Re: Database performance and size
Date: 1996/01/03
Message-ID: <4cca8l$oid_at_widow.nla.gov.au>#1/1
>
> Re: Database performance and size
...snip...
>
> The performance will get slower if the number of rows gets bigger!!
> For select-statements:
> - Full table scan's have to read more rows from disk or SGA. (Linear
> slow down)
> - Indexed queries work with search algorithems. a select on a table
> with 100
> rows will be about twice as slow as a select on a table with 10000
> rows.
> (logaritmic slow down)
The main reason for the index slowdown is the depth of the b-tree index structure that must be traversed to find the index entries required to satisfy your query. As the number of rows increases the b-tree structure gets larger as well.
This can be alleviated to some extent by moving to larger block sizes as Oracle has done in their 64bit version where I believe they can have blocks of 64K instead of the current general maximum of 8K. Received on Wed Jan 03 1996 - 00:00:00 CET