[JDBC] TypeInfoCache

From: Jan de Visser <jdevisser(at)digitalfairway.com>
Date: Wed Dec 19 2007 - 20:39:29 EST

On 12/19/07, Tom Lane <tgl@sss.pgh.pa.us> wrote:
> Oliver Jowett <oliver@opencloud.com> writes:
> > Daniel Migowski wrote:
> >> I think a VARCHAR(50) and text are not interchangeable.
>
> > But a "varchar" (with no limit) and "text" *are* interchangeable, which
> > is why we identify text as VARCHAR
>
> But note that varchar-with-no-limit is itself a Postgres-ism: it's
> not allowed by the standard.

I was about to write the same thing. For educational value, this is what a popular closed-source dbms will tell you:

SQL> create table a ( a varchar );
 create table a ( a varchar )

                            *

ERROR at line 1:
xxx-00906: missing left parenthesis

SQL> create table a (a varchar(4001));
create table a (a varchar(4001))

                          *

ERROR at line 1:
xxx-00910: specified length too long for its datatype

SQL> create table a (a varchar(4000));

Table created.

That's right, textual data longer than 4000 characters needs to go through the CLOB interface. And my license doesn't permit me to say what that does to performance :)

So what Daniel is trying to say here is that Crystal Report probably croaks on a column for the type is Types.VARCHAR but which does not have a maximum length associated with it.

I think his patch is good.

jan

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Received on Wed Dec 19 20:41:13 2007