Why does DESCRIBE EXTENDED in Kafka KSQL return error ShowColumns not supported?

Question

I have a simple KTABLE in KSQL called DIMAGE

When I run the following code

{
"ksql": "DESCRIBE EXTENDED DIMAGE ;"
}

I receive the following error

{
    "@type": "generic_error",
    "error_code": 40000,
    "message": "Statement type `io.confluent.ksql.parser.tree.ShowColumns' not supported for this resource",
    "stackTrace": []
}

I also receive a similar error message trying to describe a stream. I also receive the same error message if I remove the EXTENDED attribute.

Answer 1

You're using the wrong REST endpoint. If you use query endpoint query you'll get your error:

$ curl -s -X "POST" "http://localhost:8088/query" \
       -H "Content-Type: application/vnd.ksql.v1+json; charset=utf-8" \
       -d '{
    "ksql": "DESCRIBE EXTENDED COMPUTER_T;"
  }'
{"@type":"generic_error","error_code":40000,"message":"Statement type `io.confluent.ksql.parser.tree.ShowColumns' not supported for this resource","stackTrace":[]}⏎

If you use the statement endpoint ksql it works fine:

$ curl -s -X "POST" "http://localhost:8088/ksql" \
       -H "Content-Type: application/vnd.ksql.v1+json; charset=utf-8" \
       -d '{
    "ksql": "DESCRIBE EXTENDED COMPUTER_T;"
  }'|jq '.'
[
  {
    "@type": "sourceDescription",
    "statementText": "DESCRIBE EXTENDED COMPUTER_T;",
    "sourceDescription": {
      "name": "COMPUTER_T",
      "readQueries": [
        {
          "sinks": [
            "COMP_WATCH_BY_EMP_ID_T"
          ],
          "id": "CTAS_COMP_WATCH_BY_EMP_ID_T_0",
[...]

I've logged #2362 so that we can improve the UX of this.