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About Null_BitMap

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AskSQLTeam
Ask SQLTeam Question

0 Posts

Posted - 2006-03-08 : 08:53:40

Anoop writes "I want to know what is Null Bitmap?"

spirit1
Cybernetic Yak Master

11752 Posts

Posted - 2006-03-08 : 09:06:32

it's a bitmap that specifies which columns in a table allow nulls to be inserted.

Go with the flow & have fun! Else fight the flow

Frank Kalis
Constraint Violating Yak Guru

413 Posts

Posted - 2006-03-09 : 03:45:22

quote:

it's a bitmap that specifies which columns in a table allow nulls to be inserted.

Slightly incorrect.
The NULL bitmap is always present in SQL Server 2000, even if all columns are constrained to NOT NULL. The NULL bitmap only tracks which column actually contain the NULL marker.

--
Frank Kalis
Microsoft SQL Server MVP
http://www.insidesql.de
Heute schon gebloggt? http://www.insidesql.de/blogs

spirit1
Cybernetic Yak Master

11752 Posts

Posted - 2006-03-09 : 05:06:17

ok i got to now...

what was slightly incorrect??

Go with the flow & have fun! Else fight the flow

Frank Kalis
Constraint Violating Yak Guru

413 Posts

Posted - 2006-03-09 : 06:10:26

Read my answer.

The NULL bitmap does *not* indicate, which columns allow NULL to be inserted, but rather indicates which column *actually* contain a NULL.

--
Frank Kalis
Microsoft SQL Server MVP
http://www.insidesql.de
Heute schon gebloggt? http://www.insidesql.de/blogs

spirit1
Cybernetic Yak Master

11752 Posts

Posted - 2006-03-09 : 06:47:59

ahhhh. cool

Go with the flow & have fun! Else fight the flow

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