To do merge and groupby on host(CPU). (Ordered matching)

[AlexeyAB]

By using: thrust::merge() and thrust::reduce_by_key().

Now it is a header file that is not included and until has no affect.

Added functions:

• merge_by_key() - Merge hashes and values that already have been grouped/reduced by key.
• reduce_merged_by_key() - Reduce values that already has been merged by key

Parameters of templates:

• get_hashkeys - In merge_by_key() and reduce_merged_by_key() need use template parameter get_hashkeys - as true only once for one merging, for optimize. Because for each column merging and reducing hashkeys result (host_vec_keyhash_merged) are identical.
• T_hash_vec - must be thrust::host_vector
• T_val_vec - must be thrust::host_vector, where Type_field is a type of field :)

Postfixes in parameters of functions:

• _seg1 and _seg2 - vectors from different segments.

[antonmks]

Already done, thanks for the help !

Anton