If you want to change a configuration parameter that is classified as local, you must change it in every postgresql.conf file where you want that change to take effect. In most cases, this means making the change at the master and at every segment (primary and mirror). To set a parameter in all postgresql.conf files of a Greenplum system, you can use the gpconfig utility. For example:

$ gpconfig -c gp_vmem_protect_limit -v 4096MB

Then restart Greenplum Database to make the configuration changes effective:

$ gpstop -r