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          subject         part



Read the following execution plan , give SQL Execution order of .

 1-----------------------------------------
 2| Id  | Operation
 3-----------------------------------------
 4|   0 | SELECT STATEMENT
 5|   1 |  SORT AGGREGATE
 6|   2 |   VIEW
 7|   3 |    UNION-ALL
 8|*  4 |     FILTER
 9|*  5 |      HASH JOIN
10|   6 |       TABLE ACCESS FULL
11|*  7 |       TABLE ACCESS FULL
12|*  8 |      TABLE ACCESS BY INDEX ROWID
13|*  9 |       INDEX UNIQUE SCAN
14|  10 |     NESTED LOOPS
15|  11 |      INDEX FULL SCAN
16|  12 |      TABLE ACCESS CLUSTER
17|* 13 |       INDEX UNIQUE SCAN
18-------------------------------------------
   




     
          Answer section          



analysis : Using the principle of the most right, the most top and the first execution to see the hierarchical relationship , At the same level, if an action has no children ID, Then we'll do it first , First ,6、7、9、13 The most right , therefore ,6,7 Do it first HASH JOIN, by 6,7,5.

second ,8 Has child nodes , Next is 9,8.

Third ,HASH The result and 8 What are the results FILTER Filter .

Fourth ,10 This node is based on the principle that 11,13,12,10.

The fifth , The rest, in turn, are 3,2,1,0.

therefore , The execution order of the graph is 6,7,5,9,8,4,11,13,12,10,3,2,1,0.