Stored Procedure comments impact performance???

Question

Stored Procedure comments impact performance???

sjohnst4

SSC Veteran

Points: 236
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May 29, 2007 at 7:00 am

#179133

Hi
We are currently putting together best practices for writing Stored Procedures for Sql Server 2005 within our company. I would like to have a header at the top of each stored procedure stating, description, params, history etc etc. However a member of the team has indicated that putting extra comments within a stored procedure file will impact performance of the database when the procedure is called. Then reason stated due to the stored procedure being larger in size so when the database has to "pull out" the procedure every time it is run, it will take longer.
Not being an expert I can't really argure for or against from a performance point of view, only from a maintainability point of view. I was also under the impression that a stored procedure got compiled after first being run so any excess comments would not impace after it had been called once.
Any advice would be greatly appreciated.
Steve
March 28, 2024 at 2:46 am

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shahzadtariq SSC-Addicted Points: 424 More actions · Answer 1

Hi,

I don't think it will affect on stored procedure performance, because stored procedure are pre-compiled although it may take to execute first time but after that it should not impact the performance of stored procedure.

Andy Warren SSC Guru Points: 119902 More actions · Answer 2

Agree. Header comments are a good idea, as are inline comments. I'd suggest mirroing whatever commenting guidelines you use for 'real' code. Keep it simple, stick to it!

Andy
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Jeff Moden SSC Guru Points: 1004363 More actions · Answer 3

Why speculate Do a test Run the following code several times and tell your team mate "Sorry, you're not going to get out of properly documenting code with that old wive's tale"....

--===== Let's do the experiment in a "safe place"

USE TempDb

GO

--===== Create a proc to do something simple with no comments

CREATE PROCEDURE TestWithoutComments

AS

DECLARE @Bitbucket VARCHAR(40)

SELECT @Bitbucket = AU_LName

FROM Pubs.dbo.Authors

GO

--===== Create the exact same proc but with slight more than 16k of

-- comment in the "header"

CREATE PROCEDURE TestWith16kComments

AS

/*

16k of comments follow...

XXXXXXXXX XXXXXXXXX XXXXXXXXX XXXXXXXXX XXXXXXXXX XXXXXXXXX XXXXXXXXX XXXXXXXXX XXXXXXXXX XXXXXXXXX XXXXXXXXX XXXXXXXXX XXXXXXXXX XXXXXXXXX XXXXXXXXX XXXXXXXXX XXXXXXXXX XXXXXXXXX XXXXXXXXX XXXXXXXXX XXXXXXXXX XXXXXXXXX XXXXXXXXX XXXXXXXXX XXXXXXXXX XXXXXXXXX XXXXXXXXX XXXXXXXXX XXXXXXXXX XXXXXXXXX XXXXXXXXX XXXXXXXXX XXXXXXXXX XXXXXXXXX XXXXXXXXX XXXXXXXXX XXXXXXXXX XXXXXXXXX XXXXXXXXX XXXXXXXXX XXXXXXXXX XXXXXXXXX XXXXXXXXX XXXXXXXXX XXXXXXXXX XXXXXXXXX XXXXXXXXX XXXXXXXXX XXXXXXXXX XXXXXXXXX XXXXXXXXX XXXXXXXXX XXXXXXXXX XXXXXXXXX XXXXXXXXX XXXXXXXXX XXXXXXXXX XXXXXXXXX XXXXXXXXX XXXXXXXXX XXXXXXXXX XXXXXXXXX XXXXXXXXX XXXXXXXXX XXXXXXXXX XXXXXXXXX XXXXXXXXX XXXXXXXXX XXXXXXXXX XXXXXXXXX XXXXXXXXX XXXXXXXXX XXXXXXXXX XXXXXXXXX XXXXXXXXX XXXXXXXXX XXXXXXXXX XXXXXXXXX XXXXXXXXX XXXXXXXXX XXXXXXXXX XXXXXXXXX XXXXXXXXX XXXXXXXXX XXXXXXXXX XXXXXXXXX XXXXXXXXX XXXXXXXXX XXXXXXXXX XXXXXXXXX XXXXXXXXX XXXXXXXXX XXXXXXXXX XXXXXXXXX XXXXXXXXX XXXXXXXXX XXXXXXXXX XXXXXXXXX XXXXXXXXX XXXXXXXXX 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XXXXXXXXX

*/

DECLARE @Bitbucket VARCHAR(40)

SELECT @Bitbucket = AU_LName

FROM Pubs.dbo.Authors

GO

--===================================================================

-- Run each proc 10,000 times to find which is faster...

