Search results matching tags 'Administration', 'Developer', and 'Internals'

Squishy Limits in SQL Server Express Edition

KKline — Thu, 28 Mar 2013 12:19:00 GMT

It's an old story you've probably heard before. Provide a free version of your software product with strict limitations on performance or other specific capabilities so that folks can give it a try without risk, while you minimize the chance of cannibalizing sales of your commercial products. Microsoft has take this strategy with SQL Server Express Edition, not only to increase adoption in the student market but also to counter the threat of open-source (i.e. free) relational databases like MySQL for entry-level applications.

One such limitation of SQL Server Express Edition is that it supports no more than 1GB of RAM for the instance. Of course, you could have many Express Edition instances on a single Windows server, each with its own 1GB of RAM.

But what does that metric of 1GB of RAM actually mean? The key thing to remember is that the restriction is for buffer cache. Since SQL Server has many other caches, even when not counting the plan cache, there are plenty of other caches within SQL Server. (Run a query against sys.dm_os_memory_clerks if you'd like to see some of the others). Because only the buffer cache has the strict 1GB limitation, you can actually watch SQL Server Express Edition's memory working set size grow to around 1.4-1.5GB due to the other memory caches at play.

Pawel Potasinski, a SQL Server MVP from Poland (Twitter | Blog), once posted an interesting repro for this behavior:

-- Assess amount of databases resident in buffer cache

SELECT
 CASE
 WHEN database_id = 32767 THEN 'mssqlsystemresource'
 ELSE DB_NAME(database_id)
 END AS [Database],
 CONVERT(numeric(38,2),(8.0 / 1024) * COUNT(*)) AS [MB in buffer cache] 
FROM sys.dm_os_buffer_descriptors 
GROUP BY database_id 
ORDER BY 2 DESC; 
GO

-- Assess amount of tables resident in buffer cache
SELECT
 QUOTENAME(OBJECT_SCHEMA_NAME(p.object_id)) + '.' +
 QUOTENAME(OBJECT_NAME(p.object_id)) AS [Object],
 CONVERT(numeric(38,2),(8.0 / 1024) * COUNT(*)) AS [MB In buffer cache] 
FROM sys.dm_os_buffer_descriptors AS d 
 INNER JOIN sys.allocation_units AS u ON d.allocation_unit_id = u.allocation_unit_id 
 INNER JOIN sys.partitions AS p ON (u.type IN (1,3) AND u.container_id = p.hobt_id) OR (u.type = 2 AND u.container_id = p.partition_id) 
WHERE d.database_id = DB_ID() 
GROUP BY QUOTENAME(OBJECT_SCHEMA_NAME(p.object_id)) + '.' + QUOTENAME(OBJECT_NAME(p.object_id))
ORDER BY [Object] DESC;
GO

-- Fill up Express Edition's buffer allocation
IF OBJECT_ID(N'dbo.test', N'U') IS NOT NULL
 DROP TABLE dbo.test;
GO

CREATE TABLE dbo.test (col_a char(8000));
GO

INSERT INTO dbo.test (col_a)
 SELECT REPLICATE('col_a', 8000)
 FROM sys.all_objects 
 WHERE is_ms_shipped = 1;

CHECKPOINT; 
GO 100

The bottom line for the hard memory limit of SQL Server Express Edition is "Yes, it's limited. But it's a squishy limit. Not a hard limit."

Although your mileage may vary, I'd bet a dollar that you'll find more than 1GB in the active working set for your instance of SQL Server Express Edition. I am curious, however, if you're seeing much variation between versions and even service packs of SQL Server? Let me know if you try this out on more than one version and/or service pack level of SQL Server. Did it change much between versions? Let me know!

Enjoy,

-Kevin

-Follow me on Twitter!

Google Author

Learn More About SQL Server IO and Query Tuning in These Webcasts

KKline — Fri, 14 Dec 2012 18:50:00 GMT

I'm doing two new webcasts next week on Wednesday, December 19th, one in the morning and the other after lunch.

SSDs are a Game Changer for SQL Server Storage

No, session is not exclusively about SSDs. But this is my first session on IO and storage tuning that emphasizes SSDs over hard disks. As Bob Dylan said "Times, they are a'changin'". This session on Wednesday, December 19th at 11:30 AM EST, sponsored by Astute Networks, takes you through all of the basics of storage and IO tuning, regardless of the underlying storage technology. I'll show you how SQL Server handles storage structures, how to identify IO activity on Windows and SQL Server, and best practices for minimizing IO bottlenecks. Register now for: Storage IO Best Practices for SQL Server and a New Approach to Solving Application Performance Issues.

