Realtime Compute for Apache Flink:JSON_TUPLE

Limits

The JSON_TUPLE function is supported only in Ververica Runtime (VVR) 3.0.0 and later.

Syntax

JSON_TUPLE(str, path1, path2 ..., pathN)     

Input parameters

Examples

• Test data

  Table 1. T1

  d(VARCHAR)	s(VARCHAR)
  {"qwe":"asd","qwe2":"asd2","qwe3":"asd3"}	qwe3
  {"qwe":"asd4","qwe2":"asd5","qwe3":"asd3"}	qwe2

• Test statement

  SELECT d, v 
  FROM T1, lateral table(JSON_TUPLE(d, 'qwe', s))
  AS T(v);   

• Test result

  d(VARCHAR)	v(VARCHAR)
  {"qwe":"asd","qwe2":"asd2","qwe3":"asd3"}	asd
  {"qwe":"asd","qwe2":"asd2","qwe3":"asd3"}	asd3
  {"qwe":"asd4","qwe2":"asd5","qwe3":"asd3"}	asd4
  {"qwe":"asd4","qwe2":"asd5","qwe3":"asd3"}	asd5

Change in NULL value handling behavior

Behavior comparison

Assume that you invoke the function in the query json_tuple(CAST(NULL AS STRING), 'a', 'b'), where the `str` input parameter is NULL.

SELECT * FROM (VALUES (1), (2)) AS v(x)
, LATERAL TABLE(
  json_tuple(CAST(NULL AS STRING), 'a', 'b')
) AS T;
-- Each input row returns two rows with NULL. Total: 4 rows — (1,null), (1,null), (2,null), (2,null)

• Before VVR 11.0 (legacy behavior)

  • Result: Four rows.

  • Content: Each row contains one NULL column.

• VVR 11.0 and later (new behavior)

  • Result: Zero rows (empty set).

  • Content: None.