--===================================================================

--===== Declare a loop counter and a duration "timer"

DECLARE @Counter INT

DECLARE @StartTime DATETIME

--===== Run the code with no comments and then report the duration

SET @StartTime = GETDATE()

SET @Counter = 0

WHILE @Counter <= 10000

BEGIN

EXEC TestWithoutComments

SET @Counter = @Counter + 1

END

PRINT STR(DATEDIFF(ms,@StartTime,GETDATE())) + ' Time to run without comments'

--===== Run the code with no comments and then report the duration

SET @StartTime = GETDATE()

SET @Counter = 0

WHILE @Counter <= 10000

BEGIN

EXEC TestWith16kComments

SET @Counter = @Counter + 1

END

PRINT STR(DATEDIFF(ms,@StartTime,GETDATE())) + ' Time to run with comments'

--===== Test complete... do a little housekeeping

DROP PROCEDURE TestWithoutComments, TestWith16kComments

--Jeff Moden

RBAR is pronounced "ree-bar" and is a "Modenism" for Row-By-Agonizing-Row.
First step towards the paradigm shift of writing Set Based code:
________Stop thinking about what you want to do to a ROW... think, instead, of what you want to do to a COLUMN.

Change is inevitable... Change for the better is not.

Helpful Links:
How to post code problems
How to Post Performance Problems
Create a Tally Function (fnTally)

Greg Milner SSCrazy Points: 2425 More actions · Answer 4

I find that the simpler the better with header info. I also like to put a header in the extended property of tables as as a property called "HeaderInfo."

I also usually DON'T put in param info in the header anymore unless there are more than 3 params and/or the params are weird. You'd be surprised how little you need to document params if you just name them well.

Here's a template what I use:

/*=========================================================================

Title: Descriptive_Title_Here

Script: Script_file_name.sql

Purpose: SHORT_DESCRIPTION

Issue/Ticket No: 00000000

Example Usage:

Create/Change History:

DateTime - AuthorName: Created_Or_ChangeNote_Here

Note:

A_Note_goes_here_concerning_params_special_considerations_output_etc

=========================================================================*/

All the boilerplate is with underscores so you can click once to select it and type over it.

I used to keep this in a .tql template but now I use HotKeyz and paste it in with CTRL+SHIFT+H. Much faster.

I put it in procs, functions, views triggers (right after params and before the first "AS") and extended properties of tables. Each time the object is changed, I kick down the DateTime - AuthorName line so the most recent change is on top.

This really helps us stay SUX... er... SOX compliant.

Cheers.

G. Milner

Jeff Moden SSC Guru Points: 1004363 More actions · Answer 5

Concur... that's just about the same as what I use for header info. And I document any parameters where such documentation belongs... next to the parameters in the code

--Jeff Moden

RBAR is pronounced "ree-bar" and is a "Modenism" for Row-By-Agonizing-Row.
First step towards the paradigm shift of writing Set Based code:
________Stop thinking about what you want to do to a ROW... think, instead, of what you want to do to a COLUMN.

Change is inevitable... Change for the better is not.

Helpful Links:
How to post code problems
How to Post Performance Problems
Create a Tally Function (fnTally)

Michael Earl-395764 SSC Guru Points: 53873 More actions · Answer 6

Take the developer that does not want to comment his code and beat him with any programming best-practices book. I'll lay down $20 that says he will end up producing some completely unmanagable code before he leaves your company.

Comments have no significant impact on stored procedure performance. There is a tiny hit each time stored procedure text wraps to another record in the Syscomments table, but it is less than nothing.

In addition, once the procedure has been run once and SQL has a usable execution plan in cache, the text will not be retrieved again and comments have zero impact on performance.

However, I do like the test of the procedure with a huge comment that was posted earlier.