I'm using Django with PostgreSQL but I need to use some App to handle thumbnails. There is an app very well rated called Sorl-Thumbnail
In the installation instructions says that I need to use a key value/caching system.
My doubt is: Can I use PostgreSQL database as cache or I will must to install memcached or redis?
I'm currently not using any caching mechanisms, the website is targeted for low traffic.
You can use the database cache backend, or even the FS cache backend. By "you can", I mean that "it will work". Just configure it normally for your django project and sorl-thumbnail will use it.
As per sorl-thumbnail documentation:
a cached database which requires no special installation to your normal Django setup besides installing a proper cache like memcached
But it won't be as awesome as memcached or redis.
(Also: why does sorl-thumbnail require this now ? It used to just check the FS to ensure that the thumbnail exists or else create it)