Read more about my piano recording series here.

Read more about my piano recording series here.

M4DBI is a new project I’ve been working on for the past couple months. Visit the M4DBI home page for technical details and project info. Here, I will just excerpt the Rationale statement.

I’ve worked in the past with DBI, ActiveRecord, Og, Kansas and Sequel. I also have some experience with ODBC and JDBC.

ActiveRecord is good, but it took up way too much RAM on a server where memory was not an abundant resource. I also ran into various annoying and frustrating problems. ActiveRecord didn’t always play nicely outside the realm of Rails, and I was never sure how stable my application would be after upgrading ActiveRecord.

One thing that bothered me about these ORMs was the fact that they encouraged what I thought was overusage of Ruby or Ruby-ized syntax for things that could be just as (or maybe even more?) easily and cleanly done in SQL, namely: schema definition and basic queries. I am reasonably proficient in SQL, so I considered this Rubification somewhat unnecessary, and also thought that sometimes it only obscured things because one would sometimes wonder what the underlying raw SQL was for the DDL statements or queries. Why not state it explicitly?

I also had POLS violated. Now and then I wouldn’t have a record set in memory when I thought I did (due to the maximally-delayed fetching design of Sequel); or a record which I operated on in Ruby didn’t have its changes synced to the database because I forgot to #save() it.

A general impression I got from these ORMs was that the ORM was being used to mould, contort and manipulate the database. I always thought that this was backwards; rather, the DB is the reality, and the ORM should conform to it, and convey the truth about it. Otherwise, it would be like having a camera which would alter the physical things that it was taking a picture of, instead of the camera merely being a viewport on the reality.

I realized that all I really liked about ORMs are models and the relationships between them. Otherwise, I really just wanted the low-level power and intimacy of SQL, married to the beauty of my favourite language, Ruby, topped off with these pleasant extras, models and relationships. And so M4DBI was born, as an attempt to address all the above issues.

Read more about my piano recording series here.

Wrong

window.location( "http://blog.purepistos.net" );

Right

window.location = "http://blog.purepistos.net";

A silly mistake I made recently, one which left me head scratching for a while.

Now and then, I see developers do validations, constraints and hooks using their ORM, and think to myself: “Why don’t these people use their database to do that?”

I’ve been comfortable with SQL for both queries and data definition for a long time, so I always write my all schemas and most queries in SQL, by hand. But I began to wonder: Is there really any difference between doing these things natively in the database as opposed to in Ruby? So I wrote up a modest benchmark script. Following are my findings.

I am far from being an expert in benchmarking or statistics. I would be appreciative of anyone that could point out errors in my method. I also acknowledge that the processes covered are not at all exhaustive of the many possible validations and hooks one might use.

The Test Code

• schema.sql: the data definition SQL
• models.rb: the modelling code
• better-benchmark.rb: some code to help with the statistics
• test1.rb: the actual test code
• results.txt: the full result output

In all test output, method 1 uses Ruby, whereas method 2 uses the database.

Test 1: Record creation hook

In this test I compare a before_create Ruby hook to a functional column default.

# Ruby
before_create do
  set( :time_created => Time.now )
end

-- SQL
time_created TIMESTAMP NOT NULL DEFAULT NOW()

Results

Set 1 mean: 7.756 s
Set 1 std dev: 2.373
Set 2 mean: 2.861 s
Set 2 std dev: 0.052
p.value: 1.45088891038497e-11
W: 400.0
The difference (-63.1%) IS statistically significant.

By using a database function to fill in default values on creation, I chopped my record creation time to nearly 1/3 of its original cost.

Test 2: Insertion validation

In this test, I compare validation of the length of a text field; ORM validation versus database validation.

# Ruby
validates_length_of :name, :minimum => 8

-- SQL
name VARCHAR( 255 ) NOT NULL CHECK(
  char_length( name ) > 7
),

Results

Set 1 mean: 3.772 s
Set 1 std dev: 0.993
Set 2 mean: 4.157 s
Set 2 std dev: 0.607
p.value: 0.13441884182804
W: 144.0
The difference (+10.2%) IS NOT statistically
significant.

Although the difference is substantively significant, we are informed by the statistical test that it is not statistically significant. Therefore, we cannot conclude that there is any difference between these two approaches to validation.

Test 3: Deletion hook - cascade deletion

In this test, I compare cascading a delete using your ORM versus the database.

# Ruby
before_destroy do
  Employee1.where( :company_id => pk ).destroy
end

-- SQL
company_id INTEGER NOT NULL
  REFERENCES companies2( id ) ON DELETE CASCADE,

Results

Set 1 mean: 3.581 s
Set 1 std dev: 0.836
Set 2 mean: 0.087 s
Set 2 std dev: 0.028
p.value: 1.75847735938658e-08
W: 383.0
The difference (-97.6%) IS statistically significant.

