ganeshashree opened a new pull request, #57957:
URL: https://github.com/apache/spark/pull/57957
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### What changes were proposed in this pull request?
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Add the ANSI SQL:2016 `JSON_QUERY` function (feature T828), which extracts
the JSON value located by a SQL/JSON path from a JSON input and returns it as
JSON text.
```
JSON_QUERY(jsonExpr, path
[ RETURNING type ]
[ (WITHOUT | WITH [CONDITIONAL | UNCONDITIONAL]) [ARRAY] WRAPPER ]
[ (KEEP | OMIT) QUOTES ]
[ (NULL | ERROR | EMPTY ARRAY | EMPTY OBJECT) ON EMPTY ]
[ (NULL | ERROR | EMPTY ARRAY | EMPTY OBJECT) ON ERROR ])
```
It is implemented as a parser-only production (no FunctionRegistry entry),
mirroring the merged JSON_VALUE (SPARK-58685) and reusing the JSON path
evaluator from JSON_TABLE (SPARK-58366). The matched object/array/scalar is
serialized verbatim; a scalar is emitted as JSON text under the default WITHOUT
ARRAY WRAPPER, OMIT QUOTES unquotes a scalar string, the array wrapper wraps
per the standard (CONDITIONAL wraps only a scalar), and ON EMPTY / ON ERROR
default to NULL. RETURNING is STRING-only for now (VARIANT deferred); paths are
wildcard-free.
Example (j = {"id":7,"name":"Ada","tags":["x","y"],"addr":{"city":"NYC"}}):
```
SELECT json_query(j, '$.addr'); -- {"city":"NYC"}
SELECT json_query(j, '$.tags'); -- ["x","y"]
SELECT json_query(j, '$.id'); -- 7 (scalar
as JSON text)
SELECT json_query(j, '$.name' OMIT QUOTES); -- Ada
SELECT json_query(j, '$.tags[0]' WITH ARRAY WRAPPER); -- ["x"]
SELECT json_query(j, '$.missing' EMPTY ARRAY ON EMPTY);-- []
SELECT json_query('not json', '$.a'); -- NULL (NULL ON
ERROR default)
```
Follow-ups (shared with JSON_VALUE, out of scope here): default-collation
rewrite of the result, whole-stage codegen, and cross-expression parse sharing
for sibling projections.
### Why are the changes needed?
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JSON_QUERY is the SQL-standard way to extract an object/array/scalar
fragment from JSON, supported by Oracle, SQL Server, PostgreSQL, Trino, Flink,
and others. Spark had no equivalent, forcing migrated queries onto
get_json_object, whose NULL/error semantics differ (it conflates "missing" and
"parse error", always returns STRING, and offers no wrapper/quotes control).
This is the natural follow-on to JSON_VALUE.
### Does this PR introduce _any_ user-facing change?
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Yes. It adds the new JSON_QUERY SQL function and its documentation, and adds
JSON_QUERY, WRAPPER, QUOTES, KEEP, OMIT, CONDITIONAL, UNCONDITIONAL, and OBJECT
as non-reserved keywords (usable as identifiers in both modes). No change to
existing behavior.
### How was this patch tested?
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- New JsonQuerySuite (end-to-end): object/array/scalar extraction, JSON
null, all wrapper modes, KEEP/OMIT QUOTES (incl. escapes), EMPTY ARRAY/OBJECT,
ON EMPTY/ON ERROR, malformed/trailing input, RETURNING VARCHAR/CHAR
normalization, direct-construction validation, and keyword-as-identifier.
- Golden files in json-functions.sql; regenerated keywords*.sql.out.
- ExpressionParserSuite for every clause spelling; SQLKeywordSuite;
SparkThrowableSuite; and TableIdentifierParserSuite / JsonExpressionsSuite for
regression.
### Was this patch authored or co-authored using generative AI tooling?
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Generated-by: Claude Code (Claude Opus 4.8)
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