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Re: Difference in JDBC re

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  To: comp.lang.java.databases
Tom Cole wrote:
> On Sep 12, 7:54 am, Martin Gregorie
> <mar...@see.sig.for.address.invalid> wrote:
>> On Thu, 11 Sep 2008 15:50:27 -0700, Tom Cole wrote:
>>> On Sep 11, 6:45 pm, Tom Cole <tco...@gmail.com> wrote:
>>>> We're using jTDS to connect to a backend SQL Server 2000 instance. The
>>>> connection is working fine.
>>>> What we want to do is write a utility that will calculate maximum row
>>>> size for each table in a given database. The script we're using looks
>>>> something like this:
>>>> Any ideas what I'm doing wrong here?
>> It looks to me as if your code is calculating the amount of space needed
>> hold the data in a row but is ignoring overheads introduced by the DBMS
>> such as padding between columns, index structures, length indication for
>> a variable length column, etc.
>>
>> As the overheads are implementation specific its probably not possible to
>> calculate them using information returned by JDBC and almost certainly
>> impossible to write a general solution. If the information can be
>> retrieved at all it is likely to be in system tables which vary wildly in
>> number, content and name between database implementations.
>>
>> --
>> martin@   | Martin Gregorie
>> gregorie. | Essex, UK
>> org       |
> 
> Yeah and the bigger problem I will have is that this will be deployed
> on SQL and Oracle installations which also differ wildly.
> Unfortunately I just don't know how to go about estimating how much a
> new row will cost me in a table.

Why on earth would you want to try to estimate that?

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Difference in JDBC result "Tom Cole" <tom.cole@THRWHITE.remove-dii-this> - 2011-04-27 15:22 +0000
  Re: Difference in JDBC re "Martin Gregorie" <martin.gregorie@THRWHITE.remove-dii-this> - 2011-04-27 15:22 +0000
    Re: Difference in JDBC re "Tom Cole" <tom.cole@THRWHITE.remove-dii-this> - 2011-04-27 15:22 +0000
      Re: Difference in JDBC re "Silvio Bierman" <silvio.bierman@THRWHITE.remove-dii-this> - 2011-04-27 15:22 +0000
        Re: Difference in JDBC re "Tom Cole" <tom.cole@THRWHITE.remove-dii-this> - 2011-04-27 15:22 +0000
  Re: Difference in JDBC re "Martin Gregorie" <martin.gregorie@THRWHITE.remove-dii-this> - 2011-04-27 15:22 +0000

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