RE: null columns and memory?

There may be a question of context here as well.  

So long as we are talking about database blocks, the block will look identical whether it happens to reside on disk or in RAM. If and when you have a chunk of PL/SQL code that declares a VARCHAR2 (<2000) in order to read data from that block so you can act upon it programmatically, however, Oracle will reserve a chunk of memory for that local variable that is the maximum size it can attain..  

http://asktom.oracle.com/pls/ask/f?p=4950:8:::::F4950_P8_DISPLAYID:15426 06219593  

Justin Cave

Distributed Database Consulting, Inc.  

From: oracle-l-bounce_at_freelists.org
[mailto:oracle-l-bounce_at_freelists.org] On Behalf Of Paul Baumgartel Sent: Tuesday, September 27, 2005 4:27 PM To: oracle-l_at_freelists.org
Subject: Re: null columns and memory?  

In memory where? Space is reserved in DB blocks (formerly via PCTFREE, now via ASSM) for operations that increase the storage requirements of the block--such as updating a character string to a longer string, or supplying a value in a column that formerly contained none.

On 9/27/05, ryan_gaffuri_at_comcast.net <ryan_gaffuri_at_comcast.net > wrote:

Someone at work told me the following. Having trouble confirming it in the docs.  

If you have a table with a nullable varchar column. If the field is left null no space will be taken up in the database. However, space will be reserved in memory for the column. Is this correct?

-- 
Paul Baumgartel
paul.baumgartel_at_aya.yale.edu


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