Aggregating on postgres interval columns

^{Originally posted by **otonnesen** January 6, 2023}
Hi all,

I'm trying to perform an aggregation query on a table with an interval column, but I'm getting an error. I couldn't find any info on interval aggregations in the docs github issues. Am I just missing something obvious in the example below, or can intervals not be used in Hasura's built-in aggregation utilities?

### Context

Running Postgres 14.4 and Hasura 2.16.1.

Table:
```sql
create table test (id bigint, duration interval);
```
Query:
```gql
{
test_aggregate {
aggregate {
sum {
duration
}
}
nodes {
id
}
}
}
```
Error:
```json
{
"errors": [
{
"extensions": {
"code": "validation-failed",
"path": "$.selectionSet.test_aggregate.selectionSet.aggregate.selectionSet.sum.selectionSet.duration"
},
"message": "field 'duration' not found in type: 'test_sum_fields'"
}
]
}
```