Q: How do I size the bucket_count value for SQL Server 2014's In-Memory OLTP hash indexes?
A: SQL Server 2014 has indexes used for point lookups of individual rows. Microsoft recommends that you size them at 1x to 2x the number for rows that you expect to have in the table.
If you don't know how many rows will be in the table, it's better to make the bucket_count value higher than you think you might need. Too small a value will reduce performance. With the initial release you cannot resize the bucket_count value without dropping and recreating the index.