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Posted to issues@calcite.apache.org by "Forward Xu (JIRA)" <ji...@apache.org> on 2019/03/05 05:57:00 UTC

[jira] [Assigned] (CALCITE-2892) Add the JSON_KEYS function

     [ https://issues.apache.org/jira/browse/CALCITE-2892?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Forward Xu reassigned CALCITE-2892:
-----------------------------------

    Assignee: Forward Xu

> Add the JSON_KEYS function
> --------------------------
>
>                 Key: CALCITE-2892
>                 URL: https://issues.apache.org/jira/browse/CALCITE-2892
>             Project: Calcite
>          Issue Type: New Feature
>            Reporter: Forward Xu
>            Assignee: Forward Xu
>            Priority: Major
>
> [{{JSON_KEYS(_{{json_doc}}_[, _{{path}}_])}}|https://dev.mysql.com/doc/refman/5.7/en/json-search-functions.html#function_json-keys]
> Returns the keys from the top-level value of a JSON object as a JSON array, or, if a _{{path}}_ argument is given, the top-level keys from the selected path. Returns {{NULL}} if any argument is {{NULL}}, the _{{json_doc}}_ argument is not an object, or _{{path}}_, if given, does not locate an object. An error occurs if the _{{json_doc}}_argument is not a valid JSON document or the _{{path}}_ argument is not a valid path expression or contains a {{*}} or {{**}} wildcard.
> The result array is empty if the selected object is empty. If the top-level value has nested subobjects, the return value does not include keys from those subobjects.
> Example SQL:
> {code:java}
> // code placeholder
> SELECT JSON_KEYS(v) AS c1
> ,JSON_KEYS(v, 'lax $.a') AS c2
> ,JSON_KEYS(v, '$.b') AS c3
> ,JSON_KEYS(v, 'strict $.a[0]') AS c4
> ,JSON_KEYS(v, 'strict $.a[1]') AS c5
> FROM (VALUES ('{"a": [10, true],"b": {"c": 30}}')) AS t(v)
> LIMIT 10;
> {code}
> Result:
> ||c1||c2||c3||c4||c5||
> |["a", "b"]|[NULL]|["c"]|[NULL]|[NULL]|



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