What type of index would you use to implement full-text search in a database?

To implement full-text search in a database, full-text indexes are usually used. These indexes are optimized for fast searching through text data, taking into account words, their forms, and their placement.

For example, in relational databases such as MySQL or PostgreSQL, there are special types of indexes and functions for full-text search, which allow efficient document retrieval by keywords and phrases.

When using Java, external libraries and engines like Apache Lucene are often employed for full-text search, creating their own full-text indexes and providing powerful search capabilities.