Articles

External Article

The DELETE statement in SQL Server

Of the big four DML statements in SQL Server, the DELETE is the one least written about. This is odd considering the extra power conferred on the statement by the addition of the WITH common_table_expression; and the OUTPUT clause that essentially allows you to move data from one table to another in one statement.

2010-12-13

6,506 reads

Technical Article

Understanding and Controlling Parallel Query Processing in SQL Server

Data warehousing and general reporting applications tend to be CPU intensive because they need to read and process a large number of rows. To facilitate quick data processing for queries that touch a large amount of data, Microsoft SQL Server exploits the power of multiple logical processors to provide parallel query processing operations such as parallel scans. Through extensive testing, we have learned that, for most large queries that are executed in a parallel fashion, SQL Server can deliver linear or nearly linear response time speedup as the number of logical processors increases. However, some queries in high parallelism scenarios perform suboptimally. There are also some parallelism issues that can occur in a multi-user parallel query workload. This white paper describes parallel performance problems you might encounter when you run such queries and workloads, and it explains why these issues occur. In addition, it presents how data warehouse developers can detect these issues, and how they can work around them or mitigate them.

2010-12-10

4,645 reads

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Question of the Day

Creating a JSON Document III

I have this data in a table called dbo.NFLTeams 

TeamID  TeamName       City             YearEstablished
------  --------       ----             ---------------
1       Cowboys        Dallas           1960
2       Eagles         Philadelphia     1933
3       Packers        Green Bay        1919
4       Chiefs         Kansas City      1960
5       49ers          San Francisco    1946
6       Broncos        Denver           1960
7       Seahawks       Seattle          1976
8       Patriots       New England      1960
If I run this code, how many rows are returned? 
SELECT TOP 2 
  json_objectagg('Team' : TeamName)
FROM dbo.NFLTeams;

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