The first command we execute is nothing but a basic summary of the current memory state. For a test system with 2 GB of RAM running PostgreSQL, it would resemble this:
MemTotal: 2050908 kB MemFree: 840088 kB Buffers: 9288 kB Cached: 1102228 kB
This output is similar to what we would learn using the free command. The MemTotal row should speak for itself, as it is the total size of the memory in the system. The MemFree row is the total amount of completely unallocated system memory, including buffers or cache. The Buffers row in this context is mostly related to internal kernel bookkeeping, so we can ignore it. If we examine the value reported by the Cached row, we can see that over 1 GB of data is cached in memory.
The second ...
