[
https://issues.apache.org/jira/browse/CALCITE-2892?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16808291#comment-16808291
]
Hongze Zhang commented on CALCITE-2892:
---------------------------------------
Thank you for taking this, [~x1q1j1]!
So far the PR looks good to me, and I've added some minor changes, please take
a look at the
[branch|https://github.com/zhztheplayer/calcite/commit/939cd9417bab48ec1b571caefda4c15df31d43b8].
The minor changes list:
* reformatted reserved and non-reserved keyword list a bit;
* simplified some unparse method on JSON operators;
* simplified first several code lines from method SqlFunctions#jsonKeys.
> Add the JSON_KEYS function
> --------------------------
>
> Key: CALCITE-2892
> URL: https://issues.apache.org/jira/browse/CALCITE-2892
> Project: Calcite
> Issue Type: Sub-task
> Reporter: Forward Xu
> Assignee: Forward Xu
> Priority: Major
> Labels: pull-request-available
> Fix For: 1.20.0
>
> Time Spent: 2h 50m
> Remaining Estimate: 0h
>
> [{{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]|
--
This message was sent by Atlassian JIRA
(v7.6.3#76005)
