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spfile timestamp changing every startup?

rjames0705
rjames0705 Member Posts: 1
edited Aug 7, 2019 4:42PM in Social Groups

Hello Everyone!

   I am seeing my spfile's timestamp update every time the database is shutdown and started.

Why this is happening?

Is this intended functionality?

It is 12.1.0.2

Solaris OS.

The spfile parameter is pointing to the correct location.

The pfile is not being specified.

I am not sure what else to check...if I even need to check more into this...

Thank you!

Answers

  • BPeaslandDBA
    BPeaslandDBA Member Posts: 4,615 Blue Diamond
    edited Jul 29, 2019 4:40PM

    Your SPFILE contains your parameter values used for Oracle to configure itself on instance startup. Oracle has the ability to automatically adjust its memory allocations if you are using the MEMORY_TARGET or SGA_TARGET parameter. The current memory allocations in your SGA have been determined by analyzing the workload over the lifetime of that instance. When you shutdown the instance, it would be beneficial if Oracle could know where it left off the next time the instance starts up. For example, your SGA is 10GB and on initial startup, Oracle allocates 5GB of that to the Buffer Cache and 1GB to the Shared Pool. But over its lifetime, Oracle determines life would be better if 4GB were allocated to the Buffer Cache and 1.5 GB to the Shared Pool and the other 0.5 GB got added to the Large Pool, as an example. When you shutdown the instance, Oracle writes those settings to the SPFILE. When Oracle starts up, your parameter says to allocate 10GB to the SGA and then Oracle look at where it left off as a starting point for the SGA components. If you want to see what Oracle writes, do this:

    create pfile='/home/oracle/pfile.txt' from spfile;

    Then open pfile.txt in a text editor. All of those parameters with double underscores at the beginning are examples of what I'm talking about.

    Cheers,

    Brian