Metakit for Ruby - Would you want it?

ruby-talk
21

Touche’, mon capitain. :slight_smile:

I do like that better. Though sometimes I
do think in SQL. And my nightmares are
in COBOL…

Hal

···

----- Original Message -----
From: “Pit Capitain” pit@capitain.de
To: “ruby-talk ML” ruby-talk@ruby-lang.org
Sent: Monday, June 02, 2003 3:38 PM
Subject: Re: [OT] Re: Metakit for Ruby - Would you want it?

On 3 Jun 2003 at 3:36, Hal E. Fulton wrote:

What I’d really like is a new db with a proprietary
SQL version, for Ruby. They’re all somewhat incompatible
anyway, right?

Then I’d do it like:

…where foo matches /hello/i

If you’re going The Ruby Way, why not

table.select { |row| row.foo =~ /hello/i }

:slight_smile:

22

If you’re going The Ruby Way, why not

table.select { |row| row.foo =~ /hello/i }

:slight_smile:

or even:

relation.select(:field0, :field1){|tuple| tuple[:field0, :field1] ===
[/foo/, /bar/]}

i actually have something which does the above using named fields in
arrays.
it’s very cool but slower than dirt :wink:

Named fields?

Did you consider a hash (or better a Struct)?

Hal

···

----- Original Message -----
From: “ahoward” ahoward@fsl.noaa.gov
Newsgroups: comp.lang.ruby
To: “ruby-talk ML” ruby-talk@ruby-lang.org
Sent: Monday, June 02, 2003 4:08 PM
Subject: Re: [OT] Re: Metakit for Ruby - Would you want it?

On Tue, 3 Jun 2003, Pit Capitain wrote:

23

sure, i considered it, but it doesn’t work out too well (IMHO) in actual dbms
code. consider:

require ‘postgres’
pgconn = PGconn.new
sql = <<-sql
select * from very_large_table
sql
tuples = pgconn.query sql

p tuples[0].class # => Array
p tuples.size # => 42,000,000

fields = [:pk, :f0, :f1]

if time_to_wait()
tuples.map!{|tuple| {:pk => t[0], :f0 => t[1], :f1 => t[2]} }
else
require ‘arrayfields’ # http://raa.ruby-lang.org/list.rhtml?name=array-fields
tuples.fields = fields
end

tuples.map{|t| p t[:pk, :f0]}

having named fields in general makes for MUCH more readable database code,
plus most api’s give you a means to do something like

ret = pgconn.exec sql
tuples = ret.result
tuples.fields = ret.fields
ret.clear

at least postgresql does :wink:

but, unfortunately, most apis seem to return Arrays! one noticable exception
is guy’s plruby (procedural ruby for postgres) which does use hashes.
however, i’ve heard that Hashes require much more overhead than array’s, and
they also do not preserve ordering so in general i prefer Array’s for db code.
when i must map into a hash-like structure i use an RBTree so i can at least
define/enforce an ordering…

more than you wanted to know, i’m sure :wink:

-a

···

On Tue, 3 Jun 2003, Hal E. Fulton wrote:

relation.select(:field0, :field1){|tuple| tuple[:field0, :field1] === [/foo/, /bar/]}
i actually have something which does the above using named fields in
arrays.
it’s very cool but slower than dirt :wink:

Named fields?

Did you consider a hash (or better a Struct)?

–

Ara Howard
NOAA Forecast Systems Laboratory
Information and Technology Services
Data Systems Group
R/FST 325 Broadway
Boulder, CO 80305-3328
Email: ara.t.howard@noaa.gov
Phone: 303-497-7238
Fax: 303-497-7259
~ > ruby -e ‘p % ^) .intern’
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