I wonder if that one was meant to be controversial as it was the first item. My pedant sense started tingling immediately.
Search engines don't work like your standard RDBMS with SQL and whatnot. You can't just make a SQL query with a LIKE operator and just call it a day if you want modern, featureful searching.
But a search engine is absolutely a database. Lots of things are databases even if they aren't RDBMS and can't be queried with SQL.
Although, as a side note, I have seen some interesting projects that allow you to query things like file systems and operating systems using SQL, or at least syntax largely inspired by SQL.
Search engines don't work like your standard RDBMS with SQL and whatnot. You can't just make a SQL query with a LIKE operator and just call it a day if you want modern, featureful searching.
But a search engine is absolutely a database. Lots of things are databases even if they aren't RDBMS and can't be queried with SQL.
Although, as a side note, I have seen some interesting projects that allow you to query things like file systems and operating systems using SQL, or at least syntax largely inspired by SQL.