Comments on: SQL SERVER – Disable CHECK Constraint – Enable CHECK Constraint

By: SQL SERVER – Various Ways to Create Constraints – Quiz – Puzzle – 17 of 31 « SQL Server Journey with SQL Authority

Wed, 18 Jan 2012 01:31:48 +0000

[...] Creating Table Creating Primary Key, Foreign Key and Default Constraint How to ALTER CONSTRAINT Disable CHECK Constraint – Enable CHECK Constraint Query to Display Foreign Key Relationships and Name of the Constraint for Each Table in Database [...]

By: Golden

Golden — Sun, 08 Jan 2012 13:21:22 +0000

I am updating the tables in 13 databases on my one application. Many of them reffering to each other. I have disabled the constraints, updated tables and enabled.

Just I want to know if any impact on database health by doing this changes in constraints.

Response required.

Thanks
AKHILESH

By: Senthil Kumar K.S

Senthil Kumar K.S — Thu, 15 Dec 2011 11:24:32 +0000

How to check status of column constraint ( enabled or disabled)

By: Senthil Kumar K.S

Senthil Kumar K.S — Thu, 15 Dec 2011 11:02:04 +0000

How to check status of column constraints.(Enable or disabled).

By: Jayaram

Jayaram — Fri, 02 Sep 2011 05:30:01 +0000

How to maintain check constraint with two databases say db1 and db2?

By: KumarHarsh

KumarHarsh — Thu, 07 Oct 2010 11:07:50 +0000

Hi,
Suppose,I disable the index.
Perform some task
Again I enable it.
when I enable the index again whether the data will be reindexed or it will remain same.
If it gets reindexed how long will it take to reindex for 13 crore / 130 million record.

Thanks.

By: Niraj Singh Pawar

Niraj Singh Pawar — Tue, 20 Jul 2010 11:08:32 +0000

how to use Check constraint in If conditions

By: Ryan Anthony

Ryan Anthony — Thu, 12 Nov 2009 21:15:29 +0000

You don’t need to use With Check when re-enabling a check constraint, it accomplishes something entirely different than re-enabling the check constraint. By default for Alter Table, With Nocheck is used for re-enabling check constraints. Specifying With Check looks at all existing data to make sure it satisfies the check constraint. If you can safely assume that it already does, then you don’t need to specify that.

I disable check constraints to get replicating dbs that have gotten out of sync back in sync.

By: Brian Tkatch

Brian Tkatch — Thu, 12 Nov 2009 14:19:29 +0000

@Dave so you disabled the NOT NULL CONSTRAINT?

@Imran So you disable the FK.

I think FK is the most likely CONSTRAINT to be disabled, and NOT NULL being a close second. A CHECK CONSTRAINT (not the one for NOT NULL which although is a CHECK CONSTRAINT, is specified differently) is not really disabled too often.

It would be interesting to see what types a CHECK CONSTRAINT are actually used, and which types are disabled.

By: Imran Mohammed

Imran Mohammed — Thu, 12 Nov 2009 04:20:07 +0000

I remember, We had a huge database that collects statistics around 45 GB and we had very less space on server, it created many problems.

Finally one fine day, they asked me if I could help, they said, they want to clean historical data. Vendor suggested them to use front End to Purge (Delete) data. It was like tons of records… and would take for ever more than a day, to purge data, because you could purge very few records at one time.

I studied their database and came to conclusion that there are only 3 tables that had huge amount of data… and other tables were referring to them.

I gave them a solution to Truncate those 3 tables. For that I had to drop foreign key constraint. I dropped Forign Key Constraint, Truncated tables and built Foreign Key constraint again.

Boom… 3 seconds… Database size came to less than 0.5 GB.

Result: I was awarded DBA of the week :)

Note: I did enough research on the database, and I ensured that truncating data from 3 tables wont effect application.

~ IM.

By: Dave

Dave — Thu, 12 Nov 2009 02:23:13 +0000

I have disabled FKs in the past for purposes of data loading, where data coming into constrained column was going to have nulls.

After loading and cleaning the constraints were re-enabled.