Here, the database method crushes in-Ruby cascading, having a microscopic 2.4% of the time cost of the Ruby method.

Test 4: Deletion hook - update other table

In this test, I compare the in-Ruby and in-database means of updating a table after deleting a record from another one.

# Ruby
class Post1 < Sequel::Model( :posts1 )
  after_destroy do
    author.update_post_count
  end
end
 
class Author1 < Sequel::Model( :authors1 )
  def update_post_count
    post_count = posts.size
    save
  end
end

-- SQL
CREATE RULE update_post_count AS
ON DELETE TO posts2
DO ALSO (
    UPDATE
        authors2
    SET
        post_count = (
            SELECT COUNT(*)
            FROM posts2
            WHERE author_id = OLD.author_id
        ) - 1
    WHERE
        id = OLD.author_id
    ;
);

Results

Set 1 mean: 1.801 s
Set 1 std dev: 0.230
Set 2 mean: 1.103 s
Set 2 std dev: 0.234
p.value: 2.90177782076994e-11
W: 399.0
The difference (-38.7%) IS statistically significant.

Again, the database version wins out. This time, the improvement is over 1/3 the time cost of the Ruby version.

Conclusion

The in-database method beat the in-Ruby method significantly in 3 of the 4 tests I ran. In the remaining test, the results were inconclusive (being statistically insignificant), so we are unable to reject the null hypothesis that there is no difference between the two methods in that test.

If you are after a more natural syntax, and want to stay in your programming language as much as possible, using your ORM for hooks, validations and constraints is the way to go.

But if speed is a priority, sharpen your SQL Fu so you can open up your options and harness the full potential of your RDBMS. As these test results demonstrate, most hooks and checks are better off done in your database, and not with your ORM.

Footnotes

Substantive significance is the importance, meaningfulness, or magnitude of an effect or difference. For example, a speed improvement of 100% is substantively significant, whereas a speed improvement of 0.1% is not.

CD has recently installed the CRE, so all CD bloggers will have the ability to have scripture and catechism references activated with little intervention or maintenance on their part.

Thank you for installing the CRE, CatholicDestination.com!

Reby error: string not matched
chanstats.rb:43:in `[]=’

Line 43 was:

@stats[ channel ][ :size_record ] ||= 0

which looks rather innocuous. I have a couple Hashes, one nested in the other. Or so I thought… Apparently, I had mistakenly initialized @stats with a string instead of a Hash. Testing in irb, everything becomes clear:

irb(main):001:0> s = "string"
=> "string"
irb(main):006:0> s[ 'hi' ] = 'foo'
IndexError: string not matched
        from (irb):6:in `[]='

I hope this helps people who can’t figure out why they’re getting “string not matched”.

// Java
for(
  Enumeration e = parent.getChildren();
  e.hasMoreElements();
) { 
  Element child = (Element) e.nextElement();
  // Do something with child 
}

# Ruby
parent.each_child do |child|
  # Do something with child
end

Can’t you feel the peace and contentment in this block of code? Ruby is the language Buddha would have programmed in.

Sean Russell, author of REXML, comparing Java iteration with Ruby iteration

This version has the following changes:

• A checkbox now exists in the Edit Post sidebar to deactivate or activate the CRE on a per-post basis.

Report any bugs as a comment on this post.

This version has the following changes:

• You can now use the string “[nocathref]” anywhere in the post or page content, and the CRE will not operate on any references in the post. This is in lieu of using the exclamation mark in front of each of many references.

Report any bugs as a comment on this post.

Ensoulment is important to consider because many pro-life proponents state that abortion is murder. If the conceptus has a soul at the time of abortion, then the abortion would be homicide (I don’t reckon that anyone would attempt to argue that an entity with a soul is not human). An entity’s lack of a soul might strengthen the argument that it is not human, and thereby potentially nullify the proposition that abortion is murder.

How twins come about

A web search for “how twins” produces some informative links which describe the biological processes involved in the creation of twins.

In the case of the creation of a single baby, a sperm fertilizes an egg, the egg implants, and off the whole thing goes on its way to being born. The fertilized egg is called a zygote.

Twins are formed in one of two ways. Dizygotic twins are formed when two individual sperms fertilize two individual eggs. In the case of monozygotic twins, a single sperm fertilizes a single egg, just like in the case of a single baby. At some point during early development (a point which varies from case to case), the collection of the cells of the baby splits apart, and the two resultant parts continue on, growing as two distinct people (two babies are born).

