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How do I remove all hidden parameters from Oracle Database before upgrading? I'm using the SQL query below. So what do you recommended?

SELECT name,description from SYS.V$PARAMETER WHERE name LIKE '\_%' ESCAPE '\'

Here are parameters:

_fast_full_scan_enabled
_gby_hash_aggregation_enabled
_like_with_bind_as_equality
_optimizer_push_pred_cost_based
_sort_elimination_cost_ratio
_sqlexec_progression_cost
_trace_files_public
_b_tree_bitmap_plans

Regards,

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2 Answers

up vote 2 down vote accepted

Create a pfile from the spfile:

CREATE PFILE FROM SPFILE;

Edit the generated pfile and remove the parameters, then recreate the spfile from the edited pfile. Bounce the database & all should be well.

The database might need to be down when you recreate the spfile from the pfile.

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You'd need to add IS_SPECIFIED (or ISSPECIFIED) to the where clause, as some hidden parameters may be set by... other things.

A parameter can be removed from an spfile by issuing:

ALTER SYSTEM RESET "_some_hidden_parameter" scope = spfile;

You will likely have to stop and start the instance(s) to have the changes take effect.

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Upvote for you. Didn't know about the RESET clause! –  FreshPhilOfSO May 12 '13 at 0:13
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