SQLite
SQLite is suitable for small to medium wikis with low to moderate traffic and is particularly advantageous for portable installations, such as those running from a USB stick, due to its single-file database structure that simplifies backups and migration. It does not require a separate database server, reducing administrative overhead and potential points of failure. However, SQLite does not scale beyond a single server, making it unsuitable for wikis that may grow to have many concurrent users or large amounts of content.