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alter table ... enable row movement [message #656794]

Wed, 19 October 2016 08:50

John Watson
Messages: 8960
Registered: January 2010
Location: Global Village

Senior Member

Just a minor question - does anyone know what enabling row movement actually does? Or how to see if row movement has been enabled for a table? As far as I can tell, it has no real effect at all. It is just that if you don't enable it, some things won't work. Right now, I can think of three cases where it is needed:

A partitioned table, if updating the partitioning key
Before using ALTER TABLE ... SHRINK SPACE
Some uses of DBMS_REDEFINITION

I'm sure there are others, I'ld be interested to know them all.

This is of no practical significance - I'm just curious. Thank you for any insight.

[Updated on: Wed, 19 October 2016 08:51]

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Re: alter table ... enable row movement [message #656801 is a reply to message #656794]

Wed, 19 October 2016 09:45

Michel Cadot
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Registered: March 2007
Location: Saint-Maur, France, https...

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Quote:

Just a minor question - does anyone know what enabling row movement actually does?

It enables rows to move. Smile

This feature was introduced to forbid some actions because some (I hope old) applications store row ids and access rows with this "key" to be faster.

Quote:

Right now, I can think of three cases where it is needed:

ALTER TABLE MOVE is another one.

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Re: alter table ... enable row movement [message #656804 is a reply to message #656801]

Wed, 19 October 2016 11:32

John Watson
Messages: 8960
Registered: January 2010
Location: Global Village

Senior Member

ALTER TABLE MOVE is online now, I just put up a little blog about it Smile

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Re: alter table ... enable row movement [message #656825 is a reply to message #656804]

Thu, 20 October 2016 02:41

Michel Cadot
Messages: 68716
Registered: March 2007
Location: Saint-Maur, France, https...

Senior Member
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Forgot to answer the question: "Or how to see if row movement has been enabled for a table?":
%_TABLES.ROW_MOVEMENT

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Re: alter table ... enable row movement [message #656844 is a reply to message #656825]

Thu, 20 October 2016 06:56

John Watson
Messages: 8960
Registered: January 2010
Location: Global Village

Senior Member

Stupid of me. Ta.

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