That is exactly the point, Kevin, I read the documentation and found out
that "amgettuple" and "amgetbitmap" are optional. I just wondered if
there is more information about this topic?
Additionally, I can not find "amcostestimate" in hash.h or anywhere, or
am I missing something? So "All of them" lacks some exceptions, or?
Am 22.04.2011 17:27, schrieb Kevin Grittner:
> Leonardo Francalanci <m_lists@yahoo.it> wrote:
>>>> another question regarding indexes. Sadly I can't find enough
>>>> info in the documentation. Which of the functions are needed in
>>>> order for a index to work?
>>>
>>> All of them.
>>
>>
>> Maybe I completely misunderstood the question, but some functions
>> are "optionals", such as amgetbitmap, right?
>>
>> http://www.postgresql.org/docs/9.0/static/index-functions.html
>
> Browsing that page, I think these are the two relevant bits
> regarding exceptions to the rule:
>
> | The amgettuple function need only be provided if the access method
> | supports "plain" index scans. If it doesn't, the amgettuple field
> | in its pg_am row must be set to zero.
>
> | The amgetbitmap function need only be provided if the access
> | method supports "bitmap" index scans. If it doesn't, the
> | amgetbitmap field in its pg_am row must be set to zero.
>
> I have no idea which of these would be useful for the AM being
> discussed.
>
> -Kevin
>