Gunther Oracle APEX und Datenbank Wiki

Per default dürfen Parallel Queries sich über das ganze Cluster erstecken. So können Parallel Slave Prozesse auf anderen Knoten auftauchen.
Hier tauchen oft dann erhebliche Performance Problem bzgl. der masiven Kommunikation über den Interconnet auf.

Mit Parallel Groups kann diese Verhalten gesteuert werden.
Pro Knoten im Cluster, im Beispiel 3 Stück, wird eine Instance group definiert und die Ausführung von parallelen Slave Prozesen auf diese Gruppe eingeschränkt.

Auszug aus der init.ora:

 GPI1.instance_groups=IGroupGPI1
 GPI1.parallel_instance_group=IGroupGPI1

 GPI2.instance_groups=IGroupGPI2
 GPI2.parallel_instance_group=IGroupGPI2

 GPI3.instance_groups=IGroupGPI3
 GPI3.parallel_instance_group=IGroupGPI3

Script für die Analyse:

col username for a12
col "QC SID" for A6
col "SID" for A6
col "QC/Slave" for A8
col "Req. DOP" for 9999
col "Actual DOP" for 9999
col "Slaveset" for A8
col "Slave INST" for A9
col "QC INST" for A6
 
set pages 300 lines 300
 
col wait_event format a30
 
select
decode(px.qcinst_id,NULL,username, 
' - '||lower(substr(pp.SERVER_NAME,
length(pp.SERVER_NAME)-4,4) ) )"Username",
decode(px.qcinst_id,NULL, 'QC', '(Slave)') "QC/Slave" ,
to_char( px.server_set) "SlaveSet",
to_char(s.sid) "SID",
to_char(px.inst_id) "Slave INST",
decode(sw.state,'WAITING', 'WAIT', 'NOT WAIT' ) as STATE,     
case  sw.state WHEN 'WAITING' THEN substr(sw.event,1,30) ELSE NULL end as wait_event ,
decode(px.qcinst_id, NULL ,to_char(s.sid) ,px.qcsid) "QC SID",
to_char(px.qcinst_id) "QC INST",
px.req_degree "Req. DOP",
px.degree "Actual DOP"
from gv$px_session px,
gv$session s ,
gv$px_process pp,
gv$session_wait sw
where px.sid=s.sid (+)
and px.serial#=s.serial#(+)
and px.inst_id = s.inst_id(+)
and px.sid = pp.sid (+)
and px.serial#=pp.serial#(+)
and sw.sid = s.sid  
and sw.inst_id = s.inst_id   
order by
  decode(px.QCINST_ID,  NULL, px.INST_ID,  px.QCINST_ID),
  px.QCSID,
  decode(px.SERVER_GROUP, NULL, 0, px.SERVER_GROUP), 
  px.SERVER_SET, 
  px.INST_ID
/
 
set pages 300 lines 300
col wait_event format a30
 
select 
  sw.SID as RCVSID,
  decode(pp.server_name, 
         NULL, 'A QC', 
         pp.server_name) as RCVR,
  sw.inst_id as RCVRINST,
case  sw.state WHEN 'WAITING' THEN substr(sw.event,1,30) ELSE NULL end as wait_event ,
  decode(bitand(p1, 65535),
         65535, 'QC', 
         'P'||to_char(bitand(p1, 65535),'fm000')) as SNDR,
  bitand(p1, 16711680) - 65535 as SNDRINST,
  decode(bitand(p1, 65535),
         65535, ps.qcsid,
         (select 
            sid 
          from 
            gv$px_process 
          where 
            server_name = 'P'||to_char(bitand(sw.p1, 65535),'fm000') and
            inst_id = bitand(sw.p1, 16711680) - 65535)
        ) as SNDRSID,
   decode(sw.state,'WAITING', 'WAIT', 'NOT WAIT' ) as STATE     
from 
  gv$session_wait sw,
  gv$px_process pp,
  gv$px_session ps
where
  sw.sid = pp.sid (+) and
  sw.inst_id = pp.inst_id (+) and 
  sw.sid = ps.sid (+) and
  sw.inst_id = ps.inst_id (+) and 
  p1text  = 'sleeptime/senderid' and
  bitand(p1, 268435456) = 268435456
order by
  decode(ps.QCINST_ID,  NULL, ps.INST_ID,  ps.QCINST_ID),
  ps.QCSID,
  decode(ps.SERVER_GROUP, NULL, 0, ps.SERVER_GROUP), 
  ps.SERVER_SET, 
  ps.INST_ID
/
 
set pages 300 lines 300
 
col "Username" for a12
col "QC/Slave" for A8
col "Slaveset" for A8
col "Slave INST" for A9
col "QC SID" for A6
col "QC INST" for A6
col "operation_name" for A30
col "target" for A30
 
select
decode(px.qcinst_id,NULL,username, 
' - '||lower(substr(pp.SERVER_NAME,
length(pp.SERVER_NAME)-4,4) ) )"Username",
decode(px.qcinst_id,NULL, 'QC', '(Slave)') "QC/Slave" ,
to_char( px.server_set) "SlaveSet",
to_char(px.inst_id) "Slave INST",
substr(opname,1,30)  operation_name,
substr(target,1,30) target,
sofar,
totalwork,
units,
start_time,
timestamp,
decode(px.qcinst_id, NULL ,to_char(s.sid) ,px.qcsid) "QC SID",
to_char(px.qcinst_id) "QC INST"
from gv$px_session px,
gv$px_process pp,
gv$session_longops s 
where px.sid=s.sid 
and px.serial#=s.serial#
and px.inst_id = s.inst_id
and px.sid = pp.sid (+)
and px.serial#=pp.serial#(+)
order by
  decode(px.QCINST_ID,  NULL, px.INST_ID,  px.QCINST_ID),
  px.QCSID,
  decode(px.SERVER_GROUP, NULL, 0, px.SERVER_GROUP), 
  px.SERVER_SET, 
  px.INST_ID
/