Subject Re: [Firebird-Architect] Extending execution path information in Vulcan
Author Arno Brinkman

>> Now is my proposal to extend these information items with isc_info_rsb_estimation and under this item the items for
>> cardinality, selectivity and cost.
>> If nobody has objects i'll add this functionality to Vulcan.
>> The next question is how to represent a double (which data structure) in those information items.

> Do you actually need the precision of a double? A simpler alternative
> is to use a number with an implicit denominator, e.g. 200 meaning 200 /
> 10000. If 10,000 isn't fine enough, pick a different implicit denominator.

In that case it would indeed be a simple integer, so that i can use the standard routines.
For Cost 100 would be enough, because this should reflect the number of page fetches. Selectivity otoh can rarely go
above 1 thus should have a high number instead.
Not a very nice solution IMO, but it's way of doing it and easily to handle at all clients.

Arno Brinkman

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