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James Serra's Blog

James is currently a Senior Business Intelligence Architect/Developer and has over 20 years of IT experience. James started his career as a software developer, then became a DBA 12 years ago, and for the last five years he has been working extensively with Business Intelligence using the SQL Server BI stack (SSAS, SSRS, and SSIS). James has been at times a permanent employee, consultant, contractor, and owner of his own business. All these experiences along with continuous learning has helped James to develop many successful data warehouse and BI projects. James has earned the MCITP Business Developer 2008, MCITP Database Administrator 2008, and MCITP Database Developer 2008, and has a Bachelor of Science degree in Computer Engineering. His blog is at .

Archives: November 2011

Buffer Size in SSIS

Behind the scenes in SSIS, the data flow engine uses a buffer-oriented architecture to efficiently load and manipulate datasets in memory.  The benefit of this in-memory processing is that you do not need to physically copy and stage data at each step of the data integration.  Rather, the data flow… Read more

4 comments, 4,265 reads

Posted in James Serra's Blog on 30 November 2011

Role-playing Dimensions

Dimensions are often recycled for multiple purposes within the same database.  For instance, a “Date” dimension can be used for “Date of Sale”, as well as “Date of Delivery”, or “Date of Hire”.  This is often referred to as a “role-playing dimension”.

Basically, if the same dimension is used more… Read more

1 comments, 2,654 reads

Posted in James Serra's Blog on 28 November 2011

Conformed dimensions

A conformed dimension is a dimension that has the same meaning to every fact with which it relates.  Conformed dimensions allow facts and measures to be categorized and described in the same way across multiple facts and/or data marts, ensuring consistent reporting across the enterprise.

A conformed dimension can exist… Read more

0 comments, 747 reads

Posted in James Serra's Blog on 21 November 2011

Reference Dimensions

A reference dimension occurs when the key column for the dimension is joined indirectly to the fact table through a key in another dimension table.  This results in a snowflake schema design.

The following figure shows one fact table named InternetSales, and two dimension tables called Customer (regular or… Read more

1 comments, 606 reads

Posted in James Serra's Blog on 18 November 2011

SQL Server 2012 RC0 is here!

SQL Server 2012 RC0 (Release Candidate 0), formerly known as SQL Server Denali, is now available for download.  SQL Server 2012 RC0 is the first release which is feature complete.

This was unexpected as no one gave any hints that it was coming.  Reminds me of The new phonebook’s here!. Read more

1 comments, 598 reads

Posted in James Serra's Blog on 17 November 2011

Degenerate Dimensions

Degenerate dimensions, also called fact dimensions, are standard dimensions that are constructed from attribute columns in fact tables instead of from attribute columns in dimension tables.  This is because useful dimensional data is sometimes stored in a fact table to reduce duplication, especially when you have a very large fact… Read more

1 comments, 2,026 reads

Posted in James Serra's Blog on 16 November 2011

Many-to-Many Dimensions

In SSAS, data structures do not always conform to the snowflake or star schema model where one fact is associated with a single dimension member.  For example, consider the example of financial transactions in accounts that can have one or more customers. This can be modeled as:

The relationship between… Read more

1 comments, 751 reads

Posted in James Serra's Blog on 14 November 2011

Parallel execution in SSIS

Parallel execution in SSIS improves performance on computers that have multiple physical or logical processors.  To support parallel execution of different tasks in a package, SSIS uses two properties: MaxConcurrentExecutables and EngineThreads.  If you are like me, you probably did not even know about these two properties, and therefore… Read more

3 comments, 2,821 reads

Posted in James Serra's Blog on 11 November 2011

Why does my SSIS package run slower in BIDS than DTEXEC?

If you have been creating SSIS packages in Business Intelligence Development Studio (BIDS) for any length of time, you have likely noticed that SSIS packages run slower in BIDS as opposed to running them in a SQL Server agent job (which uses the command prompt utility DTEXEC) or when in… Read more

0 comments, 669 reads

Posted in James Serra's Blog on 9 November 2011

SQL Server 2012: New Certifications

As a follow-up to my post SQL Server “Denali”: New Certifications, the seven exams for SQL Server 2012 are:

  • Querying Microsoft SQL Server (70-461) [BI and DBA]
  • Administering a Microsoft SQL Server 2012 Database (70-462) [DBA]
  • Building Data Warehouses with Microsoft SQL Server 2012 (70-463) [BI]
  • Developing a Microsoft SQL…

Read more

7 comments, 2,272 reads

Posted in James Serra's Blog on 7 November 2011

What is SQL PASS?

A few weeks ago I asked a colleague, who is a DBA, if he was going to the SQL PASS Summit.  He had no idea what PASS was.  It then occurred to me that there are probably thousands of DBAs, BI developers, DW architects, etc, who do not know about… Read more

0 comments, 508 reads

Posted in James Serra's Blog on 4 November 2011

Salaried employee vs contractor

Are you a salaried employee looking to switch to a W-2 or 1099 contractor? (For an explanation of W-2 and 1099, click Consultants: 1099 or W-2?)  If so, what hourly pay rate would you need to at least match your salary?

When trying to decide the equivalent pay between being… Read more

0 comments, 1,707 reads

Posted in James Serra's Blog on 2 November 2011