Introduction
Businesses often use in-memory databases or key-value stores (caching layers) when applications require extremely high performance. However, in-memory databases incur a high total cost of ownership and have hard scalability limits, incurring reliability problems and restart delays when memory limits are exceeded. In-memory key-value stores share these limitations and introduce architectural complexity and network latency as well.
PHP, from the beginning of its time, is renowned (and criticized) for supporting integration with a lot of libraries, as well as with almost all the DB existing on the market. However, for some mysterious reasons, it did not support hierarchical databases on the globals.
In the previous parts (