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Buffer busy waits -- p3=1012 and 1016

From: Diego Cutrone <dcutrone_at_afip.gov.ar>
Date: Wed, 25 Apr 2001 11:10:56 -0700
Message-ID: <F001.002F2160.20010425092055@fatcity.com>

Hi list,I'm analyzing parameter "p3" from trace 10046 level 8 and I've got some doubts about it.What is the difference between p3=1012 and p3=1016?According to some docs I've read, 1012="A modification is happening on a XCUR (or SCUR)buffer and it has not yet completed" (and I think thatthe session suffering the wait needs the block inCURRENT mode, thats because it has to wait)1016="The session wants the block in SCUR or XCURmode"(And I think that the session that wants the block hasto wait because the block has been modified by another session)Aren't these two p3 values the same?The only difference seems to be that in the first casethe block is *currently* being modified by anothersession, while in the second case it has already beenmodified.am I right? Please someone correct me if I'm wrong.TIAPD: Some examples below:SOURCE P1,P2,P3               
OWNER     

SEGMENT_NAME                  

SEGMENT_TYPEp1=2 p2=1887
p3=1012           
SYS        
R10                           

Rp1=2 p2=1887
p3=1016           
SYS        
R10                           

Rp1=2 p2=19697
p3=1016          
SYS        
R08                          

Rp1=42 p2=16853
p3=0           
GL       
GL_JE_LINES_N1                 

Ip1=42 p2=22492
p3=0           
GL       
GL_JE_LINES_N1                 

Ip1=43 p2=68119
p3=0           
GL        
GL_JE_LINES                   

TWhat about this P3=0 case ?I think it means that the block wanted by the session. A is being read by another session (say B) from diskto the SGA. So session A has to wait for the read to complete. What can I do to eliminate  (or at least improve) this wait?(may be to cache these table blocks in the
SGA??)thanks Received on Wed Apr 25 2001 - 13:10:56 CDT

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