Unwind and alias used together in an OrientDB SQL query - sql

Question

Using OrientDB 2.2.16 and given the following data imported in a document database:
{
"teams": [
{
"name": "McLaren F1 Team",
"nationality": "british",
"headquarters": {
"city": "Woking",
"country": "England"
},
"drivers": [
{
"name": "Fernando Alonso",
"nationality": "Spanish",
"yearOfBirth": "1980"
},
{
"name": "Jenson Button",
"nationality": "British",
"yearOfBirth": "1980"
}
]
},
{
"name": "Scuderia Ferrari",
"nationality": "italian",
"headquarters": {
"city": "Maranello",
"country": "Italy"
},
"drivers": [
{
"name": "Sebastian Vettel",
"nationality": "German",
"yearOfBirth": "1987"
},
{
"name": "Kimi Raikkonen",
"nationality": "Finnish",
"yearOfBirth": "1979"
}
]
}
]
}
Using unwind, I want to find the query returning the names of all the drivers. To be exact, the result has to be a list of documents where each document contains the name of a driver in a property called "name".
My (not working) attempts:
SELECT drivers.name FROM Teams unwind drivers
It returns almost what I expect, but the name is placed under a property called "drivers".
SELECT drivers.name AS name FROM Teams unwind drivers
Fails totally, there's no unwind at all.
SELECT drivers.name AS name FROM Teams unwind name
This works, but it's kind of a bug actually because the alias applies to drivers, not name, and that's why the unwind works.

Answer 1

A little background on how the query is elaborated:
Teams data is fetched from the storage
each record is filtered (no filtering in this case, because you have no WHERE condition)
for each source record, the engine calculates the projections and creates a new document containing the projection values bound to aliases
In your case, at this step you have two records:
query 1: the default alias for drivers.name in v 2.2 is drivers (in v 3.0 this will change, the default alias will be drivers.name)
| drivers |
+-----------------------------------------+
| ["Fernando Alonso", "Jenson Button" ] |
| ["Sebastian Vettel", "Kimi Raikkonen" ] |
query 2 and 3: in this case the alias is name, you are defining it explicitly
| name |
+-----------------------------------------+
| ["Fernando Alonso", "Jenson Button" ] |
| ["Sebastian Vettel", "Kimi Raikkonen" ] |
the UNWIND is calculated on the result of step 3. The alias of the result is the same as the previous step
Query 1 unwinds drivers as expected, but the alias remains drivers
Query 2 tries to unwind drivers but it doesn't find it obviously, this is why it fails
Query 3 unwinds name as expected
As a conclusion: this is the expected behavior