Click here to monitor SSC
SQLServerCentral is supported by Red Gate Software Ltd.
 
Log in  ::  Register  ::  Not logged in
 
 
 
        
Home       Members    Calendar    Who's On


Add to briefcase 12»»

Maximum Concurrent Users in a day Expand / Collapse
Author
Message
Posted Friday, February 8, 2013 9:53 AM
Mr or Mrs. 500

Mr or Mrs. 500Mr or Mrs. 500Mr or Mrs. 500Mr or Mrs. 500Mr or Mrs. 500Mr or Mrs. 500Mr or Mrs. 500Mr or Mrs. 500

Group: General Forum Members
Last Login: Tuesday, December 9, 2014 5:04 AM
Points: 598, Visits: 1,653
Hi all

I have a table which contains login and logout times for a large set of users, and we are wanting to know how to code it to pull back the maximum number of users who are logged on at any one time during that day.

I have got no where with this at present I have searched the internet and found something here:

http://stackoverflow.com/questions/1117004/find-number-of-concurrent-users-in-a-sql-records

However I can not figure out the solution mentioned and have been unable to get it to work. If anyone has any thoughts on how best to do this I would be grateful

Thanks.
Post #1417803
Posted Friday, February 8, 2013 9:59 AM


Hall of Fame

Hall of FameHall of FameHall of FameHall of FameHall of FameHall of FameHall of FameHall of FameHall of Fame

Group: General Forum Members
Last Login: Tuesday, January 28, 2014 8:15 AM
Points: 3,065, Visits: 4,639
Kwisatz78 (2/8/2013)
Hi all

I have a table which contains login and logout times for a large set of users, and we are wanting to know how to code it to pull back the maximum number of users who are logged on at any one time during that day.

I have got no where with this at present I have searched the internet and found something here:

http://stackoverflow.com/questions/1117004/find-number-of-concurrent-users-in-a-sql-records

However I can not figure out the solution mentioned and have been unable to get it to work. If anyone has any thoughts on how best to do this I would be grateful

Thanks.


One way would be to create a buckets table with one row representing each and every single minute of the day - is that granularity enough for you? - then, for each row on your login/logout table add 1 to all the buckets representing minutes the particular user was logged into the system.

At the end of the process just select the bucket with max() and the minute of the day represented by the winning bucket plus the value of the bucket would tell when the max() number of users was logged in and how many of them where logged in at the time.

Hope this helps.


_____________________________________
Pablo (Paul) Berzukov

Author of Understanding Database Administration available at Amazon and other bookstores.

Disclaimer: Advice is provided to the best of my knowledge but no implicit or explicit warranties are provided. Since the advisor explicitly encourages testing any and all suggestions on a test non-production environment advisor should not held liable or responsible for any actions taken based on the given advice.
Post #1417810
Posted Friday, February 8, 2013 12:14 PM


Ten Centuries

Ten CenturiesTen CenturiesTen CenturiesTen CenturiesTen CenturiesTen CenturiesTen CenturiesTen Centuries

Group: General Forum Members
Last Login: Tuesday, September 3, 2013 8:24 AM
Points: 1,240, Visits: 5,421
The solution provided in your link is likely to be the fastest. (It essentially the same as what Paul is suggesting, but limiting the buckets to only the specific login times.) If you post what you have already tried and where you ran into problems, we can help you understand how it works.

J. Drew Allen
Business Intelligence Analyst
Philadelphia, PA
Post #1417867
Posted Saturday, February 9, 2013 3:33 PM


SSC-Dedicated

SSC-DedicatedSSC-DedicatedSSC-DedicatedSSC-DedicatedSSC-DedicatedSSC-DedicatedSSC-DedicatedSSC-DedicatedSSC-DedicatedSSC-DedicatedSSC-DedicatedSSC-DedicatedSSC-Dedicated

Group: General Forum Members
Last Login: Today @ 12:22 AM
Points: 35,772, Visits: 32,443
drew.allen (2/8/2013)
The solution provided in your link is likely to be the fastest. (It essentially the same as what Paul is suggesting, but limiting the buckets to only the specific login times.) If you post what you have already tried and where you ran into problems, we can help you understand how it works.


If you're talking about Alex K's solution, it's absolutely horrible. If you take a look at the Actual Execution Plan, it has a full blown accidental CROSS JOIN in it for smaller numbers of rows and a full blown Triangular Join in it for larger numbers. I wouldn't use that code if it was the only way to get this problem done.


--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."

(play on words) "Just because you CAN do something in T-SQL, doesn't mean you SHOULDN'T." --22 Aug 2013

Helpful Links:
How to post code problems
How to post performance problems
Post #1418064
Posted Saturday, February 9, 2013 6:13 PM


SSCrazy Eights

SSCrazy EightsSSCrazy EightsSSCrazy EightsSSCrazy EightsSSCrazy EightsSSCrazy EightsSSCrazy EightsSSCrazy EightsSSCrazy EightsSSCrazy Eights

Group: General Forum Members
Last Login: Today @ 12:15 AM
Points: 9,928, Visits: 11,207
Kwisatz78 (2/8/2013)
I have a table which contains login and logout times for a large set of users, and we are wanting to know how to code it to pull back the maximum number of users who are logged on at any one time during that day.

This was the subject of a series of articles by Itzik Ben-Gan. The fastest solution found was submitted by, among others, our very own R Barry Young. You can read all about it here:

http://www.sqlmag.com/article/tsql3/calculating-concurrent-sessions-part-3-103407

Be sure to read the whole thing, not just the first page. I have a SQLCLR solution that beats that by around 30% but unless you really need that extra bit of speed (and are quite expert with T-SQL and SQLCLR) I would stick with Barry's code.




