Can You Use Indices with MySQL FIND_IN_SET?

Exploiting Indices with MySQL FIND_IN_SET or Equivalent

When utilizing FIND_IN_SET in MySQL, it's crucial to recognize its limitations in employing indices. A contrast with the equivalent id in (a, b) construct reveals that FIND_IN_SET exhibits an "ALL" type and lacks a defined key, resulting in inefficient performance when indices are available.

Overcoming the Limitation

While it's not possible to directly make FIND_IN_SET use indices, there is an alternative solution for utilizing indices in a similar context. This involves creating a prepared statement that accepts a comma-separated string as a parameter.

Prepared Statement Example

Consider the following prepared statement:

CREATE PROCEDURE get_data(IN comma_separated_ids TEXT)
BEGIN
  SELECT * FROM Foo WHERE id IN (comma_separated_ids);
END;

This prepared statement can be called with a string of comma-separated IDs as an argument. MySQL will automatically handle the conversion and perform an optimized query using indices (if available).

Explanation of Optimization

The id IN (a, b, c) construct is recognized by MySQL's optimizer as an equality condition on the primary key (id) column. Since the id column is indexed, the optimizer can utilize the index to retrieve the corresponding rows efficiently, resulting in the desired "range" type and efficient key usage.

Preventing SQL Injection Attacks

It's important to note that passing user-supplied data through prepared statements is a recommended practice to prevent SQL injection attacks. The database can securely handle the string conversions and prevent malicious input from affecting the query execution.

Conclusion

While FIND_IN_SET is not directly suitable for utilizing indices, the provided solution allows you to achieve the same functionality while leveraging indices for optimal performance. By following the described steps, you can create prepared statements that utilize indices effectively, improving query speed and maintaining data integrity.

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