Ramin Gharib created FLINK-41334:
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Summary: SQL Gateway JSON results and the JDBC driver cannot
return a UUID column
Key: FLINK-41334
URL: https://issues.apache.org/jira/browse/FLINK-41334
Project: Flink
Issue Type: Sub-task
Components: Formats (JSON, Avro, Parquet, ORC, SequenceFile), Table
SQL / Gateway, Table SQL / JDBC
Affects Versions: 2.4.0
Reporter: Ramin Gharib
The SQL Gateway serializes result rows with the {{json}} format converters, and
those have no {{UUID}} case. {{rowFormat=JSON}} is the default of the
fetch-results endpoint, and the JDBC driver always requests it. A query that
returns a {{UUID}} column therefore fails for REST clients and for JDBC.
{code:sql}
SELECT UUID_V4();
{code}
||Client||Row format||Result||
|SQL Client|{{PLAIN_TEXT}}|works, prints the canonical string|
|REST fetch-results without {{rowFormat}}|{{JSON}}, the
default|{{UnsupportedOperationException: Not support to parse type: UUID}}|
|JDBC driver|{{JSON}}|same error. The driver has no {{UUID}} mapping either|
I serialized a {{ResultInfo}} with one {{UUID}} column through
{{ResultInfoSerializer}} on 2.4-SNAPSHOT. {{PLAIN_TEXT}} round-trips and
{{JSON}} throws the error above.
h3. What is missing
# {{RowDataToJsonConverters}} and {{JsonToRowDataConverters}} in flink-json
have no {{UUID}} case. The gateway uses them in {{ResultInfoSerializer}} and
{{ResultInfoDeserializer}}.
# In the JDBC driver, {{ColumnInfo.fromLogicalType}} throws {{Not supported
type[UUID]}}, and {{FlinkResultSet.convertToJavaObject}} has no {{UUID}} case.
The gateway's own {{LogicalTypeJsonSerializer}} already handles {{UUID}}, so
the column metadata is fine.
h3. Proposal
* Write a {{UUID}} as its canonical string in both JSON converters and read it
back the same way. FLIP-604 already names the canonical string as the JSON
mapping. The {{json}} format uses the same converters and would accept {{UUID}}
columns too. That needs its own tests and docs.
* In the JDBC driver, report {{Types.OTHER}}, return {{java.util.UUID}} from
{{getObject}} and the canonical string from {{getString}}.
{{VARIANT}} has the same gap in {{ColumnInfo.fromLogicalType}}. That is out of
scope here.
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