Sql, Auxiliary table of numbers

The Why: Need for a Number Table

A numbers table, akin to a Swiss army knife, can be extremely versatile in a SQL environment. Sequence generation, data densification, filling in data gaps, set-based operations, and pagination are just a handful of applications. A key decision factor, before your fingers start dancing on the keyboard, is whether your task calls for a more temporary, on-the-fly sequence or a more permanent tally table.

The How: Performance Matters

In the world of SQL, performance is king and efficiency is queen. While generating a number table, the allure of a recursive CTE might be too strong due to its simplicity, yet for large sequences, it can come back to bite you in terms of efficiency. Instead, the use of a permanent Numbers table proves to be more performance-friendly for heavier tasks, leading to lower CPU usage, avoidance of unnecessary sorts, and more effective server resource management.

Let's Code: A Mighty Numbers Table

In an effort to avoid the performance pitfall associated with recursive CTEs, let's conjure up an optimized number table:

CREATE TABLE Numbers (Number INT PRIMARY KEY CLUSTERED);
WITH CTE AS (
  SELECT TOP (1000000) ROW_NUMBER() OVER (ORDER BY s1.[object_id]) AS [Number]
  FROM sys.all_objects AS s1 
  CROSS JOIN sys.all_objects AS s2
  --You'd think cross joins make terrible house guests (too many connections, right?), 
  --But here they behave quite well!
)
INSERT INTO Numbers ([Number])
SELECT [Number] FROM CTE;
-- Phew! Now that's a table worth writing home about!


Utilizing a CROSS JOIN helps us generate a large set and ROW_NUMBER() grants us the unique values we need. A clustered index on the primary key ties it all together for optimal performance.

Turbo Boost: Welcome SQL Server 2022’s GENERATE_SERIES

With the advent of SQL Server 2022 comes GENERATE_SERIES, a more advanced and high-efficiency function for number sequence creation:

SELECT Value AS Number
FROM GENERATE_SERIES(1, 1000) AS Sequence(Value);
-- “We can rebuild him. We have the technology - Better than he was before. Better, stronger, faster.”
-- It's SQL Server 2022, folks!


This method demands applause if you are dealing with larger-scale tasks or are sensitive to performance, as it's tuned specifically for SQL Server 2022.

Flexibility and Efficiency: Striking the Balance

Striving for flexibility while remaining resource-efficient is key. Be sure to tailor your number tables or user-defined functions (UDFs) to specific tasks. Having a properly indexed and sized number table can lift significant performance burdens, enhancing server wellbeing.

Testing: The Development Mantra

In a world where performance is king (and always will be), continuous performance testing cannot be stressed enough. Compare how different techniques perform in generating your number sequences. Be aware of CPU load and I/O operations which could affect server performance. Temporary tables, table variables or Common Table Expressions (CTEs) can vary in performance based on a variety of factors.

SCHEMABINDING: Shielding From Changes

When creating functions or views that return number sequences, look towards SCHEMABINDING to stead the ship. SCHEMABINDING binds the schema of the referenced objects, preventing structural changes that might break your function or view.

Caution: Protect against inefficient practices

Always guard your server against resource-draining practices. Beware of Halloween Protection issues as they can trigger high CPU, I/O operations, and unnecessary sorting. Always balance optimization and code clarity to protect your server and to ensure long-term maintainability.