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Expdb with parallel parameter writes files one at a time [message #639184] Thu, 02 July 2015 10:40 Go to next message
raziq
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Registered: July 2015
Location: Houston
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Here are all the details:
Oracle = 11.2.0.4.5 64bit
servername:tcnp%uname -a
SunOS servername 5.11 11.2 sun4v sparc sun4v
Spfile:cpu_count=64; parallel_max_servers=64; processes=250
expdp command used:
expdp username schemas=team_admin dumpfile=team_admin_schema_tcnp_041515_%U.dmp logfile=team_admin_schema_tcnp_041515.log parallel=8 FLASHBACK_TIME=SYSTIMESTAMP version=latest
What this does is it will export to 8 files, but it writes to these files one at a time. Not at the same time.

Thanks for your help.

Re: Expdb with parallel parameter writes files one at a time [message #639190 is a reply to message #639184] Thu, 02 July 2015 10:48 Go to previous messageGo to next message
BlackSwan
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Welcome to this forum.

Please read and follow the forum guidelines, to enable us to help you:

http://www.orafaq.com/forum/t/88153/0/ and read http://www.orafaq.com/forum/t/174502/


Thanks for sharing your comments
Re: Expdb with parallel parameter writes files one at a time [message #639195 is a reply to message #639184] Thu, 02 July 2015 11:05 Go to previous messageGo to next message
John Watson
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There are all sorts of restrictions on parallel export. If I remember correctly, you will only ever get one Data Pump worker process per table, and unless the table is over (I think) 500MB, you will not get PX servers exporting it in parallel. How many tables are there in that schema? How big are they?
Re: Expdb with parallel parameter writes files one at a time [message #639198 is a reply to message #639195] Thu, 02 July 2015 11:28 Go to previous messageGo to next message
Michel Cadot
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Right, each worker writes in its file and each segment (not necessary table if partitioned) is served by a unique worker.
Note that the segments are chosen by size descending.

Re: Expdb with parallel parameter writes files one at a time [message #639201 is a reply to message #639198] Thu, 02 July 2015 12:03 Go to previous messageGo to next message
raziq
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Thanks. Just checked and the largest table is 100 MB. Majority of the objects are indexes, lobindexes, lobsegments. Lobsegments = 141 GB. 420 objects.
Re: Expdb with parallel parameter writes files one at a time [message #639202 is a reply to message #639201] Thu, 02 July 2015 12:13 Go to previous messageGo to next message
Michel Cadot
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Indexes are irrelevant: only DDL text are exported.
If you set STATUS parameter you will periodically know what each worker is doing.

Re: Expdb with parallel parameter writes files one at a time [message #639204 is a reply to message #639202] Thu, 02 July 2015 13:39 Go to previous messageGo to next message
raziq
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Indexes are irrelevant: only DDL text are exported.
Not sure if I agree. When I do the import from my export files, indexes are there on the target database.
Re: Expdb with parallel parameter writes files one at a time [message #639205 is a reply to message #639204] Thu, 02 July 2015 13:39 Go to previous messageGo to next message
raziq
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I meant to say not sure if I understand Smile
Re: Expdb with parallel parameter writes files one at a time [message #639206 is a reply to message #639205] Thu, 02 July 2015 13:44 Go to previous messageGo to next message
Michel Cadot
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Only the DDL to create the indexes are exported, these DDL are executed during import and indexes recreated.
So exporting indexes take a short time.

Re: Expdb with parallel parameter writes files one at a time [message #639207 is a reply to message #639206] Thu, 02 July 2015 13:45 Go to previous messageGo to next message
raziq
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I see. So that would explain why the import takes longer as it is creating indexes in the target database.
Re: Expdb with parallel parameter writes files one at a time [message #639208 is a reply to message #639205] Thu, 02 July 2015 13:48 Go to previous messageGo to next message
BlackSwan
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>Not sure if I agree. When I do the import from my export files, indexes are there on the target database.
actual INDEX entry contains ROWID & FILEID where the row actually resides; which will be DIFFERENT between source & target tablespace.
Propagating cloned copy of source INDEX detail is a foolish exercise; since data rows in target are different from source tablespace.
for INDEX on DDL text exists & resides in exported data file.
Re: Expdb with parallel parameter writes files one at a time [message #639209 is a reply to message #639207] Thu, 02 July 2015 13:49 Go to previous messageGo to next message
Michel Cadot
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Longer that what? Than export, yes, and also because writes are slower than reads, you can test it importing without the indexes (and statistics, use EXCLUDE parameter).

[Edit: typo]

[Updated on: Thu, 02 July 2015 13:59]

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Re: Expdb with parallel parameter writes files one at a time [message #639210 is a reply to message #639209] Thu, 02 July 2015 13:51 Go to previous message
raziq
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Registered: July 2015
Location: Houston
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Thanks.
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