Write Better SQL Queries

The next webcast on Wednesday, December 19th at 2 PM EST, is with me, Aaron Bertrand (Twitter | Blog) and SQLCruise Impresario & Microsoft MVP Tim Ford (Twitter | Blog) as we take you through the query tuning process, discussing important DMVs to use during query tuning, as well as demonstrating several essential query tuning techniques that every SQL developer should know. Not only are we presenting an hour of top quality technical content, we’ll also be giving away some cool prizes, including the grand prize of a paid registration for the upcoming SQLCruise Miami, a $1,395 value! Register now for: SQL Server Query Tuning Best Practices, Hosted by Kevin Kline and Aaron Bertrand with special guest Tim Ford

I hope to see you at both of these sessions next week! Best regards,

-Kev

-Follow me on Twitter!

How Do You SKU?

KKline — Wed, 30 Mar 2011 14:49:00 GMT

I’d like your opinion here.

Follow my logic here for a moment as I walk through a couple rhetorical questions. Have you ever had a friend developed an application entirely on SQL Server Developer Edition? (Not that YOU would ever do such a thing, but maybe you know someone who has. Right?) And has your friend’s IT department actually deployed said application only to discover that they’re only licensed for Standard Edition in their production environment? And then was your friend’s IT management team is horrified to learn that they’ve either got to go through the very expensive process of extracting all of the Enterprise and/or Datacenter Edition features for the production application in order to remain in compliance, upgrade to the more expensive SKU licenses, or risk a potential future audit?

I’m not saying that this has happened to any of us. We’re too smart for that, after all. But have you ever known anyone who’s had this experience?

Having worked with a lot of customers another commercial RDBMS platforms (which I’ll euphemistically call “SEER” from Redforest City and “IB4” from Upstate City), I can tell you that auditing is a fun and exciting way for those platform vendors to make a LOT of money. This is especially true because a production application, once successfully deployed, tends to be too valuable to disable or otherwise compromise because high-end features slipped in to the development cycle even though the production environment only a “standard edition” SKU in place. Ouch! Talk about being caught between a rock and a hard place. Now, keep in mind that this is a strategy used by SEER and not by Microsoft. But Microsoft could implement the same sort of licensing audits if they wanted to. (Please leave a comment here if you have ever been audited. I’d love to hear your experiences, at least as much as NDA’s allow).

So if you use SQL Server Developer Edition (DE), of any version, would you like to see a feature that enables you to run DE not in its default “full featured mode” but at another SKU level, such as good ol’ Standard Edition? I know I would.

If you’re on the same page as I am, there are a number of suggestions logged on Connect about this very feature! Make your voice heard! Check out:

https://connect.microsoft.com/SQLServer/feedback/details/496380/enable-sql-developer-edition-to-target-specific-sql-version

Of course, the more skeptical reader might say “Hey, that’s their tough luck. Developers should know the difference in the SKU licensing options and feature sets of whatever SKU they’re developing on compared to what they’ll deploy on.” And I wouldn’t fault you for saying so.

But I would go on to point out that much of Microsoft’s success in enterprise IT settings can be traced back to their very strong relationship with developers. And anything that Microsoft can do to empower developers to save time, money, and resources during the development phase of an IT project in turn energizes that relationship between developer and Microsoft.

It also makes the life of the DBA that much easier, because they don’t need to imply that those cowboys on the development team went off half-cocked again. So what’s your opinion? Should SQL Server Developer Edition include a feature that sets the SKU-level of the database engine?

Join Me May 19th for 24 Hours of PASS

KKline — Mon, 26 Apr 2010 14:16:00 GMT

Join Us for 24 Hours of SQL Server Training

(with a special focus on SQL Server 2008 R2)

Did I mention that your Cohorts in Crime (that be me and Brent Ozar) are presenting?!?

The FREE 24 Hours of PASS event is bringing an exceptional lineup of SQL Server and BI experts to your computer starting at 12:00 GMT (UTC) on May 19.

Get an in-depth look at the hottest SQL Server and BI topics, including (but not limited to!) - the new SQL Server 2008 R2, with its business intelligence and data management innovations, and much more.

When does it start? 12:00 GMT (UTC):

New York: 08:00
Chicago: 07:00
San Francisco: 05:00
London: 13:00
Paris: 14:00
Moscow: 16:00
Mumbai: 17:30
Singapore: 20:00
Sydney: 22:00

The roster of phenomenal speakers features many MVPs and top-rated presenters, including Adam Machanic, Andy Leonard, Brad McGehee, Brent Ozar, Brian Knight, Chuck Heinzelman, Dean Richards, Don Kiely, Don Vilen, Donald Farmer, Glenn Berry, Greg Low, Jacob Sebastian, Jessica Moss, Kevin Cox, Kevin Kline, Louis Davidson, Maciej Pilecki, Peter Myers, Peter Ward, Rushabh Mehta, Sean McCown, Simon Sabin, Thomas Grosher.

Check out all the great SQL Server sessions you can attend for FREE. Share this information with a friend or colleague.

PASS is looking forward to having you join us all for this exceptional event. Please contact us at 24hrs@sqlpass.org with any questions. You can also find lots of general details at http://www.sqlpass.org/24hours/2010/.