ALTER SESSION DISABLE PARALLEL QUERY But Query Still Running In Parallel (Doc ID 2218722.1)

Last updated on JANUARY 18, 2017

Applies to:

Oracle Database - Enterprise Edition - Version 12.1.0.2 and later
Information in this document applies to any platform.

Symptoms

 You have disabled parallel query, yet parts of the statement runs in parallel;

SQL> ALTER SESSION DISABLE PARALLEL QUERY;

Session altered.

SQL> SHOW PDBS


CON_ID CON_NAME OPEN MODE RESTRICTED
---------- ------------------------------ ---------- ----------
3 PARISQ READ WRITE NO


 EXPLAIN PLAN FOR
Select '',
 t.Owner,
t.Table_Name,
 To_Number(Null),
 '',
 '',
0,
To_Number(Null),
'',
 '',
 Num_Rows,

...

..

UNION-ALL | | | | | | | | | | | |
|*110 | FILTER | | | | | | | | | | | |
| 111 | PX COORDINATOR | | | | | | | | | | | |
| 112 | PX SEND QC (RANDOM) | :TQ20000 | 2 | 686 | | 1 (100)| 00:00:01 | | | Q2,00 | P->S | QC (RAND) |
| 113 | PX PARTITION LIST ALL | | 2 | 686 | | 1 (100)| 00:00:01 | 1 | 2 | Q2,00 | PCWC | |
|*114 | FIXED TABLE FULL | X$COMVW$ | 2 | 686 | | 1 (100)| 00:00:01 | | | Q2,00 | PCWP | |

Changes

 You upgraded to 12C

Cause

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