Re: What's the point of decreasing consistent gets by using IOTs?

From: Jonathan Lewis <jonathan_at_jlcomp.demon.co.uk>
Date: Thu, 17 Apr 2003 22:57:17 +0100
Message-ID: <b7n7to$32b$1$830fa78d@news.demon.co.uk>

(a) Because a full tablescan starts with 2 (v9) or 4 (v8 - due to a bug) examinations of the segment header block before it starts scanning the data.

(b) because the CPU cost of checking a
condition on every row in a block could be much higher than the CPU cost of a binary chop through an index block to find a rowid and go to the right row in the table block.

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"NetComrade" <andreyNSPAM_at_bookexchange.net> wrote in message
news:3e9f16a5.212956014_at_nyc.news.speakeasy.net...
> come to think of it.. why does oracle do 2 lookups and not an FTS of
a
> table that has 4 rows and fits in one block?
> .......
> We use Oracle 8.1.7.4 on Solaris 2.7 boxes
> remove NSPAM to email

Received on Thu Apr 17 2003 - 16:57:17 CDT