Paul White
SQL Server MVP
SQLblog.com
@SQL_Kiwi
Post #1418070
Posted Saturday, February 9, 2013 10:11 PM


SSC-Dedicated

SSC-DedicatedSSC-DedicatedSSC-DedicatedSSC-DedicatedSSC-DedicatedSSC-DedicatedSSC-DedicatedSSC-DedicatedSSC-DedicatedSSC-DedicatedSSC-DedicatedSSC-DedicatedSSC-Dedicated

Group: General Forum Members
Last Login: Today @ 12:22 AM
Points: 35,772, Visits: 32,443
SQL Kiwi (2/9/2013)
Kwisatz78 (2/8/2013)
I have a table which contains login and logout times for a large set of users, and we are wanting to know how to code it to pull back the maximum number of users who are logged on at any one time during that day.

This was the subject of a series of articles by Itzik Ben-Gan. The fastest solution found was submitted by, among others, our very own R Barry Young. You can read all about it here:

http://www.sqlmag.com/article/tsql3/calculating-concurrent-sessions-part-3-103407

Be sure to read the whole thing, not just the first page. I have a SQLCLR solution that beats that by around 30% but unless you really need that extra bit of speed (and are quite expert with T-SQL and SQLCLR) I would stick with Barry's code.


Freakin' awesome link, Paul. I was able to modify Barry's code to also correctly populate the MX column for the Logoffs so that I could graph the "valleys" as well as the "peaks". I've been trying to do this solution in a similar fashion and got seriously hooked because I just didn't see the 2:1 ratio that Barry included in his final formula. Thanks for posting the link. It's definitely a keeper.

Barry, if you read this post, I know it's been 3 years since you wrote the code and that article came out but thanks a million to you for writing the code and to Itzik for 'splainin' it.


--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."

(play on words) "Just because you CAN do something in T-SQL, doesn't mean you SHOULDN'T." --22 Aug 2013

Helpful Links:
How to post code problems
How to post performance problems
Post #1418075
Posted Saturday, February 9, 2013 10:35 PM


SSCrazy Eights

SSCrazy EightsSSCrazy EightsSSCrazy EightsSSCrazy EightsSSCrazy EightsSSCrazy EightsSSCrazy EightsSSCrazy EightsSSCrazy EightsSSCrazy Eights

Group: General Forum Members
Last Login: Today @ 12:15 AM
Points: 9,928, Visits: 11,207
Jeff Moden (2/9/2013)
Freakin' awesome link, Paul. I was able to modify Barry's code to also correctly populate the MX column for the Logoffs so that I could graph the "valleys" as well as the "peaks". I've been trying to do this solution in a similar fashion and got seriously hooked because I just didn't see the 2:1 ratio that Barry included in his final formula. Thanks for posting the link. It's definitely a keeper.

Yes, it's very clever but quite simple at the same time, once the concepts sink in. Once SQL Server supports proper ordered aggregates, the problem will be trivial.




Paul White
SQL Server MVP
SQLblog.com
@SQL_Kiwi
Post #1418077
Posted Sunday, February 10, 2013 12:07 AM


SSC-Dedicated

SSC-DedicatedSSC-DedicatedSSC-DedicatedSSC-DedicatedSSC-DedicatedSSC-DedicatedSSC-DedicatedSSC-DedicatedSSC-DedicatedSSC-DedicatedSSC-DedicatedSSC-DedicatedSSC-Dedicated

Group: General Forum Members
Last Login: Today @ 12:22 AM
Points: 35,772, Visits: 32,443
I've worked with the "difference between ROW_NUMs" a lot and, like you say, once you've got the concept down, it's very simple. Heh... unless you did like I originaly did and miss the bloody 2:1 ratio that Barry used in his final calculation.

Thanks again, Paul.


--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."

(play on words) "Just because you CAN do something in T-SQL, doesn't mean you SHOULDN'T." --22 Aug 2013

Helpful Links:
How to post code problems
How to post performance problems
Post #1418082
Posted Sunday, February 10, 2013 1:56 PM


SSC-Dedicated

SSC-DedicatedSSC-DedicatedSSC-DedicatedSSC-DedicatedSSC-DedicatedSSC-DedicatedSSC-DedicatedSSC-DedicatedSSC-DedicatedSSC-DedicatedSSC-DedicatedSSC-DedicatedSSC-Dedicated

Group: General Forum Members
Last Login: Today @ 12:22 AM
Points: 35,772, Visits: 32,443
@Kwisatz78,

Are you all set now or do you need some additional help?


--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."

(play on words) "Just because you CAN do something in T-SQL, doesn't mean you SHOULDN'T." --22 Aug 2013

Helpful Links:
How to post code problems
How to post performance problems
Post #1418133
Posted Sunday, February 10, 2013 2:02 PM
Mr or Mrs. 500

Mr or Mrs. 500Mr or Mrs. 500Mr or Mrs. 500Mr or Mrs. 500Mr or Mrs. 500Mr or Mrs. 500Mr or Mrs. 500Mr or Mrs. 500

Group: General Forum Members
Last Login: Tuesday, December 9, 2014 5:04 AM
Points: 598, Visits: 1,653
Crickey guys thanks very much for all the replies, I will delve properly into them tomorrow when back at work, I decided to give myself a weekend off this week and took some R&R, but will definitely post back if I get stuck further.

Thanks again
Post #1418136
« Prev Topic | Next Topic »

Add to briefcase 12»»

Permissions Expand / Collapse