I have read multiple online blogs, watched videos and still not clarified about 1. Actual difference between bg_writer and checkpointer. When I am querying update set, If bgwriter flushes dirty buffer to base every 200ms(bgwriter_delay), why would I need checkpointer to invoke bgwriter?
Same way, what happens for insert query?
1. How the flow works?
Dml-->wal_buffer-->also copied to shared_buffer--> commit-->flushed to pg_wal using wal writer -->checkpointer-->fsync to datapath-->bgwriter flushed to base.