SELECT * or Explicit Column Lists: When is One Better for Database Query Performance?

*Database query performance: `SELECT ` is the best option with explicit column list**

In database queries, the efficiency of the SELECT statement is crucial. It is generally considered more efficient to select only necessary columns than to use SELECT * (retrieve all columns).

But if you need all the columns in the table, is it more efficient to use SELECT * or to list each column explicitly?

Technical Advantages of Explicit Column Lists

1. Index utilization:

   Explicit column lists allow SQL Server to potentially leverage existing indexes to retrieve data faster. This is because indexes are designed for specific columns, and it is more efficient to access the data by specifying those columns directly.

2. Mode Flexibility:

   Explicit column lists are more tolerant to schema changes. Code using SELECT * statements may break if new columns are added to the table in the future, while code using explicit column lists will not be affected.

*When to use `SELECT `**

Despite these technical advantages, there are situations where SELECT * still applies:

• Pure information query:

  For queries used for troubleshooting or data exploration, SELECT * is reasonable if all columns are needed to quickly view the table contents.

• Limited impact:

  If the table is small, the performance difference between SELECT * and an explicit column list is probably negligible. However, it is generally recommended to use explicit column lists to ensure the best performance in the long term.

Ultimately, whether to use SELECT * or specify explicit columns depends on the specific needs of your application. For performance-sensitive applications, it is highly recommended to explicitly list necessary columns to maximize efficiency and flexibility.

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