Henrietta Domborvskaya takes a look at memory parameters in Postgres:
Ordinary PostgreSQL users often do not know that PostgreSQL configuration parameters exist, let alone what they are and what they mean. There is a good reason for such ignorance since, in real life, ordinary users don’t have any say in how these parameters are set. Configuration parameters are set not just for a database but for the whole instance, which may have multiple databases, so any individual user will get the same as others get. To be completely transparent, in some cases, the said ordinary users can specify some parameters just for their own uses, but let’s hold our horses for now.
There are over three hundred PostgreSQL configuration parameters, so no wonder that even experienced DBAs often do not know what each of these parameters does. That is perfectly fine; however, there is a widespread belief that somewhere, in the secret vaults of many consulting companies, there is a treasure chest of perfect PostgreSQL parameter settings.
Read on for more information about config parameters in general, followed by several memory-related parameters you can tweak and some guidance on where to begin with them.