Your results contain 17 solutions with the following criteria :

Databases
Solution Smile rating Users rating Popularity
MySQL MySQL 4.5 Smile 5.0 Visitors
46%   Popularity on the site
PostgreSQL PostgreSQL 4.3 Smile 4.6 Visitors
55%   Popularity on the site
MongoDB MongoDB 4.3 Smile 4.1 Visitors
68%   Popularity on the site
MariaDB MariaDB 4.2 Smile 4.5 Visitors
42%   Popularity on the site
Redis Redis 3.8 Smile 3.5 Visitors
14%   Popularity on the site
CouchBase CouchBase 3.5 Smile 4.4 Visitors
17%   Popularity on the site
Riak Riak 3.2 Smile 4.0 Visitors
14%   Popularity on the site
Cassandra Cassandra 3.2 Smile 3.3 Visitors
32%   Popularity on the site
Berkeley DB No rating No rating
7%   Popularity on the site
db4o No rating No rating
7%   Popularity on the site