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Update descriptions of JSON functions #17654

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Update descriptions of JSON functions #17654

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Update docs for JSON_MERGE
writer-jill Jan 22, 2025
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Update docs/querying/sql-json-functions.md
techdocsmith Jan 29, 2025
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14 changes: 7 additions & 7 deletions docs/querying/sql-json-functions.md
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Expand Up @@ -32,19 +32,19 @@ sidebar_label: "JSON functions"

Druid supports nested columns, which provide optimized storage and indexes for nested data structures. See [Nested columns](./nested-columns.md) for more information.

You can use the following JSON functions to extract, transform, and create `COMPLEX<json>` values.
You can use the following JSON functions to extract, transform, and create `COMPLEX<json>` objects.

| Function | Notes |
| --- | --- |
|`JSON_KEYS(expr, path)`| Returns an array of field names from `expr` at the specified `path`.|
|`JSON_OBJECT(KEY expr1 VALUE expr2[, KEY expr3 VALUE expr4, ...])` | Constructs a new `COMPLEX<json>` object. The `KEY` expressions must evaluate to string types. The `VALUE` expressions can be composed of any input type, including other `COMPLEX<json>` values. `JSON_OBJECT` can accept colon-separated key-value pairs. The following syntax is equivalent: `JSON_OBJECT(expr1:expr2[, expr3:expr4, ...])`.|
|`JSON_MERGE(expr1, expr2[, expr3 ...])`| Merges two or more JSON `STRING` or `COMPLEX<json>` into one. Preserves the rightmost value when there are key overlaps. Returning always a `COMPLEX<json>` type.|
|`JSON_MERGE(expr1, expr2[, expr3 ...])`| Merges two or more JSON `STRING` or `COMPLEX<json>` into one, preserving the rightmost value when there are key overlaps. Always returns a `COMPLEX<json>` object.|
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|`JSON_OBJECT(KEY expr1 VALUE expr2[, KEY expr3 VALUE expr4, ...])` | Constructs a new `COMPLEX<json>` object from one or more expressions. The `KEY` expressions must evaluate to string types. The `VALUE` expressions can be composed of any input type, including other `COMPLEX<json>` objects. The function can accept colon-separated key-value pairs. The following syntax is equivalent: `JSON_OBJECT(expr1:expr2[, expr3:expr4, ...])`.|
|`JSON_PATHS(expr)`| Returns an array of all paths which refer to literal values in `expr` in JSONPath format. |
|`JSON_QUERY(expr, path)`| Extracts a `COMPLEX<json>` value from `expr`, at the specified `path`. |
|`JSON_QUERY_ARRAY(expr, path)`| Extracts an `ARRAY<COMPLEX<json>>` value from `expr` at the specified `path`. If value is not an `ARRAY`, it gets translated into a single element `ARRAY` containing the value at `path`. The primary use of this function is to extract arrays of objects to use as inputs to other [array functions](./sql-array-functions.md).|
|`JSON_VALUE(expr, path [RETURNING sqlType])`| Extracts a literal value from `expr` at the specified `path`. If you specify `RETURNING` and an SQL type name (such as `VARCHAR`, `BIGINT`, `DOUBLE`, etc) the function plans the query using the suggested type. Otherwise, it attempts to infer the type based on the context. If it can't infer the type, it defaults to `VARCHAR`.|
|`PARSE_JSON(expr)`|Parses `expr` into a `COMPLEX<json>` object. This operator deserializes JSON values when processing them, translating stringified JSON into a nested structure. If the input is not a `VARCHAR` or it is invalid JSON, this function will result in an error.|
|`TRY_PARSE_JSON(expr)`|Parses `expr` into a `COMPLEX<json>` object. This operator deserializes JSON values when processing them, translating stringified JSON into a nested structure. If the input is not a `VARCHAR` or it is invalid JSON, this function will result in a `NULL` value.|
|`JSON_QUERY_ARRAY(expr, path)`| Extracts an `ARRAY<COMPLEX<json>>` value from `expr` at the specified `path`. If the value isn't an `ARRAY`, the function translates it into a single element `ARRAY` containing the value at `path`. Mainly used to extract arrays of objects to use as inputs to other [array functions](./sql-array-functions.md).|
|`JSON_VALUE(expr, path [RETURNING sqlType])`| Extracts a literal value from `expr` at the specified `path`. If you include `RETURNING` and specify a SQL type (such as `VARCHAR`, `BIGINT`, `DOUBLE`) the function plans the query using the suggested type. If `RETURNING` isn't included, the function attempts to infer the type based on the context. If the function can't infer the type, it defaults to `VARCHAR`.|
|`PARSE_JSON(expr)`|Parses `expr` into a `COMPLEX<json>` object. This function deserializes JSON values when processing them, translating stringified JSON into a nested structure. If the input is invalid JSON or not a `VARCHAR`, it returns an error.|
|`TRY_PARSE_JSON(expr)`|Parses `expr` into a `COMPLEX<json>` object. This operator deserializes JSON values when processing them, translating stringified JSON into a nested structure. If the input is invalid JSON or not a `VARCHAR`, it returns a `NULL` value.|
|`TO_JSON_STRING(expr)`|Serializes `expr` into a JSON string.|

### JSONPath syntax
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