Today we continue discussing the best practice from storage engineering:

620) When a new key is added, it may not impact existing keys but it does affect the overall space consumption of the listing depending on the size and number.

621) The keys can have as many fields as necessary. However, the lookups are faster when there are only a few keys to compare.

622) Key comparison can be partial or full. Partial keys are useful to match duplicates. The number of keys that share the same subkeys can be many. This form of comparison is very helpful to group entries.

623) Grouping of entries also help with entries that span groups based on sub keys. These work across groups

624) The number of entries may run to a large order but the prefix could be more inclusive of subkeys to narrow the search. This makes it efficient to run on these listings.

625) The number of entries also don’t matter to the number of keys in each entry as long as the prefix is using a small set of subkeys.

626) Listings are great to use when they are in a single location. However, they are often scoped to a parent container. If the parent containers are distributed, the listings tend to be multiple. In such cases the effort is repeated.

#codingexercise
Find paths in a matrix
int GetPaths(int x, int y)
{
    if (x <= 0 ||  y <= 0)
        return 1;

    return GetPaths(x - 1, y) +
               GetPaths(x - 1, y - 1) +
               GetPaths (x, y - 1); // for the three possible directions
}