What is equivalent of Long data type in PostgreSQL?

Should be a bigint

bigint 8 bytes large-range integer -9223372036854775808 to 9223372036854775807

From here: http://www.postgresql.org/docs/current/interactive/datatype-numeric.html

According to the docs it looks like bigint is your friend, with a range of -9223372036854775808 to 9223372036854775807.