Sql – Advantages to Vertical Partitioning of Table

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(Note that this situation isn't exactly how it is, but I made this as an example)

I have an entity in a table with data that is updated every 5 seconds (Kinematic Data: Speed, Heading, Lat, Long, and PositionTime), and other data that is updated hardly at all, if ever (Color, Make, OriginTime).

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Now my boss wants me to partition this data into separate tables in our database (With a One to One Relationship), as so:

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He makes it sound "obvious" that it should be this way, but is there really any advantages to having this data separated as so for inserting and updating (For instance if I put an index on Color or Make)?

Best Answer

It might make sense to do vertical partitioning like this. Or it might not.

When you use a MVCC based engine, each time you update a row, it generally* copies the entire row and creates a new one with the modifications. This is so that other transactions which do not yet see the update can continue to read the original row if they need to.

This means that updating a few small columns frequently in a very wide row causes the database to do a lot more writes than it needs to.

But not that many, because generally the engine will only sync its transaction log, which will be the same size regardless of the size of non-updated columns, and also because the data rows are usually stored in blocks where a whole block needs to be written anyway, regardless of how much of it changed.

So it sounds like a potentially pointless optimisation, which like any other, should be considered on the grounds of a) IS there really a performance problem (i.e. is ANY optimisation needed) and b) Is this particular optimisation the best way of fixing it?

I think the chance of a) is unlikely, and b) is also unlikely, so the chances of this being required is approximately unlikely-squared.

* Some engines make an exception for very large columns such as big BLOBs or text columns, which are held elsewhere and not copied if other columns in the row are updated.

Syntax:

ALTER TABLE {TABLENAME} 
ADD {COLUMNNAME} {TYPE} {NULL|NOT NULL} 
CONSTRAINT {CONSTRAINT_NAME} DEFAULT {DEFAULT_VALUE}
WITH VALUES

Example:

ALTER TABLE SomeTable
        ADD SomeCol Bit NULL --Or NOT NULL.
 CONSTRAINT D_SomeTable_SomeCol --When Omitted a Default-Constraint Name is autogenerated.
    DEFAULT (0)--Optional Default-Constraint.
WITH VALUES --Add if Column is Nullable and you want the Default Value for Existing Records.

Notes:

Optional Constraint Name:
If you leave out CONSTRAINT D_SomeTable_SomeCol then SQL Server will autogenerate
a Default-Contraint with a funny Name like: DF__SomeTa__SomeC__4FB7FEF6

Optional With-Values Statement:
The WITH VALUES is only needed when your Column is Nullable
and you want the Default Value used for Existing Records.
If your Column is NOT NULL, then it will automatically use the Default Value
for all Existing Records, whether you specify WITH VALUES or not.

How Inserts work with a Default-Constraint:
If you insert a Record into SomeTable and do not Specify SomeCol's value, then it will Default to 0.
If you insert a Record and Specify SomeCol's value as NULL (and your column allows nulls),
then the Default-Constraint will not be used and NULL will be inserted as the Value.

Notes were based on everyone's great feedback below.
Special Thanks to:
@Yatrix, @WalterStabosz, @YahooSerious, and @StackMan for their Comments.

Sql – Insert results of a stored procedure into a temporary table

You can use OPENROWSET for this. Have a look. I've also included the sp_configure code to enable Ad Hoc Distributed Queries, in case it isn't already enabled.

CREATE PROC getBusinessLineHistory
AS
BEGIN
    SELECT * FROM sys.databases
END
GO

sp_configure 'Show Advanced Options', 1
GO
RECONFIGURE
GO
sp_configure 'Ad Hoc Distributed Queries', 1
GO
RECONFIGURE
GO

SELECT * INTO #MyTempTable FROM OPENROWSET('SQLNCLI', 'Server=(local)\SQL2008;Trusted_Connection=yes;',
     'EXEC getBusinessLineHistory')

SELECT * FROM #MyTempTable

Best Answer

Related Solutions

Sql – Add a column with a default value to an existing table in SQL Server

Syntax:

Example:

Notes:

Sql – Insert results of a stored procedure into a temporary table

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