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Home -> Community -> Usenet -> c.d.o.server -> Re: EXP/IMP - Different Space used
On 26 Dec 1998 04:54:38 GMT, "Sanjay Hans"
<sanhans_at_mbox5.singnet.com.sg> wrote:
>I am trying to migrate from Oracle 7.3.3 to Oracle 8.0.4 using full export
>backup as system user. I have tried two option for taking the export backup
>1) compress=y 2) compress=n.
>
>To my surprise, on importing the export backup (with options compress=y and
>compress=n), the space utilisations for the tablespace containing indexes
>are different (I have different tablespace for data & index).
>...[SNIP]...
>
>The tablespace containing indexes is having only 291,823,616 bytes free on
>importing the export backup with compress=y whereas
>the tablespace containing indexes is having 1374,478,336 bytes free on
>importing the export backup with compress=n.
>Please note that the source database (from where export is taken) is also
>showing 291,823,616 bytes free only.
>
>Would appreciate, If you can expain the reason for different space
>utilisations.
Check if you have any segments in your INDEX_TAB tablespace that are created with MINEXTENTS > 1. In this case the occupied space after importing compressed export will be larger than in the original (exported) database.
Consider you have an index created with the following storage
parameters: MINEXTENTS=6, INITIAL=50M, NEXT=10M, PCTINCREASE=0. After
creation your index segment will have 100M (50M + 5*10M). If you now
export this segment with the COMPRESS=Y and import it back, it will
occupy 150M! Because of the compress parameter the initial extend will
be of size 100M (original 6 extents compressed into a single extend of
the size equal to the sum of all original extents), and there will
also be aditional 5 extents of 10M (because of the storage parameter
MINEXTENTS=6).
>Thanks in advance.
HTH,
Jurij Modic <jmodic_at_src.si>
Certified Oracle7 DBA (OCP)
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