good evening;

> On 2. Apr 2024, at 12:27, Lorenz Buehmann 
> <[email protected]> wrote:

if this description is accurate

> according to the hash join implementation in Jena in class 
> AbstractIterHashJoin a join key is created via line
>     joinKey = JoinKey.createVarKey(varsLeft, varsRight) ;
> That method does take only the first variable in both bindings as join key 
> instead of all matching variables. In our case that would probably be ?wafer 
> I guess?

and the estimate of constituent cardinality is correct,

>  The cardinality on the left and right side of the join is around 125k.

then, depending on the distribution of the ?wafer values, this could produce a 
large intermediate cross-join.

what is the cardinality of the results prior to the distinct operation?

---
james anderson | [email protected] | https://dydra.com


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