PGA & Parallelism

Question

Hello,
In dedicated server mode , each dedicate server process has its own PGA area.
For parallel erserver processes, how does this mechanism work?
Dows the coordinator process has this area and the slaves uses the coordinator's PGA or
each slave parallel server process has its own private PGA.
Thanks in advance,

Answer 1

Each PX slave as well as QC has it's own private memory to use for workareas which is used exclusively, though V$SQL_WORKAREA_ACTIVE view may report that some PX slaves uses the very same workarea, for ex.:
select sql_id
      ,workarea_address
      ,operation_type
      ,operation_id
      ,trunc(sum(work_area_size) / 1024 / 1024) "WA Size, MB"
      ,sum(tempseg_size) / 1024 / 1024 "Temp Size, MB"
      ,number_passes
      ,count(*)
  from v$sql_workarea_active
where sid <> (select sid from v$mystat where rownum = 1)
group by sql_id, workarea_address, operation_type, operation_id, number_passes;
SQL_ID        WORKAREA_ADDRESS OPERATION_TYPE                 OPERATION_ID WA Size, MB Temp Size, MB NUMBER_PASSES   COUNT(*)
134yn9m7w133v 000000014FFCED50 HASH-JOIN                                 9        1771           973             0          7
134yn9m7w133v 000000014FFB87E8 HASH-JOIN                                 9         758           417             0          3
134yn9m7w133v 000000014FFC5340 HASH-JOIN                                 9         254           139             0          1
134yn9m7w133v 000000014FFAF0B0 HASH-JOIN                                 9         253           139             0          1This was captured on 10.2.0.3 IIRC.