Several types of indexes can be used, depending on the specific needs of your email marketing database:
Primary Index: Usually the primary key of the table, ensuring each record can be uniquely identified. Secondary Index: Created to improve the performance of queries on non-primary key columns. Composite Index: Comprises multiple columns, useful for complex queries involving multiple fields. Full-Text Index: Useful for text-heavy fields like email content or subject lines, aiding in quick text searches.