To know more : https://github.com/citusdata/cstore_fdw/issues/193
Installation Steps:
-  Open Terminal using Spotlight search by pressing  
<command+space>.
Type terminal and hitEnterkey. -  Now, run 
ruby -e “$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install)” < /dev/null 2> /dev/null -  Install cstore_fdw using brew
brew instalIcstore_fdw 
cstore_fdw is ready to use now!