Re: Index on two columns not used

Hi, Alvaro,

Alvaro Herrera wrote:

>> Additionally, in most UPDATE cases, the new row version will fit into
>> the same page as the old version. In this case, the index does not have
>> to be changed, which is an additional speed improvement.
> Actually, when the UPDATE puts a new row version in the same heap page,
> the index must be updated anyway.

AFAICS only, when the index covers (directly or via function) a column
that's actually changed.

Changing columns the index does not depend on should not need any write
access to that index.

Correct me if I'm wrong.

Thanks,
Markus
--
Markus Schaber | Logical Tracking&Tracing International AG
Dipl. Inf.     | Software Development GIS

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