How Should I Store Gender Data in a Database for Optimal Size and Performance?

Storing Gender in a Database: Considerations for Size and Performance

When storing a user's gender in a database, it's important to balance storage space and performance efficiency. Three common scenarios include:

1. Integer (Int): This aligns with an enum in code, assigning numerical values (e.g., 1 = Male, 2 = Female). Ints require 4 bytes of storage.
2. Character (char(1)): This option allows for a single-character identifier (e.g., "m" for Male, "f" for Female). Char(1) requires 1 byte of storage, making it the most compact option.
3. Bit: MS SQL 2008 supports the bit datatype. As a boolean value, a bit can represent two possible states (True/False). However, it's important to consider an appropriate field name for this option.

The size and performance implications of these scenarios differ. According to an MSDN article, a bit field (1 bit) takes up 1 byte of space, while a char(1) takes up 2 bytes of space. Therefore, char(1) may be a slightly more space-efficient option for storing a single-character gender indicator.

However, ISO 5218 provides a standardized approach for storing gender. The standard recommends using a tinyint data type with a CHECK constraint or a lookup table. A tinyint is a 1-byte integer that can store values from -128 to 127. The CHECK constraint or lookup table would ensure that the values stored in the "Sex" column adhere to the standard's definitions.

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