

		update schemaversion set current_version = false where major = _old_major and minor = _old_minor and revision = _old_revision and schemaname = _schemaname;
		insert into schemaversion
		(major,minor,revision,schemaname,installed_date,current_version)
		values
		(_major,_minor,_revision,_schemaname,current_timestamp, true);
	else
		select 'Missing prerequisite schema update ' || _schemaname || 'version ' || _major || '.' || _minor || '.' || _revision;
	end if;
exception
	when others then
	raise exception 'caught exception - (%) - when applying update %.%.% to % ', SQLERRM, _major,_minor,_revision,_schemaname;
end
$$
language 'plpgsql';
select dbc_1_0_0();
drop function dbc_1_0_0();