Re: JDBC driver - first impressions and comments

On Wed, 2002-12-04 at 13:19, j.random.programmer wrote:
> Folks:
>
> Having used mysql for some time, I decided to try
> postgres 7.3. I thought I'd post some initial jdbc
> specific comments and initial impressions. Some of the
> issues that I mention may be known and/or fixed in
> development versions of the driver; therefore please
> treat this post as a "newbie's" point of view.
>
> Let me start by saying that I am writing a java based
> db object/abstraction layer that can examine any
> database and generate various java objects an
> interface to those objects. Automatic validation,
> application caching etc., will also be provided. For
> this code to work, I need to get a lot of meta-data
> about the database, tables and fields.
>
> **NOTE**
> For purposes of discussion, "md" in the following
> examples will refer to reference to a
> DatabaseMetaData object.
>
> I feel there is a definite difference between the
> mysql JDBC driver and the postgres one. The postgres
> driver is the lastest compiled driver for JDK 1.4
> against postgres 7.3
>
> 1) postgres' JDBC does not *seem* to have a "owner" or
> a person finally responsible for the driver. (at least
> I haven't found this going thru the archives). This
> simply may be how jdbc development is done by many
> people but ultimately someone has to be responsible
> for it. That somone then should be mentioned as the
> contact person for all JDBC development requests and
> bug reports.

postgres in general does not have owners, for any part of it. There are
maintainers, but nobody "owns" sections of code.
One thing to keep in mind is that postgres is one of the oldest open
source projects so the model is quite robust.

That being said, I am one of the maintainers, but certain people on this
list have adopted certain sections of the code. As a maintainer Barry
and I manage patches.

>
> 2) The jdbc compliance test results page has not been
> updated for quite some time. It's not clear how
> compliant the latest drivers are and if they are ready
> for serious production use.

As stated by others, many people myself included use the driver in
production environments.
>
> 3) I am getting exceptions when I call the following
> methods:
>
> md.supportsSavepoints()
> md.supportsGetGeneratedKeys()
>
> 4) The md.getColumnInfo() returns "int2" and "int4"
> for the TYPE_NAME field in the result set
> (corresponding to columns defined as smallint and
> integer). These should be "smallint" and "integer"
> instead.
Kris already addressed this, and in many cases the spec is vague
>
> 5) The md.getColumnInfo() returns a result set in
> which the columns are sorted by column *name* and not
> by the ORDINAL_POSITION field. This is opposite of the
> JDBC spec which requires that columns be sorted by the
> ORDINAL_POSITION field. If I create a table such as:
>
> create table foo ( zoo int, abc int, baba timestamp);
>
> I should get my columns in the following order: [zoo,
> abc, baba] but getColumnInfo() returns them as: [abc,
> baba, zoo]
>
> Note, getColumnInfo() does return the correct
> ORDINAL_POSITION data each column but sorts them by
> alpha - which is wrong. Moreover, all returned
> columns are in all-lowercase [this may be the correct
> behavior - I don't know, but if I create a column
> fooBAR, JDBC returns that as foobar].
The server itself does not create the column fooBAR, but foobar, unless
your coerce it.

> 5) The md.getImportedKeys() and md.getExportedKeys()
> methods take 30-50 seconds to return. There is
> something very strange going on (it's not the
> connection itself, I am on a private LAN and other
> jdbc methods return information immediately).

>
> 6) The md.getTypeInfo() method returns every single
> tablename, sequence etc. as a type. This method should
> only return types like "integer", "timestamp" etc, NOT
> the name of every single table !
As Kris pointed out each table is a class, or type.
>
> 7) There is no way to change the catalog of the JDBC
> connection. What I want is:
>
> myconnection.setCatalog("template1")
> get a connection to the "template1" database
> then say: myconnection.setCatalog("foo")
> get a connection to the "foo" database.

> This does not seem to be possible with the postgres
> driver. Why does the driver not treat a postgres
> database as a "catalog" or least pretend to ? The
> current state of affairs is a serious deficiency.
again Kris addressed this
>
> 8) It would be nice if the driver supported an auto
> reconnect feature. There is no documentation or readme
> file that comes with the compiled driver that talks
> about connection timeautos, auto-reconnecting
> connections etc.

>
> 9) The MD5 documentation is missing and the JDBC
> driver does not work if passwords are used on the
> server. (if we choose password authentication, then
> the latest 7.3 postgres release defaults to MD5 when I
> compile it out of the box). Currently, I've been
> unable to connect using "password" but can only
> connect using "trust".
>
> Best regards,
>
> --j
>
>
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--
Dave Cramer <Dave@micro-automation.net>