RE: Moving BLOBs from BASICFILES to SECUREFILES

Original white paper on the move (http://www.oracle.com/technetwork/database/securefilesmigrationpaper-130440.pdf). There are a lot more papers you can look at online.

I would also do a search on support.oracle.com to look at current bugs relative to your exact database version.  

For 300GB, yes it could take a day or two depending on the performance of your storage subsystem and the activity on the system/table.

There is always a chance of something failing or hanging the longer it runs.

You have the ability to change the storage options in the move as underneath the covers dbms_redefintion is using a new table to move into.  

Matthew Parker

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From: oracle-l-bounce_at_freelists.org [mailto:oracle-l-bounce_at_freelists.org] On Behalf Of Chen Zhou Sent: Tuesday, February 09, 2016 2:11 PM To: oracle-l_at_freelists.org
Subject: Moving BLOBs from BASICFILES to SECUREFILES  

Hi,

We have this table with BLOBs, which has high "enq:HW- contention" from time to time.

We already have event "44951 TRACE NAME CONTEXT FOREVER, LEVEL 1024" set. The only option I can think of is to move this BLOB from BASICFILE to SECUREFILE.

There has been discussion of doing this by using dbms_redefinition here, it seems to be a great tool that allows changing BLOB online.

This is a very important production database, will there be significant performance impact using this tool? If so, we may just schedule a maintenance time.

How long should we expect to redefine 300GB BLOBs? A few hours or a few days? Can it end up hanging?

Can I take the opportunity to move the BLOB to another tablespace during this redefinition process?

Thank you for your information.

Chen

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