Articles

External Article

Operator of the Week - Lazy Spool

Continuing to illuminate the depths of SQL Server's Query Optimizer, Fabiano shines a light on the sixth major Showplan Operator on his list: the Lazy Spool. What does the Lazy Spool do that's so special, how does the Query Optimizer use it, and why is it so Lazy? Fabiano Amorim explains all.

2010-06-28

2,774 reads

External Article

Making your SQL Server database changes backward compatible: Adding a new column

As multi-tier architectures grow over time, it is often challenging to coordinate those changes across the data, logic and presentation tiers. Unless planned and implemented carefully, an act as simple as adding a column to a table can grind all of the components of your application to a halt. While some of us have comfortable 12-hour maintenance windows every weekend, many of us are bound by service level agreements that are much more strict. So we must find ways to introduce fixes and new features with zero downtime, and without requiring every single component to be refactored at the same time.

2010-06-23

3,366 reads

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Question of the Day

Fun with JSON I

I have some data in a table:

CREATE TABLE #test_data
(
    id INT PRIMARY KEY,
    name VARCHAR(100),
    birth_date DATE
);

-- Step 2: Insert rows  
INSERT INTO #test_data
VALUES
(1, 'Olivia', '2025-01-05'),
(2, 'Emma', '2025-03-02'),
(3, 'Liam', '2025-11-15'),
(4, 'Noah', '2025-12-22');
If I run this query, how many rows are returned?
SELECT *
FROM OPENJSON(
     (
         SELECT t.* FROM #test_data AS t FOR JSON PATH
     )
             ) t;

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