Re: Question on Structuring Product Attributes

>> [only one index is needed and there is nothing to prevent an SQL parser being smart enough to realise this]
Marvelous. Identify which SQL does that (post evidence). <<

Mr. Hann can tell me if my memory is correct, but I think Ingres has something like 17 kinds of indexes and it did index optimization, picking the right one for a particular data distribution and merging or removing redundant ones. MS SQL Server has the INCLUDE option, which says to carry extra columns but not use them in the indexing process. This lets you get a cheap covering index.

Hashing algorithms work better with more columns (few collisions), so they will replace a shorter list of columns with a longer one in the hash.

Informix lets you create an index on a search condition for a multitable  join. This is not a VIEW, but pointers to the rows involved. Received on Wed Oct 19 2011 - 04:53:04 CEST