postgres@tardis:~$ createdb test
postgres@tardis:~$ psql test
psql (8.4.0)
Type "help" for help.

test=# CREATE TYPE rank AS ENUM ('general', 'sergeant', 'private');
CREATE TYPE
test=# CREATE TABLE military (id SERIAL PRIMARY KEY,
test(#   name VARCHAR(128),
test(#   rank rank);
NOTICE:  CREATE TABLE will create implicit sequence "military_id_seq" for serial column "military.id"
NOTICE:  CREATE TABLE / PRIMARY KEY will create implicit index "military_pkey" for table "military"
CREATE TABLE

Notice the use of SERIAL? That’s postgres’ AUTO_INCREMENT, basically. I like it better. Next, it’s time to make a text file with some data and compress it. Here’s what I put in the file (note that the spaces between the words are TAB characters):

general Lee
sergeant  Hartman
private Pyle

And compress it with gzip, making a nice little file:

hank@tardis:/tmp$ gzip file
hank@tardis:/tmp$ zcat file.gz
general	Lee
sergeant	Hartman
private	Pyle

Now let’s actually make a named pipe for postgres to read from:

hank@tardis:/tmp$ mkfifo namedpipe

Now that we have our named pipe, let’s start reading from it:

test=# COPY military (rank, name) FROM '/tmp/namedpipe' WITH DELIMITER E'\t';

The E'\t' part means to escape characters inside the single-quoted string, turning this into an actual tab character. All that we have to do now is use zcat:

hank@tardis:/tmp$ zcat file.gz > namedpipe

Immediately, there’s some output in the psql session:

COPY 3

So, postgres says it got 3 records successfully. Yay! Now, let’s display them:

test=# select * from military;
 id |  name   |   rank
----+---------+----------
  1 | Lee     | general
  2 | Hartman | sergeant
  3 | Pyle    | private
(3 rows)

So, this is a pretty good method to read in compressed files with postgres. I’ve seen many articles that use similar methods with postgres dump files, but it’s useful for bulk delimited data loading as well, as many times it’s prudent to compress bulk data files and not extract them before loading them. See the postgres COPY page for more information about this awesome function.

Pro PostgreSQL

This talk was alright, but it wasn’t really tailored for people who hadn’t used Postgres extensively. Yet, I’m sure the notes will come in handy in the future.

Introduction to Django

This was an awesome talk. He went through designing an actual working application using Django. It turns out to be incredibly easy to quickly create a really cool application. I need to research this because it looks to me to be better than Rails.

Ubiquitous Multithreading

This talk was alright if you wanted to get an idea about the challenges of multi-threading and how Intel’s TBB solves some of them. It was interesting, and I learned a few things, but it would have been a better session than a tutorial (LONG!)

ruby extconf.rb --with-pgsql-include=/usr/include/pgsql/ --with-pgsql-version=81

Now I avoid the problems I was having before:

[root@modzer0 plruby-0.5.1]# make
make[1]: Entering directory
#...
In function ‘perm_fmgr_info’:plruby.c:116: error: ‘TopMemoryContext’ undeclared (first use in this function)
plruby.c:116: error: (Each undeclared identifier is reported only once
plruby.c:116: error: for each function it appears in.)
plruby.c: In function ‘plruby_call_handler’:
plruby.c:706: warning: unused variable ‘result’
plruby.c: In function ‘pl_compile’:
plruby.c:875: error: subscripted value is neither array nor pointer
plruby.c:876: error: subscripted value is neither array nor pointer
plruby.c:879: error: subscripted value is neither array nor pointer
plruby.c:889: error: subscripted value is neither array nor pointer
plruby.c:937: error: ‘TopMemoryContext’ undeclared (first use in this function)
make[1]: *** [plruby.o] Error 1

Now I just have to create the language in Postgres. I’m making it trusted since I don’t want anyone doing anything nasty. I might build the untrusted version later like Robby did here.

CREATE FUNCTION plruby_call_handler() RETURNS language_handler
  AS '/usr/lib/ruby/site_ruby/1.8/i386-linux/plruby.so'
  LANGUAGE C;

CREATE TRUSTED LANGUAGE 'plruby'
  HANDLER plruby_call_handler
  LANCOMPILER 'PL/Ruby';

Voila!

Procedural Languages
  Name  | Trusted?
--------+----------
 plperl | yes
 plruby | yes