That is gold! Thanks for lightening up my morning.
Cheers
Tony
On 15 April 2018 5:03:51 am AEST, Mladen Gogala <gogala.mladen@xxxxxxxxx> wrote:
That is, as far as I remember, the 11th commandment on the tablets
handed to Moses on Mt. Sinai:
"Thou shalt always use index range scan"
In the beginning, there was a rule base optimizer, which used a ranked
list of access methods. The optimizer has always selected the access
method with the highest rank. Full table scan was at the bottom of the
list, single row scan by rowid and single row scan by PK were at the
very top of the list. Hash access methods were not on the list. And God
saw that RBO was good simple. But then the devil has created CBO and
made a set of complex rules which change from release to release.
However, it is ordained that faithful should still use RBO principles
and ignore CBO, statistics and all related devil's handiwork.
On 04/14/2018 11:19 AM, Frits Hoogland wrote:
My question would be: why an index range scan MUST be used? What is
the reason for this person to deem it mandatory?
--
Mladen Gogala
Database Consultant
Tel: (347) 321-1217
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