Re: index full scan over an index fast full scan in an analytic function?

Tanel

Tanel Poder wrote:
> As an addition to Vladimir's response:

I cannot provide you with detailed information -- can only give pointers to the documentation -- otherwise it would look suspicious :)

> Full scan will search from index root block using branch blocks to first
> leaf block. And since all leaf blocks have pointers to next and previous
> leaf block in index, sequentially reading only leaf blocks is sufficient for
> returning all values in index, in order (keys are ordered inside leaf blocks
> as well).
>
> FFS will scan from index header block (note that index segment header and
> index root block are different ones) up to segment high water mark using
> multiblock reads and ignoring contents of root, branch, bitmap, extent map,
> freelist group blocks. Rows are returned as they've read from blocks, thus
> no order can be guaranteed.

"Rows are returned as they've read from blocks, thus no order can be guaranteed."

Not rows, but blocks returned as is in order they being read. Keys (rows) are ordered inside leaf blocks -- as you wrote above. So, inside the blocks the order is consistent but blocks are 'mixed' whilst read.

Things (parameters etc.) are changing, as Cary pointed out, principles are not.

-- 
Vladimir Begun
The statements and opinions expressed here are my own and
do not necessarily represent those of Oracle Corporation.

-- 
Please see the official ORACLE-L FAQ: http://www.orafaq.net
-- 
Author: Vladimir Begun
  INET: Vladimir.Begun_at_oracle.com

Fat City Network Services    -- 858-538-5051 http://www.fatcity.com
San Diego, California        -- Mailing list and web hosting services
---------------------------------------------------------------------
To REMOVE yourself from this mailing list, send an E-Mail message
to: ListGuru_at_fatcity.com (note EXACT spelling of 'ListGuru') and in
the message BODY, include a line containing: UNSUB ORACLE-L
(or the name of mailing list you want to be removed from).  You may
also send the HELP command for other information (like subscribing).