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Re: Difference in JDBC re

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  To: comp.lang.java.databases
On Sep 12, 6:55 pm, Silvio Bierman <sbier...@jambo-software.com>
wrote:
> 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?- Hide quoted text -
>
> - Show quoted text -

When deploying an application on a client's system, they want to know
(within bounds) how much disk space/resources they will need in the
future to support an application's database. The goal is to provide
them with a worst case scenario (i.e. maximum row size for all tables
affected) for each new record. Then they would do an analysis to
determine how many new rows they would expect in a week/month/year/
decade, apply that to the formula and get at least some form of
educated guess how big these tables will be in the future.

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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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