The twin ensoulment problem

Any intellectually satisfactory theory of ensoulment must be able to explain the ensoulment of monozygotic twins. There are several possible explanations, including:

1. The single zygote is ensouled exactly at the point of fertilization, and the soul also splits into two souls at the point when the zygote or blastocyst splits.
2. The single zygote is ensouled exactly at the point of fertilization, and at the time of splitting, one part retains the soul, while the second part is ensouled at that moment with a second, distinct soul.
3. The single zygote has no soul at the point of fertilization, and at the time of splitting, both parts are ensouled. Alternatively, each part is eventually ensouled some time after the split, perhaps at different times.
4. The single zygote is ensouled with two souls, and at the time of splitting, each part retains one soul.

The Catholic position on ensoulment

The Declaration on Procured Abortion (from the Sacred Congregation for the Doctrine of the Faith), published in 1974, states:

[Paragraph 13] expressly leaves aside the question of the moment when the spiritual soul is infused. There is not a unanimous tradition on this point and authors are as yet in disagreement. For some it dates from the first instant; for others it could not at least precede nidation.

A recent Catholic blog post states that there are two main theories of ensoulment:

The first is called the “immediate animation, immediate ensoulment theory”; the second, the “immediate animation, delayed ensoulment theory” (also called the “serial ensoulment theory”).

Using material from notes for a medical ethics course at the International Catholic University, the blog post concludes that the [more] Catholic position is to hold the “immediate animation, immediate ensoulment theory”, despite the often raised point that Saint Thomas Aquinas believed in a delayed ensoulment. Unfortunately, although the course notes acknowledge that the existence of monozygotic twins poses a problem for the immediate ensoulment theory, no harmonization between this theory and monozygous twinning is proposed. The issue is essentially left untreated:

Inasmuch as monozygous twinning appears to be an aberration, rather than the norm, considerations of its ensoulment may also depart from the norm.

There does not appear to be at this time an official Catholic teaching on ensoulment.

Conclusion: ensoulment is not pertinent

Given room to speculate on the ensoulment of monozygotic twins, my inclination is to believe that the zygote is ensouled with two souls at conception. Although present science doesn’t seem to permit us to determine whether a single zygote will or will not split and become twins, God himself knows. Just as a single human individual would be ensouled at the time of conception, when all of his or her potentialities have begun the processes of actualization, so would a pair of people be ensouled, even though their unitary physical form would appear to us as indistinguishable from that of a single person.

Even though an official Catholic position on ensoulment in general remains as yet unspecified, paragraph 13 and footnote 19 of the Declaration on Procured Abortion make it clear that this uncertainty and lack of knowledge do not make abortion morally licit.

[Supposing] a belated animation, there is still nothing less than a human life, preparing for and calling for a soul in which the nature received from parents is completed

[On] the other hand, it suffices that this presence of the soul be probable (and one can never prove the contrary) in order that the taking of life involve accepting the risk of killing a man, not only waiting for, but already in possession of his soul.

[Even] if a doubt existed concerning whether the fruit of conception is already a human person, it is objectively a grave sin to dare to risk murder.

This version has the following changes:

• The CRE is now compatible with sites that use other Javascript libraries, such as Prototype.
• Links in the popups now give text on hover informing the user that the links open in a new window.

Report any bugs as a comment on this post.

This version has the following changes:

• NAB and LXX now have the correct URI when referencing Psalms.
• Implementation of alternative window opening methods was completed (it was incomplete in 0.8.8).
• When configuration is set to open on click, the mouse cursor now changes to the usual “hand” icon for links.
• Some outstanding & -> & conversions were taken care of.

Report any bugs as a comment on this post.

As per comments by Aristotle A. Esguerra, I have made the following changes:

& characters are now rendered with & in query strings.

Administrators can now choose how they want external sites to load:

• in a new window via the target attribute on <a> elements;
• in a new window via Javascript;
• in the same window.

There is now support for Scripture citations from more than one chapter in the same book, such as Philippians 3:17-21; 4:1-3.

Report any bugs as a comment on this post.

[Are] there degrees or type of sins in the Holy Bible? If so, give [references] please.

The Catholic Church has constantly taught that there is a distinction between mortal and non-mortal sin. 1 John 5:16-17 supports this:

If anyone sees his brother sinning, if the sin is not deadly, he should pray to God and he will give him life. This is only for those whose sin is not deadly. There is such a thing as deadly sin, about which I do not say that you should pray. All wrongdoing is sin, but there is sin that is not deadly.

See also the Catholic Encyclopedia entry on Sin and Catholic Answers’ article on Mortal Sin. The Catechism of the Catholic Church expounds on this issue in Part Three, Section One, Chapter One, Article 8 (CCC 1854-1864), wherein these passages are cited: 1 John 5:16-17; Matthew 12:31; Mark 3:29; Luke 12:10.