Re: rebuild indexes
Date: Fri, 18 Apr 2014 12:11:24 -0800
Message-ID: <535186EC.2040205_at_alaska.edu>
We use alter table ... shrink space cascade statement quite often for a couple of tables from which we delete rows regularly. You do need to enable row movement before doing the shrink space, and then disable row movement afterward. For a table that's spread across 6G, I've seen this process take many hours. We don't rebuild the indexes after, but I think that the cascade option also shrinks the indexes.
The advantages of shrink space over alter table ... move, include not needing to have any additional space available for the table since it is often quite large, and also not requiring any period of time when the table isn't available to users.
- Maureen
On 4/18/2014 10:54 AM, Tim Gorman wrote:
> ALTER TABLE ... MOVE (followed by index rebuilds) is one way to do this, but what they're probably asking for is ALTER
> TABLE ... SHRINK, which can be done "online" and doesn't necessarily require index rebuild afterward. More info here
> <http://docs.oracle.com/cd/B28359_01/server.111/b28310/schema003.htm#ADMIN10161>.
>
>
>
> On 4/18/2014 11:37 AM, Zelli, Brian wrote:
>>
>> One table has 14 rows and the other has 26. They say it is causing performance issues……
>>
>> Brian
>>
>> *From:*Andrew Kerber [mailto:andrew.kerber_at_gmail.com]
>> *Sent:* Friday, April 18, 2014 1:37 PM
>> *To:* Zelli, Brian
>> *Cc:* oracle-l (oracle-l_at_freelists.org)
>> *Subject:* Re: rebuild indexes
>>
>> How big is the table? He probably wants you to shrink it by eliminating unused blocks. The simplest way to do that
>> is by an alter table move command followed by alter index rebuild.
>>
>> Sent from my iPad
>>
>>
>> On Apr 18, 2014, at 12:26 PM, "Zelli, Brian" <Brian.Zelli_at_RoswellPark.org <mailto:Brian.Zelli_at_RoswellPark.org>> wrote:
>>
>> A vendor wants me to shrink a table. I’ve never shrunk one in oracle. Does that delete the data out of them?
>>
>> And then wants me to rebuild the associated indexes. Won’t they be empty after you shrink them?
>>
>> Brian
>>
>>
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-- Maureen English Lead Database Administrator University of Alaska Fairbanks, AK (907) 450-8329 -- http://www.freelists.org/webpage/oracle-lReceived on Fri Apr 18 2014 - 22:11:24 CEST