An application and a plurality of types of storage in a distributed storage system are communicated with. A write instruction that includes a key-value pair that in turn includes a key and value is received from the application. The key-value pair is stored in a selected one of the plurality of types of storage where the selected type of storage is selected based at least in part on a size or access frequency of the key-value pair. A link to the stored key-value pair is stored, including by: generating a key hash based at least in part on the key from the key-value pair and selecting one of a plurality of rows in an extensible primary table in an index based at least in part on the key hash. If it is determined there is sufficient space, the link to the stored key-value pair is stored, in the selected row. If it is determined there is insufficient space, the key-value pair is stored in an overflow row in a secondary table.