Double Underscore Sign In Parameters....

From: Aman Sharma <>
Date: Thu, 9 Oct 2008 19:57:08 -0700 (PDT)
Message-ID: <>

Hi there,
DB: 11106
OS: Win Xp Proff
I understand that with the underscore prefixed , the parameters are called undocumented parameters. But I am seeing at times, parameters having 2 undrescores attached to it too. What's these parameters and why we have two underscores attached to them? For example,
SQL&gt; select ksppinm,ksppstvl,ksppstdvl   2 from x$ksppcv a,x$ksppi b
  3 where a.indx=b.indx and b.ksppinm like '%shared_io%';

KSPPINM                        KSPPSTVL

------------------------------ ------------------------------

__shared_io_pool_size 4194304 4M
_shared_io_pool_size 4194304 4M
_shared_iop_max_size 536870912 512M
_shared_io_pool_buf_size 1048576 1M
_shared_io_pool_debug_trc 0 0
_shared_io_set_value FALSE FALSE

6 rows selected.
You can see that the first one is having a double underscore attached. Similarly, in PGA also , there is __pga_aggregate_target parameter. If anyone can explain this, it would be really great. Thanks
Aman.... Received on Thu Oct 09 2008 - 21:57:08 CDT

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