Especially for large websites and portal applications, a high-performance and scalable search function is essential. Many CMS and store systems often already offer an out-of-the-box search function, which usually searches directly in the database (e.g. MySQL, PostgreSQL) for the desired information or relies on regular indexing. However, especially with large databases or complex content structures, this solution quickly reaches its limits.
This can be remedied by a dedicated search solution as a stand-alone application. The most common systems in the enterprise context are Apache Solr and Elasticsearch (ELK-Stack).