DSXchange

The 2 input sources have 10 rows each. The output is much greater than 10. I am sorting and hash partitioning on the key column on the input of the join. How can it be?

What does an inner join have to do with how many rows come out? Never heard of a cartesian product? Depends on the nature of the join keys and the data being joined.

Worst case - every row has the same key value. Every row from the left input will therefore match every row from the right output. You'll get 100 rows output.

Yes. If my 2 input links have 100 rows each, the maximum I can get is 100 rows on an inner join, right? I can never get more than 100 but I am getting more. I am joining on the key.

abc123 wrote:Yes. If my 2 input links have 100 rows each, the maximum I can get is 100 rows on an inner join, right? I can never get more than 100 but I am getting more. I am joining on the key.

You still don't get it, do you?

With 100 input rows on each, you can get 100 * 100 = 10,000 rows at the most even with an inner join. This happens when the join happens to do a cartesian product since all the key values in both tables are the same. So, the number of output rows really depends on the keys and values.

another way this can happen is if one of your keys contains nulls - ive seen this before and it produces oodles of output