Melchizedek, who was he?

[OneEternalSonata]

In the LDS faith Melchizedek is known as a high priest and a just and holy man.

D&C 107:1-4~
1 THERE are, in the church, two priesthoods, namely, the Melchizedek and Aaronic, including the Levitical Priesthood.
2 Why the first is called the Melchizedek Priesthood is because Melchizedek was such a great high priest.
3 Before his day it was called the Holy Priesthood, after the Order of the Son of God.
4 But out of respect or reverence to the name of the Supreme Being, to avoid the too frequent repetition of his name, they, the church, in ancient days, called that priesthood after Melchizedek, or the Melchizedek Priesthood.

Also, Abraham paid tithes to him. From that, I personally infer that Melchizedek was Abraham's priesthood authority. However, where does he sit from Judaism's point of view? What oral traditions exist about him?