Union Dataset

The union dataset allows for rows from multiple datasets to be appended into a single dataset. Columns that match up between the datasets will be combined together. Row names are altered to reflect the dataset they came from and avoid having them merged together.

For example, the row names of to unified datasets will have the following format.

0.dataset index 0 row name
...
n.dataset index n row name

The union is done on the fly which means it is relatively rapid to unify even large datasets together.

Aside from the resulting row names, creating a union dataset is equivalent to the following SQL:

SELECT s1.* AS *, s2.* AS *
FROM (SELECT * FROM ds1 ) AS s1
OUTER JOIN (SELECT * FROM ds2) AS s2 ON false

Configuration

A new dataset of type union named <id> can be created as follows:

mldb.put("/v1/datasets/"+<id>, {
    "type": "union",
    "params": {
        "datasets": <ARRAY [ Dataset (read-only) ]>
    }
})

with the following key-value definitions for params: