a.k.a. Pitahaya or Strawberry Pear. Pitahaya is the Spainish name for the fruit. I was told there are some with yellow flesh and some are red. It seems the red ones are better. I was told the one they brought back is the red flesh type.
Further, I found it is not a free standing cactus, but a vining one. The plant may creep over the ground or climb onto trees or wooden poles using aerial roots. My search revealed that those who cultivate the cactus uses wooden poles for support. However, the house I am staying in was developed from a former rubber estate and prone to termite infestations. I was thus reluctant to plant it. My son-in-law came up with the idea of using plastic pipes and tying the growing cactus to the pipes.
So the next day I walked over to the nearby hardware shop and bought some plastic pipes. However, I made the mistake of purchasing the small 1" diameter poles, and I doubt the pipes would make a good free standing support for the cactus if it is partly buried in the ground. The maid, a Cambodian, got the briliant idea of leaning the pipes against a dividing wall in the garden. Below is a picture of the growing cactus, the pipes, and the dividing wall:
