Re: Proposal for Null Bitmap Optimization(for Trailing NULLs) - Mailing list pgsql-hackers

From Gokulakannan Somasundaram
Subject Re: Proposal for Null Bitmap Optimization(for Trailing NULLs)
Date
Msg-id 9362e74e0712170523x15b168c9ve65cf83d1956283a@mail.gmail.com
Whole thread Raw
In response to Re: Proposal for Null Bitmap Optimization(for Trailing NULLs)  (Simon Riggs <simon@2ndquadrant.com>)
List pgsql-hackers


On Dec 17, 2007 3:28 PM, Simon Riggs <simon@2ndquadrant.com> wrote:
On Mon, 2007-12-17 at 13:10 +0530, Gokulakannan Somasundaram wrote:

>     Currently we check for the existence of NULL values in the tuple
> and we set the has_null flag. If the has_null flag is present, the
> tuple will be storing a null bitmap. What i propose is

Will this work for ALTER TABLE when adding and dropping columns?
When we drop columns, it is not at all an issue. When we add columns, by default they have null values. If we want to set default, postgres allows it only for new inserts. Can you think of any specific instance.


Another idea is to store the bitmap from the first nullable column.
This is a different idea. I like this. I will think about this also.
 


Some of these ideas have been discussed before, so I would check the
archives thoroughly. Most everything has if you look closely enough.
 
I have done a fair amount of search in the archives. But if you remember any please notify me about it.
 


--
 Simon Riggs
 2ndQuadrant   http://www.2ndQuadrant.com




--
Thanks,
Gokul.
CertoSQL Project,
Allied Solution Group.
(www.alliedgroups.com )

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