[Pljava-dev] Re: Question about java in Postgresql

Acarlos wrote:

> Hi my name is Antonio Carlos, from Campos - Rio de Janeiro - Brazil,
> i?m student of science computer specialized in RBMS, and i'm trying
> write article about PostgreSQL's function written java.
> Please, help me answering some questions:
>
> 1) Why to write PostgreSQL's function in Java and not in other language?

A couple of reasons come to mind:

1. SQL 2003 defines an elaborate standard for Java SQL mappings and
several database vendors follow this standard. PL/Java for PostgreSQL is
no exception. Thus, writing in Java will give you good database vendor
independence.

2. If your middle tier is a Java application server (EJB, Servlet
engine, JSP, etc.) you already have a lot of functionality written i
Java. Some of this functionality might have a high level of database
interaction. Moving such functionality into functions executed by the
backend will decrease the protocol overhead and might improve
performance significantly. If Java is the language in the backend as
well as in the middle tier, the efforts needed for such moves typically
very small. Also, by limiting the number of languages used by an
application, you make the application easier to maintain and the source
more coherent.

3. Java has an extensive runtime library. JDBC access, XML parsers, URL
resolvers, regular expressions, logging facilities, collection packages,
etc. etc. is all part of the runtime and readily available. It's also
standardized.

4. A Modern JVM is extremely fast. While a normal C/C++ compiler can
optimize code at compile time, A JVM can continue to optimize the code
in runtime as well.

5. Java is object oriented, strongly typed, promotes
interface/implementation separation, uses an efficient garbage
collector, and is in many other respects a very modern and elaborate
language.

6. Several excellent free Java-IDE's exists.

> 2) Java is faster(run-time) than other language?

5. It depends on the application. Complex functions executing in a
long-lived JVM tends to outperform most other languages since the JVM
continuously improves the code at runtime. Short lived JVM's suffer from
startup overhead and will not benefit the same way from runtime
optimizations. So you can get all from poor performance to excellent
(faster then most other languages) depending on what you do and how you
do it.

> 3) How long time Java is support to write PostgreSQL, not just in
> pljava, but the Java language.

The JDBC client driver has been around for a while (see
jdbc.postgresql.org for more info). I'm not sure how long but several
years. The first release of PL/Java was in January this year. Another
project, the PL/J http://plj.codehaus.org has not yet reached it's first
release.

> Thanks a lot, and maybe a need to write again, if you didn?t die
> reading my email! Uh! That's email badly written!

If/when you write again, please direct your questions to the mail group
pljava-dev at gborg.postgresql.org rather than me personally. This is an
open source community and the benefits of openness works both ways. You
might get more input and answers to questions might be good reading for
others as well.

Regards,
Thomas Hallgren