how to reduce toast_tuple_threshold in PostgreSQL?

Question

OS: RHEL 7.2 PostgreSQL Version 9.6

I want toast to compress data. The average record length is around 500 Bytes in my tables. Although the columns show storage as extended, yet no compression is happening. Hence I want to modify toast_tuple_threshold to 500 bytes. Which file holds this value? And do we need to modify any other parameter?

Answer 1

I tried

ALTER TABLE tablename SET (TOAST_TUPLE_TARGET = 128);