Expected behavior for updates between MIX

[kmaehashi]

Thinking of the following scenario:

1. Server received UPDATE request from client
2. Server starts MIX
3. get_diff done.
4. Server received UPDATE request from client
5. put_diff done.

For classifier, UPDATE request given in 4. will be lost (overwritten by 5.).
However, for recommender, it persists in sparse_matrix_storage that holds the original feature vectors.
What behavior should I expect in such case for each engine?

[kmaehashi]

+------------------+-----------------------------------+-----------------------------+
| Engine           | Algorithm                         | Behaviour                   |
+==================+===================================+=============================+
| Classifier       |  `nn`                             | Preserve                    |
|                  +-----------------------------------+-----------------------------+
|                  |  Others                           | Discard                     |
+------------------+-----------------------------------+-----------------------------+
| Regression       |  -                                | Discard                     |
+------------------+-----------------------------------+-----------------------------+
| Recommender      |  `nearest_neighbor_recommender`   | Preserve [^1]               |
|                  +-----------------------------------+-----------------------------+
|                  |  Others                           | Discard [^2]                |
+------------------+-----------------------------------+-----------------------------+
| Nearest Neighbor |  -                                | Preserve [^3]               |
+------------------+-----------------------------------+-----------------------------+
| Anomaly          |  `lof`                            | Discard [^2]                |
|                  +-----------------------------------+-----------------------------+
|                  |  `light_lof`                      | Preserve [^3]               |
+------------------+-----------------------------------+-----------------------------+
| Clustering       |  -                                | Preserve                    |
+------------------+-----------------------------------+-----------------------------+
| Burst            |  -                                | Discard                     |
+------------------+-----------------------------------+-----------------------------+
| Stat             |  -                                | Preserve                    |
+------------------+-----------------------------------+-----------------------------+
| Graph            |  -                                | Preserve                    |
+------------------+-----------------------------------+-----------------------------+
| Bandit           |  -                                | Discard                     |
+------------------+-----------------------------------+-----------------------------+

Footnotes

1. When adding new rows between MIX, the newly added row will be preserved. When overwriting existing rows between MIX, the modification will be discarded. ↩

[kmaehashi]

I've updated the table.