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Conference vmszoo::rms_openvms

Title:RMS asks, 'R U Journaled?'
Moderator:STAR::TSPEERUVEL
Created:Tue Mar 11 1986
Last Modified:Wed Jun 04 1997
Last Successful Update:Fri Jun 06 1997
Number of topics:3031
Total number of notes:12302

2935.0. "How bucket size affect locking and performance ?" by GIDDAY::SHCHIU () Thu May 02 1996 21:54

T.RTitleUserPersonal
Name
DateLines
2935.1EPS::VANDENHEUVELDon't fix it,if it ain't baroqueFri May 03 1996 09:3133
2935.2COOKIE::FROEHLINLet's RAID the Internet!Fri May 03 1996 11:249
2935.3many thanks.GIDDAY::SHCHIUMon May 06 1996 20:3311
2935.4your 2 cents of adviceHANDVC::STEVELIUWed May 07 1997 07:2616
    
    Hein,
    
    it seems that the most direct way to reduce locking and enhance
    performance for a file application is to tune :
    
    o bucket' size and number
    o global buffer
    o local buffer
    
    as you suggested, so what's your checklist when you deal with such
    problem ? yes, your approach. what will do first and then next etc. ?
    
    steve
    
    
2935.5EPS::VANDENHEUVELHeinThu May 08 1997 01:4225
 >   it seems that the most direct way to reduce locking and enhance
 >   performance for a file application is to tune :
 >   
 >   o bucket' size and number
 >   o global buffer
 >   o local buffer
    
    Right, if you can not touch the code. The absolute biggest impact can 
    normally be made by coming up with a better application algoritme.
    
 >   as you suggested, so what's your checklist when you deal with such
 >   problem ? yes, your approach. what will do first and then next etc. ?
    
    You _have_ to understand the applications dominant access patterns.
    If it truly is a sequential scan by primary key, then only bigger
    buckets will help. Buffers will not help in that case. In fact, I would
    even consider explicitly clearing FAB$W_GBC after SYS$OPEN, before 
    the SYS$CONNECT to avoid gloabl buffers if they are there for such
    special sequential scan case [ and only for the seq read application].
    
    Cheers,
    	hein.