RE: upgrades, conversions and ora-600's! oh my!
- From: "Allen, Brandon" <Brandon.Allen@xxxxxxxxxxx>
- To: "Robyn" <robyn.sands@xxxxxxxxx>, "oracle-l" <oracle-l@xxxxxxxxxxxxx>
- Date: Fri, 17 Aug 2007 16:05:03 -0700
If you do decide to go the exp/imp route, there are a lot of things you
can do to speed it up significantly - here are some notes on things you
might want to try. Unfortunately, if you do a character set conversion,
I'm not sure if you can use direct=y since I believe it requires the exp
character set to match that of the database, but maybe you can still do
the conversion on the import side.
On Export:
* DIRECT=Y
* RECORDLENGTH=65535
* Consider running export via multiple parallel sessions, e.g.
breaking it up by table or schema, and then doing the same for import.
* Exp/imp to/from named pipe to avoid disk I/O
* Verify OPTIMIZER_MODE != FIRST_ROWS - this can cause very poor
performance - see Metalink 181072.1 for more info (included below)
On Import:
* ALTER DATABASE NOARCHIVELOG; (set back to ARCHIVELOG and take
full backup after completion)
* BUFFER=10485760
* RECORDLENGTH=65535
o Especially important when going across platforms
* Optionally (depending on needs, version, etc.):
o COMMIT=N
o STATISTICS=NONE
o ANALYZE=N
o RECALCULATE_STATISTICS=N
o Increase size of online logs
o Use LMTs
o INDEXES=N (followed with INDEXFILE=Y and then parallel,
nologging creation of indexes after completion of table imports)
o Set _disable_logging=TRUE
o Set _wait_for_sync=FALSE
________________________________
From: Robyn [mailto:robyn.sands@xxxxxxxxx]
I am slowly accepting that we may have to recreate the databases.
if anyone has a specific suggestion on rebuilding a 2 TB database with
minimal downtime, please drop me a line.
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