Re: snapshots

From: Connor McDonald <connor_mcdonald_at_yahoo.com>
Date: Mon, 12 Jul 1999 21:43:21 +0800
Message-ID: <3789F0F9.4472@yahoo.com>

Kasper Kombrink wrote:
>
> Hi I am kinda new to this group, and I have the following question!
> When do you use Snapshots? Why not use views instead? And is there any good
> documentation around how to use Snapshots?
>
> TIA
>
> Kasper
> kombrink_at_dds.nl

Two reasons come to mind immediately:

1. accessing data from a remote oracle database

Say the data you want to read is across a 64k line and you have 300 users wanting to run reports on that data. A view won't help since it still will be dragging the data across the network. A snapshot will have a LOCAL copy of the data avoiding the network bottleneck.

b. summary information

you have a billion row table and you want to get subtotals based on one of the columns. a view will do it but you are still reading a billion rows to do it. a snapshot will have a copy of the summarised data (albeit a slightly out of date one). then (say) every night you refresh this so that people have relatively up to date data without clobbering the server

Cheers
--

---

Connor McDonald
"These views mine, no-one elses etc etc" connor_mcdonald_at_yahoo.com

"Some days you're the pigeon, and some days you're the statue." Received on Mon Jul 12 1999 - 08:43:21 CDT