VARCHAR vs. TEXT in MySQL: When Should I Use Which?

Distinctions Between VARCHAR and TEXT in MySQL

In MySQL, creating tables necessitates specifying column types. While VARCHAR requires a length specification, TEXT does not. Understanding the differences between these two data types is crucial.

Crucial Differences

• TEXT:

  • Fixed maximum size of 65535 characters
  • Requires 2 c bytes of disk space (c is string length)
  • Cannot be fully indexed (prefix length required)

• VARCHAR(M):

  • Variable maximum size of up to M characters (M can range from 1 to 65535)
  • Requires 1 c bytes (for M ≤ 255) or 2 c bytes (for 256 ≤ M ≤ 65535) of disk space
  • Can be indexed

Additional Details

• TEXT fields are constrained by a fixed length of 65535 characters, while VARCHAR fields offer flexibility by allowing variable lengths up to the specified maximum.
• TEXT fields cannot be indexed except for fulltext indexing, necessitating the use of VARCHAR for efficient searching.
• Selecting a VARCHAR type is appropriate when the maximum string length is known, thus avoiding potential issues with excessive storage usage.
• If the stored text exceeds 65535 characters, MEDIUMTEXT or LONGTEXT types become necessary. However, these types carry memory allocation concerns when retrieving data via certain programming languages.
• Proper input validation should always be performed to ensure data integrity and avoid potential security vulnerabilities.
• Both TEXT and VARCHAR provide space-efficient storage relative to their variable lengths. However, fixed-length data types such as CHAR offer improved performance when speed is a priority.

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