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Re: getTables or code problem?

From: Kris Jurka <books(at)ejurka(dot)com>
To: Alessandro Depase <alessandro(dot)depase(at)libero(dot)it>
Cc: <pgsql-jdbc(at)postgresql(dot)org>
Subject: Re: getTables or code problem?
Date: 2004-01-16 20:27:46
Message-ID: Pine.LNX.4.33.0401161507480.16498-100000@leary.csoft.net (view raw or flat)
Thread:
Lists: pgsql-jdbc

On Fri, 16 Jan 2004, Alessandro Depase wrote:

> Hi all,
> I have a problem with the use of DatabaseMetaData.getTables.
> This is the part of code I last tried:
>
> DatabaseMetaData conMD = connection.getMetaData();
> System.out.println("Driver Name:\t" + conMD.getDriverName());
> System.out.println("Driver Version:\t" + conMD.getDriverVersion());
> String[] tableType = {"TABLE"};
> ResultSet tables = conMD.getTables("db2","public",null,tableType); //I tried
> also "%" instead of null, with the same results and "", but founding nothing
> for (int j = 1; j <= tables.getMetaData().getColumnCount(); j++) {
>     System.out.print(tables.getMetaData().getColumnName(j) + "\t");
> }
> System.out.println();
> while (tables.next()) {
>     for (int j = 1; j <= tables.getMetaData().getColumnCount(); j++)
>     {
>         System.out.print(tables.getObject(j) + "\t");
>     }
>     System.out.println();
> }
>
> The result of the first 2 lines is interesting for you, I imagine:
> Driver Name: PostgreSQL Native Driver
> Driver Version: PostgreSQL 7.4 JDBC3 with SSL (build 209)
>
> What is the problem? The list I see as output is the list of the catalog db1
> (the one I connected to using the connection string:
> jdbc:postgresql://myhost:5432/db1 - the schema is "public" in both cases).
>
> Well, this can even sound good to me, but why can I see all the catalogs
> using a
> ResultSet catalogs = conMD.getCatalogs();
> ?

The way the postgresql server works is that you can only connect to one
database at a time.  This means that is impossible to list the tables in a
database that you are not connected to.  The thing is that you can get a
list of all the databases from any database because pg_database is a
global table.  It has been debated here before whether we should return
only the database you are connected to in the results of getCatalogs().
Another option would be to put in a check on a call like getTables to see
if a catalog was passed in that is different from the connected catalog
and either throw an Exception or return no results.

What would make the most sense to you given the server's current
restrictions?

Kris Jurka


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Subject: Re: getTables or code problem?
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