How to find AMP number using Row-Hash value. I have gone through something in a blog. Below one is the link.
Here for the PI value 55 Row-Hash is 11110000111100001111000011110000. For this they said AMP no=4. How they derived it?
Question may be silly, but I am beginner to TD. Please help me in understanding this.
SELECT HASHROW(55) AS hr, HASHBUCKET(hr) AS hb, HASHAMP(hb);
The Hassh values is of 32 bit. HBN is the first 16/20 bits of hash value. Is there any significance of remaining bytes of hashvalue ? or these bits reserved for future enhancements ?
The first 16 or 20 bits are used to find the proper amp from the hash map, but the full 32 bit row hash is stored within the row, and is used in row retrieval.