Added asNumber to OrderByColumnSpec

[flowbehappy]

This commit make dimension can be sorted numerically(only "long" here) besides lexicographically. e.g

query:
...
"dimensions": [
    "id",
],
"limitSpec": {
    "type": "default",
    "limit": 20,
    "columns": [
        {
            "asNumber": true,
            "dimension": "id",
            "direction": "ASCENDING"
        }
    ]
},
...

result:
id  name    score
0   alias   90
1   bob     75
2   joe     60
11  flow    88
14  kevin   54

[drcrallen]

Please have an explicit type parameter here if at all possible, rather than Object

[nishantmonu51]

It will be great, if you can add unit test for this feature.
you can have a look at GroupByQueryRunnerTest for existing groupBy unit tests.

[metamx-bot]

Can one of the admins verify this patch?

[metamx-bot]

Can one of the admins verify this patch?

[flowbehappy]

@drcrallen @nishantmonu51 I added test case and did some code clean up. And sorry for taking so long.

[drcrallen]

Thanks @flowbehappy few more comments:

If a dimension is called "id" I would expect it to be a high cardinality dimension rather than just "default". Is "id" supposed to be relatively high cardinality in this case?

[flowbehappy]

@drcrallen Totally agree. I will generate another more real test data.

[fjy]

@cheddar @himanshug @xvrl any thoughts here? My biggest high level concern is that it only Longs are supported, but it is a useful feature.

[himanshug]

It does not seem too hard to make this feature complete by adding support for doubles as well.
We can use a regex here instead to detect if its a double value or long value or something else. Accordingly use Double.parseDouble(..) or Long.parseLong(..) .
And in the compare above add another case to handle Doubles.
Also, you can refactor this code a little bit by having a private method like
private Comparable getDimensionValue() {

}
and calling return getDimensionValue(dimList.get(0));

[gianm]

I believe this use case is addressed by #3270 through "dimensionOrder": "numeric".