Druid Using multiple dimensions for a Dimension Extraction Function - druid

Question

Is it possible to use multiple dimensions for a dimension extraction function?
Something like:
{
"type": "extraction",
"dimension": ["dimension_1", "dimension_2"],
"outputName": "new_dimension",
"outputType": "STRING",
"extractionFn": {
"type": "javascript",
"function": "function(x, y){ // do sth with both x and y to return the result }"
}
}

Answer 1

I do not think this is possible. However, you can create something like that by first "merge" the 2 different dimensions using a virtualColumn, and then use an extraction function. You can then split the values again.
Example query (using https://github.com/level23/druid-client)
$client = new DruidClient([
"router_url" => "https://your.druid"
]);
// Build a groupBy query.
$builder = $client->query("hits")
->interval("now - 1 hour/now")
->select("os_name")
->select("browser")
->virtualColumn("concat(os_name, ';', browser)", "combined")
->sum("hits")
->select("combined", "coolBrowser", function (ExtractionBuilder $extractionBuilder) {
$extractionBuilder->javascript("function(t) { parts = t.split(';'); return parts[0] + ' with cool ' + parts[1] ; }");
})
->where("os_name", "!=", "")
->where("browser", "!=", "")
->orderBy("hits", "desc")
;
// Execute the query.
$response = $builder->groupBy();
Example result:
+--------+--------------------------------------------------+--------------------------+---------------------------+
| hits | coolBrowser | browser | os_name |
+--------+--------------------------------------------------+--------------------------+---------------------------+
| 418145 | Android with cool Chrome Mobile | Chrome Mobile | Android |
| 62937 | Windows 10 with cool Edge | Edge | Windows 10 |
| 27956 | Android with cool Samsung Browser | Samsung Browser | Android |
| 9460 | iOS with cool Safari | Safari | iOS |
+--------+--------------------------------------------------+--------------------------+---------------------------+
Raw native druid json query:
{
"queryType": "groupBy",
"dataSource": "hits",
"intervals": [
"2021-10-15T11:25:23.000Z/2021-10-15T12:25:23.000Z"
],
"dimensions": [
{
"type": "default",
"dimension": "os_name",
"outputType": "string",
"outputName": "os_name"
},
{
"type": "default",
"dimension": "browser",
"outputType": "string",
"outputName": "browser"
},
{
"type": "extraction",
"dimension": "combined",
"outputType": "string",
"outputName": "coolBrowser",
"extractionFn": {
"type": "javascript",
"function": "function(t) { parts = t.split(\";\"); return parts[0] + \" with cool \" + parts[1] ; }",
"injective": false
}
}
],
"granularity": "all",
"filter": {
"type": "and",
"fields": [
{
"type": "not",
"field": {
"type": "selector",
"dimension": "os_name",
"value": ""
}
},
{
"type": "not",
"field": {
"type": "selector",
"dimension": "browser",
"value": ""
}
}
]
},
"aggregations": [
{
"type": "longSum",
"name": "hits",
"fieldName": "hits"
}
],
"virtualColumns": [
{
"type": "expression",
"name": "combined",
"expression": "concat(os_name, ';', browser)",
"outputType": "string"
}
],
"context": {
"groupByStrategy": "v2"
},
"limitSpec": {
"type": "default",
"columns": [
{
"dimension": "hits",
"direction": "descending",
"dimensionOrder": "lexicographic"
}
]
}
}