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can I drop P-index of E-fact table after compression?

Hi, experts!

Maybe this question has been asked a lot of times, but I could not find the appropriate answer.

After an infocube has been compressed, its DB size increased in 2 times!

The reason is that the huge P-index was created. This index occupies the same DB space as the E-fact table! So P-index and E-table together are twice bigger than F-table was...

We have a lot of uncompressed infocube data in BW. So I am afraid of compressing it, because DB space is small.

Please explain me:

1) why this P-index is so huge?

2) can I drop it after compression has finished? is there any negative effects?

Thanks in advance.

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2 Answers

  • Best Answer
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    Former Member
    Oct 21, 2015 at 05:59 AM

    Hi Sergey,

    1) why this P-index is so huge?

    P-index is a B-tree index, where as the primary cube index are bitmap , you can search the difference between these two for better understanding.


    2) can I drop it after compression has finished? is there any negative effects?


    Index on E-fact are necessary when compressing request(s) [ in case you drop them , then you have to regenerate for this reason]  see note : 407260 for more info on this

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    • Former Member Sergey Musatov

      Hi Sergey,

      as long as you are passing the P-index as a parameter, it wont disturb primary index( as primary index creation and deletion are done separately in process chain).

      and to answer your interesting question, from my two cents, compression's are seen majorly in a huge advantage factor , take example of standard inventory cube? non-cumulative key figure should be compressed as they calculated on the fly. Not only this , any other cube for the matter when the F fact table is too high, compression reduces the records from F fact table which improves query performance.  Hope it helps! .. thanks

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    Former Member
    Oct 21, 2015 at 06:32 AM

    Hi,

    Question 2 : You can drop your P index after compression as this is related to the F table.

    How ever the P index is required for the compression and will be used during the compression.

    Pl refer sap note 407260.

    thanks,

    -j

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    • Former Member Sergey Musatov

      Hi Sergey,

      Please refer the sap note mentioned above. You can also check this relation in SE11 /14.

      If the P index is created before the compression it should not give any issue. Just make sure that this index is there (also statistics are updated) before the compression . Please refer the suggestion from Jyothi above how to do it.

      Thanks.

      -J