Re: sort without order by

From: Jonathan Lewis <jonathan_at_jlcomp.demon.co.uk>
Date: Fri, 19 Nov 1999 20:20:38 -0000
Message-ID: <943043221.3035.2.nnrp-14.9e984b29@news.demon.co.uk>

Fast Full Scan does not run along the leaves and return data in order. It scans the segment using a multi-block read count, and therefore can return leaf and branch blocks in a 'random' order.

Branch blocks are discarded, leaf blocks are reported in the order they are read.

A (?Slow?) Full Index Scan of an index follows the linked list from leaf to leaf, one block at a time and returns the data in index order.

Jonathan Lewis
Yet another Oracle-related web site: http://www.jlcomp.demon.co.uk

Joerg Lanzinger wrote in message <383510A2.56E3FDAC_at_lanzinger.de>...
> . In 8i performing a FFS (fast full scan) will run along
the
>leafs of the index-implementing B-tree, which means ordered output.
>
Received on Fri Nov 19 1999 - 14:20:38 CST