Sorting on stringLast aggregated fields doesn't seem to work

[vinpai]

Please provide a detailed title (e.g. "Broker crashes when using TopN query with Bound filter" instead of just "Broker crashes").

While using the limitSpec in groupBy queries, if we sort on stringLast aggregated fields, the final result isn't sorted.

Affected Version

0.14.2

Description

Based on the ingestion_spec mentioned here - https://druid.apache.org/docs/latest/tutorials/tutorial-ingestion-spec.html

If I have a query like below, it doesn't seem to sort the results. However, if the same field is added in the dimensions list, the results are sorted. However, in my use case I need the sorting on the stringLast value.

Another thing I noticed was if the sorting was done on one of the metrics using longLast aggregation, then that seems to work.

{
"dataSource": {
"type": "table",
"name": "ingestion-tutorial"
},
"queryType": "groupBy",
"intervals": [
"2019-07-23T23:31:40.737/2019-07-24T23:31:40.737"
],
"granularity": "all",
"limitSpec": {
"type": "default",
"columns": [
{
"dimension": "protocol",
"direction": "ascending",
"dimensionOrder": "alphanumeric"
}
],
"limit": 50
},
"dimensions": [
{
"type": "default",
"dimension": "srcIp",
"outputName": "srcIp"
},
{
"type": "default",
"dimension": "dstIp",
"outputName": "dstIp"
}
],
"aggregations": [
{
"type": "stringLast",
"name": "protocol",
"fieldName": "protocol"
}
]
}

Please include as much detailed information about the problem as possible.

• Cluster size
  Single server

• Configurations in use

• Steps to reproduce the problem

• The error message or stack traces encountered. Providing more context, such as nearby log messages or even entire logs, can be helpful.

• Any debugging that you have already done

[stale]

This issue has been marked as stale due to 280 days of inactivity. It will be closed in 4 weeks if no further activity occurs. If this issue is still relevant, please simply write any comment. Even if closed, you can still revive the issue at any time or discuss it on the dev@druid.apache.org list. Thank you for your contributions.

[stale]

This issue has been closed due to lack of activity. If you think that is incorrect, or the issue requires additional review, you can revive the issue at any time.