A having clause is a JSON object identifying which rows from a groupBy query should be returned, by specifying conditions on aggregated values.
It is essentially the equivalent of the HAVING clause in SQL.
Druid supports the following types of having clauses.
The simplest having clause is a numeric filter. Numeric filters can be used as the base filters for more complex boolean expressions of filters.
The equalTo filter will match rows with a specific aggregate value. The grammar for an equalTo
filter is as follows:
{ "type": "equalTo", "aggregation": <aggregate_metric>, "value": <numeric_value> }
This is the equivalent of HAVING <aggregate> = <value>
.
The greaterThan filter will match rows with aggregate values greater than the given value. The grammar for a greaterThan
filter is as follows:
{ "type": "greaterThan", "aggregation": <aggregate_metric>, "value": <numeric_value> }
This is the equivalent of HAVING <aggregate> > <value>
.
The lessThan filter will match rows with aggregate values less than the specified value. The grammar for a greaterThan
filter is as follows:
{ "type": "lessThan", "aggregation": <aggregate_metric>, "value": <numeric_value> }
This is the equivalent of HAVING <aggregate> < <value>
.
The grammar for an AND filter is as follows:
{ "type": "and", "havingSpecs": [<having clause>, <having clause>, ...] }
The having clauses in havingSpecs
can be any other having clause defined on this page.
The grammar for an OR filter is as follows:
{ "type": "or", "havingSpecs": [<having clause>, <having clause>, ...] }
The having clauses in havingSpecs
can be any other having clause defined on this page.
The grammar for a NOT filter is as follows:
{ "type": "not", "havingSpec": <having clause> }
The having clause specified at havingSpec
can be any other having clause defined on this page.