V$PQ_SESSTAT lists session statistics for parallel queries. After you have run a query or DML operation, you can use the information derived from V$PQ_SESSTAT to view the number of slave processes used, and other information for the session and system.
Name of the statistic:
Queries Parallelized - Number of queries run in parallel
DDL Parallelized - Number of DDL operations run in parallel
DML Parallelized - Number of DML operations run in parallel
DFO Trees - Number of executed DFO trees
DOP - Degree of parallelism used for the last statement
Server Threads - Number of PX servers used
Allocation Height - Requested number of servers per instance
Allocation Width - Requested number of instances
Local Msgs Sent - Number of local (intra-instance) messages sent
Distr Msgs Sent - Number of remote (inter-instance) messages sent
Local Msgs Recv'd - Number of local (intra-instance) messages received
Distr Msgs Recv'd - Number of remote (inter-instance) messages received
Slave Sets - Total number of slave sets used for the last statement. For multiple parallelizers in the parallel plan, it is the cumulative count.
Value of the statistic for the last operation
Value of the statistic for the entire session to this point in time.
The value of the statistic for the entire session to this point in time is not maintained for the DOP, Server Threads, Allocation Height, Allocation Width, and Slave Set statistics.
The ID of the container to which the data pertains. Possible values include:
0: This value is used for rows containing data that pertain to the entire CDB. This value is also used for rows in non-CDBs.
1: This value is used for rows containing data that pertain to only the root
n: Where n is the applicable container ID for the rows containing data