Re: Predicting Growth.

Ben wrote:
> Ent Ed. 9.2.0.5, DMT's on AIX5L
>
> There isn't really an accurate way to estimate growth of a database, is
> there? I have a history of six months of my data file sizes, but even
> with that there are too many variables envolved to determine that my
> database is going to continue to grow at a rate of 50 gig per year.
>

You've added 25 gig of space in the last six months; how much of that has actually been consumed? You don't state that figure, and I doubt you've taken the time to investigate it.

> Even if you assume a constant rate of growth, how would you base your
> projection?

On how much of that space is actually used. Funny that you don't have that information handy.

>
> For example, lets say my datafiles grew 25G over the last six months.

So? Have you used all of that added space?

> At the beginning of that six months my database was 100G that is 25%
> growth over the past six months.

No, it's a 25% increase in available space.

> Now looking ahead for a year. My database is now 125G, 25% of that is
> 31.25G. Then six months down the road the database will be 156.25G, 25%
> of that is 39.06G, etc etc. But that original 25% figure was calculated
> from the 100G incarnation of the database. So that won't work.

What won't 'work' is your assumption that the overall datafile space somehow translates to actual data growth when, in fact, you have no information to prove that.

> Do I then assume that my database will grow at a constant size instead
> of %? So my 125G db will be 175G by this time next year.

Only if you continue adding 25 gig allocations to it, whether or not you need them. You need to determine how much of that space is actually used, how much of that space is still available, and how long it will take to actually consume that space based upon actual table growth.

> This seems
> more accurate, but I still think there are just too many unknowns to
> actually come to an accurate answer.

They're unknown to YOU because you haven't done the necessary work to determine the actual growth of the data. I suggest you write some queries against dba_free_space, dba_segments and a few other data dictionary views/tables to report on the space actually occupied by data and track the available free space. Simply measuring datafile size does you absolutely no good except to show you how close your are to having a full file system.

David Fitzjarrell Received on Wed Sep 20 2006 - 13:56:29 CDT