Parallel Query Tuning - Expert Oracle RAC Performance Diagnostics and Tuning - page 262

GV$PX_PROCESS_SYSSTAT
This view shows the status of query servers and provides buffer allocation statistics:
STATISTIC VALUE
------------------------------ ----------
Servers In Use 0
Servers Available 27
Servers Started 12513
Servers Shutdown 12486
Servers Highwater 264
Servers Cleaned Up 0
Server Sessions 987699
Memory Chunks Allocated 3093
Memory Chunks Freed 3089
Memory Chunks Current 4
Memory Chunks HWM 44
Buffers Allocated 36799839
Buffers Freed 36799812
Buffers Current 27
Buffers HWM 5349
GV$PQ_SESSTAT
This view reflects the status of all current server groups in the system such as data about how queries allocated
processes and how the multiuser and load balancing algorithms are affecting the default and hinted values:
STATISTIC LAST_QUERY SESSION_TOTAL
------------------------------ ---------- -------------
Queries Parallelized 1 2
DML Parallelized 0 0
DDL Parallelized 0 0
DFO Trees 1 2
Server Threads 7 0
Allocation Height 1 0
Allocation Width 7 0
Local Msgs Sent 3 6
Distr Msgs Sent 18 36
Local Msgs Recv'd 3 6
Distr Msgs Recv'd 18 36
GV$PQ_TQSTAT
The view provides a detailed report of message traffic at the table queue level. The data in this view is valid only
when queried from a session that is executing parallel SQL statements. A table queue is the pipeline between query
server groups, between the parallel coordinator and a query server group, or between a query server group and the
coordinator. The table queues are represented explicitly in the operation column by PX SEND and PX RECEIVE .
The view has a row for each query server process that reads from or writes to in each table queue. A table queue
connecting 4 consumer processes to 4 producer processes has 8 rows in this view. Sum the bytes column and group by
TQ_ID to obtain the total number of bytes sent through each table queue.