Re: Number of Columns in a Table & SQL Performance ?

Why? It sounds like you/they are trying to solve something. What is it?

On Mon, Mar 9, 2009 at 9:12 PM, Stephane Faroult <sfaroult_at_roughsea.com>wrote:

> Vivek,
>
> 200 columns look to me like too much - much too much. I'll revise
> design first. If you have many null columns, consider some type of
> inheritance. Even in a complex application, it's extremely rare that you
> manage this number of attributes for all items under management. Get
> your inspiration from the Oracle data dictionary (sys.obj$ that holds
> type, name, owner, etc. for all possible objects and then one table per
> object type that only stores what is relevant to this particular type).
> Index issues are obvious for inserts and deletes, and updates to a
> lesser extent, because I still have to see a super-wide table that
> hasn't a crazy number of indexes; and even if you are careful it's
> likely that someone someday will not be. But think also that you will
> get a very low data density in your blocks (few rows per block), which
> means that any scan will be extremely costly in terms of number of
> blocks read (whether they are read in memory or from the disks). I'll
> avoid mentioning row migration if you ever need to partition your table.
>
> HTH
>
> S Faroult
>
> VIVEK_SHARMA wrote:
> >
> > Folks
> >
> >
> >
> > Does the *number of columns in a table* affect the performance of
> > SELECT/INSERT/UPDATE in *OLTP* Transactions.
> >
> > If so, why?
> >
> >
> >
> > NOTE - Merge of 2 existing tables each has 200 columns approx into a
> > single Table is being planned..
> >
> >
> >
> > Thanks in Advance
> >
> >
> >
> > Vivek
> >
>
>
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>
>
>

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