Q: Why line 0 which is top line of explain plan has actual time lower than intermediate results
Hello all,
I've set statistics_level to all and executed a query, then I found the following actuals that seem to have incorrect values (I omitted some columns to ease visualization):
| 22 | ---------------------------------------------------------------------------------------..------------------------------------------ |
| 23 | | Id | Operation | Name | Starts |..| A-Rows | A-Time | Buffers | Reads | |
| 24 | ---------------------------------------------------------------------------------------..------------------------------------------ |
| 25 | | 0 | SELECT STATEMENT | | 1 |..| 1 |00:08:11.36 | 1483M| 29771 | |
| 26 | | 1 | SORT UNIQUE | | 1 |..| 1 |00:08:11.36 | 1483M| 29771 | |
| 27 | | 2 | UNION-ALL | | 1 |..| 289 |00:08:11.36 | 1483M| 29771 | |
| 28 | | 3 | NESTED LOOPS | | 1 |..| 0 |00:00:06.89 | 91234 | 7546 | |
| 29 | | 4 | NESTED LOOPS | | 1 |..| 0 |00:00:06.89 | 91234 | 7546 | |
| 30 | | 5 | NESTED LOOPS | | 1 |..| 0 |00:00:06.89 | 91234 | 7546 | |
| 31 | | 6 | NESTED LOOPS | | 1 |..| 54795 |00:00:05.56 | 14867 | 6401 | |
| 32 | |* 7 | TABLE ACCESS BY INDEX ROWID | MTL_MATERIAL_TRANSACTIONS | 1 |..| 1 |00:00:00.01 | 4 | 4 | |
| 33 | |* 8 | INDEX UNIQUE SCAN | MTL_MATERIAL_TRANSACTIONS_U1 | 1 |..| 1 |00:00:00.01 | 3 | 3 | |
| 34 | |* 9 | TABLE ACCESS BY INDEX ROWID | MTL_MATERIAL_TRANSACTIONS | 1 |..| 54795 |00:00:05.55 | 14863 | 6397 | |
| 35 | |* 10 | INDEX RANGE SCAN | MTL_MATERIAL_TRANSACTIONS_N1 | 1 |..| 55198 |00:00:00.35 | 269 | 269 | |
| 36 | |* 11 | TABLE ACCESS BY INDEX ROWID | MTL_TXN_REQUEST_HEADERS | 54795 |..| 0 |00:00:01.31 | 76367 | 1145 | |
| 37 | |* 12 | INDEX UNIQUE SCAN | MTL_TXN_REQUEST_HEADERS_U1 | 54795 |..| 13003 |00:00:00.85 | 63364 | 716 | |
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