Effective management policies for datastore caches should provide good hit-ratios on a large number of workloads, operate in constant time, and maintain a small amount of metadata. In certain workloads, cache stability is an important metric, as limiting the number of cache updates can improve power consumption, increase the life expectancy of flash memories, and conserve network bandwidth in distributed settings. This paper introduces TinyCache, a compact table based management policy for datastore caches. TinyCache achieves similar hit ratio compared to the leading alternatives while operating in worst case constant time and only accessing a fixed sized memory word for each update. TinyCache encodes its metadata in a memory optimal manner and reduces the number of cache updates by up to X6 compared to state of the art.