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https://issues.apache.org/jira/browse/CALCITE-2864?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16779941#comment-16779941
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Hongze Zhang edited comment on CALCITE-2864 at 2/28/19 12:27 AM:
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It seems that for now the {{JSON_DEPTH}} (also {{JSON_TYPE}}) expects a
{{JsonValueExpression}}[1] as input. It's a common pattern to construct a JSON
value. E.g. using {{JSON_DEPTH(col FORMAT AVRO)}} to handle avro JSON data (but
we now don't support avro format).
I think we can integrate {{JsonValueExpression}} into {{Expression}}[2] in
future(maybe in the fix of CALCITE-2869[3], although we did't start to discuss
that issue), then remove the parser changes of {{JSON_DEPTH}} and {{JSON_TYPE}}
and so on.
[1]
[https://github.com/apache/calcite/blob/5101703c3bb7e051766f9dc932534a0a7acba0c5/core/src/main/codegen/templates/Parser.jj#L4892]
[2]
[https://github.com/apache/calcite/blob/e3a319e1f79bc807327bd443433c50c4bbf20866/core/src/main/codegen/templates/Parser.jj#L2991]
[3] https://issues.apache.org/jira/browse/CALCITE-2869
was (Author: zhztheplayer):
It seems that for now the {{JSON_DEPTH}} (also {{JSON_TYPE}}) expects a
{{JsonValueExpression}}[1] as input. It's a common pattern to construct a JSON
value. E.g. using {{JSON_DEPTH(col FORMAT AVRO)}} to handle avro JSON data (but
we now don't support avro format).
I think we can integrate {{JsonValueExpression}} into {{Expression}}[2] in
future(maybe in the fix of 2869, although we did't start to discuss that
issue), then remove the parser changes of {{JSON_DEPTH}} and {{JSON_TYPE}} and
so on.
[1]
[https://github.com/apache/calcite/blob/5101703c3bb7e051766f9dc932534a0a7acba0c5/core/src/main/codegen/templates/Parser.jj#L4892]
[2]
[https://github.com/apache/calcite/blob/e3a319e1f79bc807327bd443433c50c4bbf20866/core/src/main/codegen/templates/Parser.jj#L2991]
> Add the JSON_DEPTH function
> ---------------------------
>
> Key: CALCITE-2864
> URL: https://issues.apache.org/jira/browse/CALCITE-2864
> Project: Calcite
> Issue Type: Sub-task
> Reporter: Forward Xu
> Assignee: Forward Xu
> Priority: Major
> Labels: pull-request-available
> Fix For: 1.19.0
>
> Time Spent: 50m
> Remaining Estimate: 0h
>
> Returns the maximum depth of a JSON document. Returns {{NULL}} if the
> argument is {{NULL}}. An error occurs if the argument is not a valid JSON
> document.
> An empty array, empty object, or scalar value has depth 1. A nonempty array
> containing only elements of depth 1 or nonempty object containing only member
> values of depth 1 has depth 2. Otherwise, a JSON document has depth greater
> than 2.
>
> Example Sql:
> SELECT JSON_DEPTH(v) AS c1
> ,JSON_DEPTH(JSON_VALUE(v, 'lax $.b' ERROR ON ERROR)) AS c2
> ,JSON_DEPTH(JSON_VALUE(v, 'strict $.a[0]' ERROR ON ERROR)) AS c3
> ,JSON_DEPTH(JSON_VALUE(v, 'strict $.a[1]' ERROR ON ERROR)) AS c4
> FROM (VALUES ('
> {"a": [10, true],"b": "[10, true]"}
> ')) AS t(v)
> limit 10;
> Result:
> c1 c2 c3 c4
> == == == ==
> 3 2 1 1
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