Re: Significance of specific database parameter difference

These 4 I'm familiar with. Comments in-line

nls_sort = 'BINARY' --- important for some application functionality. Could very well be needed in new Database

optimizer_dynamic_sampling=0 --- if you were burning a lot of excess CPU, this will help prevent that. Dynamic sampling can be expensive. If you're not pushing your CPU capacity, then I'd probably leave this at the default (2) instead of 0.

• these two should be default, but you really need to test the application to see if it misbehaves because these can definitely affect the performance of the queries
• I hate when I see these two params set as its a carryover from a long, long time ago but can definitely affect application performance

> Hello All, we are moving from HP to Exadata - X8. Along with this we are
> also moving from current Oracle version 11.2.0.4 to 19C. And below are a
> few of the differences in parameters we see between old and new databases.
> New database(which is not yet live) holds mostly default setup only. But
> the existing database has below non default setup(Around ~12 parameters),
> And I don't know if those non default setups in the old/existing database
> is really helping us anyway. So wanted to understand if it's safe to go by
> all the defaults(as it's mentioned below) for the new database? Or any of
> these non default parameters from existing databases is really critical to
> be double checked/verified thoroughly, so that we may need to move those as
> it is to the new database?
>
>
> *Existing environment (11.2, HP):- *
>
> _buffered_publisher_flow_control_threshold = 500000
>
> _capture_publisher_flow_control_threshold =500000
>
> _enable_query_rewrite_on_remote_objs = true
>
> _optimizer_cost_based_transformation = linear
>
> nls_sort = 'BINARY'
>
> optimizer_dynamic_sampling=0
>
> optimizer_index_caching=100
>
> optimizer_index_cost_adj=1
>
> optimizer_secure_view_merging=FALSE
>
> query_rewrite_enabled=FALSE
>
> optimizer_mode=FIRST_ROWS
>
> session_cached_cursors=0
>
>
> *New environment- (19C, Exadata - X8):- *
>
> _buffered_publisher_flow_control_threshold = null
>
> _capture_publisher_flow_control_threshold =null
>
> _enable_query_rewrite_on_remote_objs = NULL
>
> _optimizer_cost_based_transformation = null
>
> nls_sort =NULL
>
> optimizer_dynamic_sampling=2
>
> optimizer_index_caching=0
>
> optimizer_index_cost_adj=100
>
> optimizer_secure_view_merging=TRUE
>
> query_rewrite_enabled=TRUE
>
> optimizer_mode=ALL_ROWS
> session_cached_cursors=200
>

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