RE: upgrades, conversions and ora-600's! oh my!

From: Allen, Brandon <Brandon.Allen_at_OneNeck.com>
Date: Fri, 17 Aug 2007 16:05:03 -0700
Message-ID: <04DDF147ED3A0D42B48A48A18D574C45071FE2FB@NT15.oneneck.corp>

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_at_gmail.com]

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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Received on Fri Aug 17 2007 - 18:05:03 CDT