Type: integer
Default: 524288 (512kB)
Min: 65536 (64kB)
Max: 1073741823 (1073741823B)
Unit: B
Context: postmaster
Restart: true
Since: 15

A limit on how far ahead the server can look in the WAL, to find blocks to prefetch. If this value is specified without units, it is taken as bytes. The default is 512kB.