AW: datapump and deferred_segment_creation

Hi,  

in my case setting the datapump's parameter segement_creation to the non-default value 0 (this value prevents the creation of segments for empty objects) saved me Terabytes of space and many hours of processing (creating segments of millions of empty partitions is time consuming). So the question, is there any reason or other use case behind the choice of the default value of this parameter, or maybe the default values are generally chosen haphazardly?
And why oracle introduces this parameter in datapump, which overrides the system parameter deferred_segment_creation, even the last one can be changed at session level? (one can use loggon trigger for datapump outside pl/sql)  

Best regards
Ahmed      

-----Original-Nachricht-----
Betreff: AW: datapump and deferred_segment_creation Datum: 2021-05-13T10:04:41+0200
Von: "ahmed.fikri_at_t-online.de" <ahmed.fikri_at_t-online.de> An: "ahmed.fikri_at_t-online.de" <ahmed.fikri_at_t-online.de>, "andy_at_klockmail.com" <andy_at_klockmail.com>      

thanks Andy and Dimitre!  

the parameter SEGMENT_CREATION is working.  

Best regards
Ahmed      

-----Original-Nachricht-----
Betreff: AW: datapump and deferred_segment_creation Datum: 2021-05-12T17:03:12+0200
Von: "ahmed.fikri_at_t-online.de" <ahmed.fikri_at_t-online.de> An: "andy_at_klockmail.com" <andy_at_klockmail.com>      

Thanks Andy.  

I'll check if it is working for Table and Index partitions. However, I wonder the default value of the parameter SEGMENT_CREATION is set to Y, whereas deferred_segment_creation is set to true.  

Best regards
Ahmed      

-----Original-Nachricht-----
Betreff: Re: datapump and deferred_segment_creation Datum: 2021-05-12T16:52:29+0200
Von: "Andy Klock" <andy_at_klockmail.com> An: "ahmed.fikri_at_t-online.de" <ahmed.fikri_at_t-online.de>      

Hi Ahmed,
> Is there any way to prevent oracle allocation 1M space for empty
partitions while using datapump.  

Take a look at the TRANSFORM parameter with the option for SEGMENT_CREATION:   <https://docs.oracle.com/en/database/oracle/oracle-database/19/sutil/datapump-import-utility.html#GUID-64FB67BD-EB67-4F50-A4D2-5D34518E6BDB>      

Andy K  

‐‐‐‐‐‐‐ Original Message ‐‐‐‐‐‐‐ On Wednesday, May 12, 2021 10:42 AM, ahmed.fikri_at_t-online.de <ahmed.fikri_at_t-online.de> wrote:  

    Hi all,      

    When importing partitioned tables using the datapump, segments are     allocated for empty table and index partitions (1MB each).     The parameter deferred_segment_creation is set to TRUE.     Is there any way to prevent oracle allocation 1M space for empty     partitions while using datapump.      

    Best regards
    Ahmed        



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