Re: USE_MERGE hint and the correct way to hint
- From: Nigel Thomas <nigel_cl_thomas@xxxxxxxxx>
- To: contactarul@xxxxxxxxx, oracle-l <oracle-l@xxxxxxxxxxxxx>
- Date: Wed, 7 Feb 2007 12:29:38 -0800 (PST)
>I played around with changing the order of the tables
>in the FROM clause and in the use_merge hint. It does
>change the order in the plan, but the logical reads come
>to the same.
Arul
A merge join is like a zipper - you take two (sorted) rowsets and read through
both of them concurrently. So (in principle, in a simple case) there's no
difference between merge-joining A to B or merge joining B to A;
I'm intrigued that there's no table access to CUS_ACC. Does that contain only
the ACC_ID column, whose value we can derive from the PK_CUS_ACC index? Or is
it index-organised?
Nigel
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