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sushanth bobby
Senior Member
Joined: 29 Jul 2008
Posts: 1020
Location: India
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Hi,
I have doubt regarding adding a column in DB2 table. A column can be added to a db2 table using ALTER TABLE statement.
But, why most of the DBA's prefer to.
Unload the table
Drop the table
Create the table dropped table with new column.
Create indexes
Load the table
Is there any reason for this process. |
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Prasanthhere
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Joined: 03 Aug 2005
Posts: 306
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IF the column is added not at the end and if its added in between a table only the DBA'S prefer to
Unload the table
Drop the table
Create the table dropped table with new column.
Create indexes
Load the table
If the column is added at the end of the table and if the column is of NOT NULL WITH DEFAULT the tool ( PLA) will capture the change the as ALTER and Not as dropping the table and recreating the same .The case is reverse when the column need to be added as a NOT NULL column |
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sushanth bobby
Senior Member
Joined: 29 Jul 2008
Posts: 1020
Location: India
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| Hi Prasanth, "PLA" you refering to, is it Platinum Tool |
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Prasanthhere
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Joined: 03 Aug 2005
Posts: 306
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| YES Very much . |
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sushanth bobby
Senior Member
Joined: 29 Jul 2008
Posts: 1020
Location: India
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| What will happen in the CASE of expanding the COLUMN size. |
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Prasanthhere
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Joined: 03 Aug 2005
Posts: 306
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| Expanding the column Size also depends on where the column lies . On analysis using the tool if the column is at the end the Alter would be the statement getting generated. |
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dick scherrer
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Joined: 23 Nov 2006
Posts: 19244
Location: Inside the Matrix
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Hello,
Something else that might be considered is the value of having a common process regardless of the current modification requirement.
The unload, drop, create, re-load works every time. |
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sushanth bobby
Senior Member
Joined: 29 Jul 2008
Posts: 1020
Location: India
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| Quote: |
| Something else that might be considered is the value of having a common process regardless of the current modification requirement. - Dick Scherrer |
| Quote: |
| If the column is added at the end of the table and if the column is of NOT NULL WITH DEFAULT... - Prasanth |
In this case ALTER would be enough. But, having it as a common process regardless of the current modification.
Wouldn't that be consuming time. |
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dick scherrer
Moderator Emeritus
Joined: 23 Nov 2006
Posts: 19244
Location: Inside the Matrix
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Hello,
| Quote: |
| Wouldn't that be consuming time. |
Typically, no.
Doing the same process repeatedly (espcially after it is automated) is safer and really takes no significant amount of extra time.
Many organizations do not permit ALTER for production work.
If you are "just playing around", alter might be ok for personal experimentation. |
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sushanth bobby
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Joined: 29 Jul 2008
Posts: 1020
Location: India
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| Oh, Thank You Dick. I didn't know that. |
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dick scherrer
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Joined: 23 Nov 2006
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You're welcome 
d |
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