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Posted by Robert Klemme on 10/25/28 11:30
Erland Sommarskog wrote:
> Robert Klemme (bob.news@gmx.net) writes:
>> Erland Sommarskog wrote:
>>> (gilles27@talk21.com) writes:
>>>> Our review of the primary keys was triggered by one of our
>>>> customers complaining about the performance of the database. They
>>>> claimed to have "re-sequenced the primary key which reduced Index
>>>> reads by a factor of 5". Do you have any idea as to how they
>>>> arrived at this conclusion?
>>>
>>> Sounds like hogwash to me.
>>
>> I don't know the table structure and queries but there actually are
>> scenarios with different queries against the same table where the
>> overall benefit of reordering columns is significant.
>
> Of course there is. The main recommendation of this thread is that
> the PK of the table in question should be reordered. The "normal"
> order is (Ledger, OrderNumber, OrderLineNumber), and this was, I
> assume, the original order. What I referred to as hogwash was the
> claim that reordering the index so that OrderLineNumber and
> OrderNumber changed places reduced index reads by a factor 5.
Ah, ok. Thanks for clarification!
robert
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