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From: "Patrick Meyer" <meyerjp3@gmail.com>
To: "'Derby Discussion'" <derby-user@db.apache.org>
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Subject: RE: limit on the number of columns
Date: Fri, 25 May 2012 08:04:26 -0400
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It's hard to say. For my application, the end-user creates the tables. Most
users are fine with the 1,012 limit but some "power" users will have
extremely large datasets. I imagine that a few thousand would be fine.

In looking through documentation of other database systems it looks like
MySQL allows for 2,599 columns. MS SQL Server allows 1,024 for a non-wide
table and 30,000 for a wide table.

Thanks,
Patrick


-----Original Message-----
From: Kristian Waagan [mailto:kristian.waagan@oracle.com] 
Sent: Friday, May 25, 2012 4:21 AM
To: derby-user@db.apache.org
Subject: Re: limit on the number of columns

On 24.05.2012 23:33, Patrick Meyer wrote:
> That would be excellent! I think it would be a great feature to have 
> in Derby.

Hi Patrick,

Can you say anything about how many columns would be needed to support these
use-cases?
Are we talking about a few thousand, ten thousand, or even more columns?


Regards,
-- 
Kristian

>
> Patrick
>
> -----Original Message-----
> From: Rick Hillegas [mailto:rick.hillegas@oracle.com]
> Sent: Thursday, May 24, 2012 12:08 PM
> To: derby-user@db.apache.org
> Subject: Re: limit on the number of columns
>
> On 5/24/12 4:26 AM, Patrick Meyer wrote:
>> I am aware that Derby has a limit of 1,012 columns for each table, but
>> many users of my application (it is a program for statistical
>> analysis) have very large files that go well beyond this number of
>> columns. Does anyone know of a strategy for using multiple tables to
>> present one large "virtual" table to end users? Is there a way to
>> chain tables together to have an endless number of columns? Is this
>> something that can be done through SQL statements? Any advice,
>> examples or documentation on such a strategy would be greatly
>> appreciated.
>>
>> Thanks,
>>
>> Patrick
>>
> Hi Patrick,
>
> This appears to me to be an arbitrary limit in Derby, one which we could
> investigate lifting. To track this issue, I have filed
> https://issues.apache.org/jira/browse/DERBY-5781. This kind of change
would
> have to appear in a feature release. The 1012 limit also applies to the
> number of columns in a SELECT list. This is another arbitrary limit which
we
> should consider lifting:
> https://issues.apache.org/jira/browse/DERBY-5782
>
> Thanks,
> -Rick
>