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Below is the explain plan I can't wrap my mind around.

On a high level it seems it is updating the Lineitem table through the OrderLine join index (not at all sure about this), and it is executing this in parallel,

Explanation

1) First, we execute the following steps in parallel.
1) We do a single-AMP UPDATE from join index table AMT4.OrderLine by way of the primary index "AMT4.OrderLine.l_orderkey = 10" with a residual condition of ("AMT4.OrderLine.l_orderkey = 10").

2) We do a single-AMP UPDATE from AMT4.Lineitem by way of the primary index "AMT4.Lineitem.l_orderkey = 10" with no residual conditions.

Appreciate someone helping me understand this.

user3055262
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1 Answers1

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This is an UPDATE on AMT4.Lineitem with a WHERE-condition on the table's Primary Index.

And there's a Join Index (AMT4.OrderLine) on that table, which is automatically maintained during the update. The JI got the same PI as the base table and is also updated via it's Primary Index.

dnoeth
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