Jinkun Liu created FLINK-39049:
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Summary: Introduce built-in functions `VARIANT_VALUE` and
`VARIANT_QUERY` to extract values from a variant
Key: FLINK-39049
URL: https://issues.apache.org/jira/browse/FLINK-39049
Project: Flink
Issue Type: Sub-task
Components: Table SQL / API
Reporter: Jinkun Liu
|SQL Function|Table Function|Description|
|VARIANT_VALUE(variant, path RETURNING type [ { NULL \| ERROR \| DEFAULT } ON
EMPTY ] [ { NULL \| ERROR \| DEFAULT } ON ERROR ])|VARIANT.variantValue(STRING
path [, type, onEmpty, defaultOnEmpty, onError, defaultOnError])|Extracts a
scalar as the given type from a variant.<br><br> <br><br>This method queries
the variant for the given path expression and returns the value if the value at
that path is scalar. Non-scalar values cannot be returned.<br><br> <br><br>For
empty path expressions or errors a behavior can be defined to either return
null, raise an error, or return a defined default value instead. When omitted,
the default is NULL ON EMPTY or NULL ON ERROR, respectively. The default value
may be a literal or an expression. If the default value itself raises an error,
it falls through to the error behavior for ON EMPTY, and raises an error for ON
ERROR.<br><br> <br><br>For path contains special characters such as spaces,
you can use ['property'] or ["property"] to select the specified property in a
parent object. Be sure to put single or double quotes around the property name.
When using VARIANT_VALUE in SQL, the path is a character parameter which is
already single quoted, so you have to escape the single quotes around property
name, such as JSON_VALUE('{"a b": "true"}', '$.[''a b'']').|
|VARIANT_QUERY(variant, path RETURNING type [ { WITHOUT \| WITH CONDITIONAL \|
WITH UNCONDITIONAL } [ ARRAY ] WRAPPER ] [ { NULL \| EMPTY ARRAY \| EMPTY
OBJECT \| ERROR } ON EMPTY ] [ { NULL \| EMPTY ARRAY \| EMPTY OBJECT \| ERROR }
ON ERROR ])|VARIANT.variantQuery(path, returnType [, variantQueryWrapper,
variantQueryOnEmptyOrError, variantQueryOnEmptyOrError ])|Extracts values as
type from a variant.<br><br> <br><br>The wrappingBehavior determines whether
the extracted value should be wrapped into an array, and whether to do so
unconditionally or only if the value itself isn’t an array already.<br><br>
<br><br>onEmpty and onError determine the behavior in case the path expression
is empty, or in case an error was raised, respectively. By default, in both
cases null is returned. Other choices are to use an empty array, an empty
object, or to raise an error.|
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