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Hi,


The question is regarding (Remote Diagnostics Assistant; Metalink Note: 314422.1) Oracle Support provides to troubleshoot performance issues in a database {RDA} and the calculation of the "Top SQL Report"


More specifically, I am curious how the following ratios are deemed "Expected Respose Time (in Seconds)"


From v$sqlarea:
{ (disk_reads/executions)/50 }
{ (buffer_gets/executions)/500 }


Also, what is the significance of the numbers 50 and 500 respectively?


Queries used in the report:


select
sql_text,
executions,
disk_reads / decode(executions,0,1, executions) / 50
from
v$sqlarea
where
disk_reads / decode(executions,0,1, executions) / 50 > 100
order by executions desc;

select
sql_text,
executions,
buffer_gets / decode(executions,0,1, executions) / 500
from
v$sqlarea
where
buffer_gets/ decode(executions,0,1, executions) / 500 > 100
order by executions desc;


Thanks,
Sri

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  • Oracle-l-bounce_at_freelists.org at Mar 1, 2006 at 11:35 pm
    Hmm...interesting...I've never looked at this report......my guess would
    be that they are speculating that a disk read takes about 20 ms, so,
    disk_reads/50 would give you seconds. Same idea for buffer_gets. If a
    buffer get takes 2 ms, then buffer_gets/500 will yield seconds.

    As to how accurate that conversion is, well, that depends on way too
    much stuff to speculate on.....

    -Mark

    --
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    Senior Oracle Architect
    ProQuest Information & Learning

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    -----Original Message-----
    From: oracle-l-bounce_at_freelists.org
    On Behalf Of Srikanth Kalluri
    Sent: Wednesday, March 01, 2006 6:11 PM
    To: Oracle-L Freelists
    Subject: RDA - Top SQL report

    Hi,


    The question is regarding (Remote Diagnostics Assistant; Metalink Note:
    314422.1) Oracle Support provides to troubleshoot performance issues in
    a database {RDA} and the calculation of the "Top SQL Report"


    More specifically, I am curious how the following ratios are deemed
    "Expected Respose Time (in Seconds)"


    From v$sqlarea:
    { (disk_reads/executions)/50 }
    { (buffer_gets/executions)/500 }


    Also, what is the significance of the numbers 50 and 500 respectively?


    Queries used in the report:


    select
    sql_text,
    executions,
    disk_reads / decode(executions,0,1, executions) / 50 from v$sqlarea
    where disk_reads / decode(executions,0,1, executions) / 50 > 100 order
    by executions desc;

    select
    sql_text,
    executions,
    buffer_gets / decode(executions,0,1, executions) / 500 from v$sqlarea
    where buffer_gets/ decode(executions,0,1, executions) / 500 > 100 order
    by executions desc;


    Thanks,
    Sri



    --
    http://www.freelists.org/webpage/oracle-l

    --
    http://www.freelists.org/webpage/oracle-l

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