Note: At present, this section is just taken from PostgreSQL documentation and is subject to revision for Postgres-XC.
   SPI_getnspname returns a copy of the name of
   the namespace that the specified Relation
   belongs to. This is equivalent to the relation's schema. You should
   pfree the return value of this function when
   you are finished with it.
  
Note: At present, this section is just taken from PostgreSQL documentation and is subject to revision for Postgres-XC.
input relation