Have you used database connection in your unit tests?

In a database management system (DBMS), the data types that are efficiently indexed include:

• Numeric types (integer, float) — enable fast comparison and range queries.
• String types (varchar, text) — especially with prefix or full-text indexes.
• Date and time — for quick searches over time ranges.
• Boolean values — although indexing may be less effective with low selectivity.
• Geospatial data — using spatial indexes like R-trees.

It is important to note that indexes are most effective when data has high selectivity, meaning queries using the index significantly reduce the number of records processed.

Example: an index on the email field in a user table speeds up searches for a specific email.