Especially with cloud hosting providers, were more memory gets expensive, I would recommend to go with native C/C++ applications like Postgres/MySQL/SphinxSearc

Especially with cloud hosting providers, were more memory gets expensive, I would recommend to go with native C/C++ applications like Postgres/MySQL/SphinxSearch/SQLite-FTS. (add Lucene based Solr and ElasticSearch to the list if memory is cheap)