[HACKERS] Regarding B-Tree Lookup

I'm building some custom extension on top of postgres 9.6.1. As part of that, I would like to read Heap Tuple directly from my extension using Primary Key.

By default, postgres table index(B-Tree) its PrimaryKey(PK). So, i would like to get TID by doing a lookup into PK's B-Tree index. Using which i could read HeapTuple directly.

Please suggest me the easiest way to lookup into PK's B-Tree index for getting TIDs.

Suggesting a postgres extensions which does B-Tree lookup will also helps me.

Awaiting your response.

Thanks & Best Regards

- Mahi