BigInt(20) vs. Int(20) in MySQL: What's the Real Difference in Storage and Value Range?

Delving into the Nuances of MySQL Numeric Types: BigInt(20) vs. Int(20)

In the realm of database management, understanding the nature of numeric data types is crucial. In MySQL, the distinction between BigInt, MediumInt, and Int can be a source of perplexity, particularly regarding their perceived relation to storage capacity.

Unveiling the Myth: Size Limitation

Contrary to popular belief, the (20) suffix in Int(20) and BigInt(20) does not indicate a size restriction. Rather, it serves as a mere hint for display width, having no bearing on storage requirements or accepted value ranges.

The Essence of BigInt and Int

Fundamentally, BigInt is an 8-byte signed integer, while Int is a 4-byte signed integer. Their respective capacities determine the number of distinct values they can represent: 2^64 for BigInt and 2^32 for Int.

Addressing the Confusion

The common misconception that Int(20) implies a size limit stems from a misunderstanding of how MySQL handles numeric types. Unlike Char(20), which specifies a fixed length regardless of the actual data stored, Int(20) does not affect the underlying storage or value range.

Practical Implications

In practice, the (20) specification only influences the ZEROFILL display option. By enabling ZEROFILL, the value will be zero-padded to the specified width. For instance, an Int(20) with the value 1234 displayed with ZEROFILL would appear as '00000000000000001234'.

Conclusion

Grasping the fundamental differences between BigInt(20) and Int(20) is critical for optimizing database design in MySQL. By dispelling the myth of size limitation and clarifying their true nature, database administrators can make informed choices when selecting numeric data types to meet specific business requirements.

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