Re: Pinning Packages

From: Thomas Kyte <tkyte_at_us.oracle.com>
Date: 1998/03/13
Message-ID: <35095498.5480180@192.86.155.100>#1/1

A copy of this was sent to "Joe Babaloo" <jsuriol_at_dsams.com> (if that email address didn't require changing) On Thu, 12 Mar 1998 10:37:44 -0500, you wrote:

>What does Oracle do to memory when it pins packages. Are the memory
>pages in which
>packages reside locked so they cannot be swapped out? What system calls
>does oracle use pin
>those packages?
>
>

It pins the package in the SGA so that Oracle won't swap them out of the SGA. It does not pin the memory at the OS level. Its predominantly used to avoid heap fragmentation caused by paging large pl/sql routines in and out of the SGA.

From the spec of the dbms_shared_pool package:

  procedure keep(name varchar2, flag char DEFAULT 'P');

• Keep an object in the shared pool. Once an object has been keeped in
• the shared pool, it is not subject to aging out of the pool. This
• may be useful for certain semi-frequently used large objects since
• when large objects are brought into the shared pool, a larger
• number of other objects (much more than the size of the object
• being brought in, may need to be aged out in order to create a
• contiguous area large enough.

Thomas Kyte
tkyte_at_us.oracle.com
Oracle Government
Herndon VA  

http://govt.us.oracle.com/ -- downloadable utilities  

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Opinions are mine and do not necessarily reflect those of Oracle Corporation  

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