4. Postgres Administration - Postgres Architecture 

The Architecture of PostgreSQL
Postmaster
First Process to start
Validate the connection request and assign process
Maintain background processes
Utilities Processes
BG Writer : Write modified data to data files
Wal Writer : Write wal logs to wal file
Check pointer : Every 5 min or Max_wal_size is exceeded
Auto Vacuum : Vacuum operation on bloated tables
Stats Collector : Instance activities
Log Writer : Write errors in log file
Archiver : When enabled, it move the wal files to archive path
Buffers:
Shared Buffer : shared_buffer
Wal Buffer : Write ahead log / Transaction log. Wal_buffers
Clog Buffer
Work Mem
Maintenance
Work Mem
Temp