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Posted to issues@calcite.apache.org by "Forward Xu (JIRA)" <ji...@apache.org> on 2019/02/26 04:30:00 UTC
[jira] [Assigned] (CALCITE-2808) Add the JSON_LENGTH function
[ https://issues.apache.org/jira/browse/CALCITE-2808?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Forward Xu reassigned CALCITE-2808:
-----------------------------------
Assignee: Forward Xu
> Add the JSON_LENGTH function
> -----------------------------
>
> Key: CALCITE-2808
> URL: https://issues.apache.org/jira/browse/CALCITE-2808
> Project: Calcite
> Issue Type: Sub-task
> Reporter: Forward Xu
> Assignee: Forward Xu
> Priority: Major
>
> {{JSON_LENGTH(*json_doc*[, *path*])}}
> Returns the length of a JSON document, or, if a _path_ argument is given, the length of the value within the document identified by the path. Returns {{NULL}} if any argument is {{NULL}} or the _path_ argument does not identify a value in the document. 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 length of a document is determined as follows:
> * The length of a scalar is 1.
> * The length of an array is the number of array elements.
> * The length of an object is the number of object members.
> * The length does not count the length of nested arrays or objects.
> SELECT JSON_LENGTH('[1, 2, \\{"a": 3}]');
> +---------------------------------+
> |JSON_LENGTH('[1, 2, \\{"a": 3}]')|
> +---------------------------------+
> | 3|
> +---------------------------------+
> SELECT JSON_LENGTH('\{"a": 1, "b": {"c": 30}}');
> +-----------------------------------------+
> |JSON_LENGTH('\{"a": 1, "b": {"c": 30}}')|
> +-----------------------------------------+
> | 2|
> +-----------------------------------------+
> SELECT JSON_LENGTH('\{"a": 1, "b": {"c": 30}}', '$.b');
> +------------------------------------------------+
> |JSON_LENGTH('\{"a": 1, "b": {"c": 30}}', '$.b')|
> +------------------------------------------------+
> | 1|
> +------------------------------------------------+
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