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Re: [PATCHES] Patch for broken JDBC's getColumn()

From: Barry Lind <barry(at)xythos(dot)com>
To: Jeroen van Vianen <jeroen(dot)van(dot)vianen(at)satama(dot)com>
Cc: pgsql-patches(at)postgresql(dot)org, pgsql-jdbc(at)postgresql(dot)org
Subject: Re: [PATCHES] Patch for broken JDBC's getColumn()
Date: 2001-08-31 01:45:44
Message-ID: 3B8EEC48.7070303@xythos.com (view raw or flat)
Thread:
Lists: pgsql-jdbcpgsql-patches
The java part of this patch looks OK to me.  I don't know the internal 
postgres table structures well enough to have any meaningfull comments 
on the SQL statement.

As for this only supporting 7.1 and higher, that is OK IMHO.  We have 
only really tried beginning with the 7.2 release to maintain full 
backward compatibility.  Thus with 7.2 we should fully support running 
against a 7.1 or 7.2 server, further back than this will work for many 
things, but not everything.

thanks,
--Barry



Jeroen van Vianen wrote:
> Hi,
> 
> Attached is a patch for JDBC's getColumn() function that was broken / 
> flawed in the following ways:
> 
> 1. Only returned columns that had a default value defined, rather than 
> all columns in a table
> 2. Used 2 * N + 1 queries to find out attributes, comments and typenames 
> for N columns.
> 
> By using some outer join syntax it is possible to retrieve all necessary 
> information in just one SQL statement. This means this version is only 
> suitable for PostgreSQL >= 7.1. Don't know whether that's a problem.
> 
> I've tested this function with current sources and 7.1.3 and patched 
> both jdbc1 and jdbc2. I haven't compiled nor tested the jdbc1 version 
> though, as I have no JDK 1.1 available.
> 
> Note the discussion in 
> http://fts.postgresql.org/db/mw/msg.html?mid=1029626 regarding 
> differences in obtaining comments on database object in 7.1 and 7.2. I 
> was unable to use the following syntax (or similar ones):
> 
> select
>     ...,
>     description
> from
>     ...
>     left outer join col_description(a.attrelid, a.attnum) description
> order by
>     c.relname, a.attnum;
> 
> (the error was parse error at or near '(') so I had to paste the actual 
> code for the col_description function into the left outer join. Maybe 
> someone who is more knowledgable about outer joins might provide me with 
> a better SQL statement.
> 
> Please review.
> 
> Regards,
> 
> 
> Jeroen
> 
> 
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