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Thread: SGA Size

  1. #1
    Join Date
    Aug 2002
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    2
    Is there a formula for properly sizing your SGA for each database instance?

  2. #2
    Join Date
    Oct 2001
    Location
    Madrid, Spain
    Posts
    763
    Yes. Your application has the magic formula about how your DB could be

    Cheers

    Angel

  3. #3
    Join Date
    Aug 2002
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    2
    actually it doesn't. I've been getting ora-4031 errors lately. no one in development seems to know what to set the shared pool to or the SGA..................

  4. #4
    Join Date
    Nov 2000
    Location
    Pittsburgh, PA
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    4,166
    There are numerous bugs in Oracle 8.1.7 and 9i relating to this error. You should do research to find out if you particular situation is really a bug. however, If your server has at least 256MB RAM and one SID your total SGA should be 60-80% of total physical RAM. A minimum Shared_Pool of 60M and Block buffers of 20-80MB depending on how many stored procs, functions, packages etc and how much data your database actually has. There are many queries on this site that will give you cache hits which will give you a general idea about SGA sizing. Check the Alert Log and post the entry for your error and maybe someone will point out which specific bug you might be encountering, if it is really a bug that is causing the problem.

  5. #5
    Join Date
    Jun 2001
    Location
    Helsinki. Finland
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    3,938
    Originally posted by dbman
    actually it doesn't. I've been getting ora-4031 errors lately. no one in development seems to know what to set the shared pool to or the SGA..................
    Poor init.ora is the probelm. If you need help, please post it here.
    Oracle Certified Master
    Oracle Certified Professional 6i,8i,9i,10g,11g,12c
    email: ocp_9i@yahoo.com

  6. #6
    Join Date
    Jan 2000
    Location
    Chester, England.
    Posts
    818
    I have had no SGA errors when using 8.1.5 even though the DBs were generally created with default init.ora params for sizings (created using Configuration Assistant)

    However, I recently created our first 8.1.7 DB. It's used by 1 developer writing a fairly small system and we've had ORA-04031 errors.

    I just doubled the SHARED_POOL_SIZE init.ora param and we've had no problems since.

    My problem is that as he's still developing we have no real idea of how big the system will eventually be - and no real idea of volumes etc. We're not even sure how powerful the server will be - hence my rather bombastic solution.

    If anyone knows of some good resources for estimating SGA sizes based on different scenarios then I'd love to read them.

    Keep up the good work chaps.

    JMac

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