JSON Functions

You can use JSON functions to work with data in the JSON data type.

Functions that create JSON values

Function Name	Description
JSON_ARRAY()	Evaluates a (possibly empty) list of values and returns a JSON array containing those values
JSON_OBJECT()	Evaluates a (possibly empty) list of key-value pairs and returns a JSON object containing those pairs
JSON_QUOTE()	Returns a string as a JSON value with quotes

Functions that search JSON values

Function Name	Description
JSON_CONTAINS()	Indicates by returning 1 or 0 whether a given candidate JSON document is contained within a target JSON document
JSON_CONTAINS_PATH()	Returns 0 or 1 to indicate whether a JSON document contains data at a given path or paths
JSON_EXTRACT()	Returns data from a JSON document, selected from the parts of the document matched by the `path` arguments
->	Returns the value from a JSON column after the evaluating path; an alias for `JSON_EXTRACT(doc, path_literal)`
->>	Returns the value from a JSON column after the evaluating path and unquoting the result; an alias for `JSON_UNQUOTE(JSON_EXTRACT(doc, path_literal))`
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
JSON_SEARCH()	Search a JSON document for one or all matches of a string
MEMBER OF()	If the passed value is an element of the JSON array, returns 1. Otherwise, returns 0.
JSON_OVERLAPS()	Indicates whether two JSON documents have overlapping part. If yes, returns 1. If not, returns 0.

Functions that modify JSON values

Function Name	Description
JSON_APPEND()	An alias to `JSON_ARRAY_APPEND()`
JSON_ARRAY_APPEND()	Appends values to the end of the indicated arrays within a JSON document and returns the result
JSON_ARRAY_INSERT()	Insert values into the specified locations of a JSON document and returns the result
JSON_INSERT()	Inserts data into a JSON document and returns the result
JSON_MERGE_PATCH()	Merges two or more JSON documents, without preserving values of duplicate keys
JSON_MERGE_PRESERVE()	Merges two or more JSON documents by preserving all values
JSON_MERGE()	A deprecated alias for `JSON_MERGE_PRESERVE()`
JSON_REMOVE()	Removes data from a JSON document and returns the result
JSON_REPLACE()	Replaces existing values in a JSON document and returns the result
JSON_SET()	Inserts or updates data in a JSON document and returns the result
JSON_UNQUOTE()	Unquotes a JSON value and returns the result as a string

Functions that return JSON value attributes

Function Name	Description
JSON_DEPTH()	Returns the maximum depth of a JSON document
JSON_LENGTH()	Returns the length of a JSON document, or, if a path argument is given, the length of the value within the path
JSON_TYPE()	Returns a string indicating the type of a JSON value
JSON_VALID()	Checks if a json_doc is valid JSON.

Utility functions

Function Name	Description
JSON_PRETTY()	Pretty formatting of a JSON document
JSON_STORAGE_FREE()	Returns how much storage space was freed in the binary representation of the JSON value after it was updated in place.
JSON_STORAGE_SIZE()	Returns an approximate size of bytes required to store the json value. As the size does not account for TiKV using compression, the output of this function is not strictly compatible with MySQL.

Aggregate functions

Function Name	Description
JSON_ARRAYAGG()	Provides an aggregation of keys.
JSON_OBJECTAGG()	Provides an aggregation of values for a given key.

JSONPath

Many of JSON functions use JSONPath to select parts of a JSON document.

Symbol	Description
`$`	Document root
`.`	Member selection
`[]`	Array selection
`*`	Wildcard
`**`	Path wildcard
`[<n> to <n>]`	Array range selection

The subsequent content takes the following JSON document as an example to demonstrate how to use JSONPath:

{
    "database": {
        "name": "TiDB",
        "features": [
            "distributed",
            "scalable",
            "relational",
            "cloud native"
        ],
        "license": "Apache-2.0 license",
        "versions": [
            {
                "version": "v8.1.1",
                "type": "lts",
                "release_date": "2024-08-27" 
            },
            {
                "version": "v8.0.0",        
                "type": "dmr",
                "release_date": "2024-03-29"
            }
        ]
    },
    "migration_tool": {
        "name": "TiDB Data Migration",
        "features": [
            "MySQL compatible",            
            "Shard merging"
        ],
        "license": "Apache-2.0 license"
    }
}

JSONPath	Description	Example with `JSON_EXTRACT()`
`$`	The root of the document	Returns the full document
`$.database`	The `database` object	Returns the full structure starting with `"database"`. It does not include `"migration_tool"` and the structure below that.
`$.database.name`	The name of the database.	`"TiDB"`
`$.database.features`	All database features	`["distributed", "scalable", "relational", "cloud native"]`
`$.database.features[0]`	The first database feature.	`"distributed"`
`$.database.features[2]`	The third database feature.	`"relational"`
`$.database.versions[0].type`	The type of the first database version.	`"lts"`
`$.database.versions[*].release_date`	The release date for all versions.	`["2024-08-27","2024-03-29"]`
`$.*.features`	Two array's of features	`[["distributed", "scalable", "relational", "cloud native"], ["MySQL compatible", "Shard merging"]]`
`$**.version`	All versions, with path wildcard	`["v8.1.1","v8.0.0"]`
`$.database.features[0 to 2]`	Range of database features from the first to the third.	`["scalable","relational"]`

For more information, see the IETF draft for JSONPath.

Unsupported functions

JSON_SCHEMA_VALID()
JSON_SCHEMA_VALIDATION_REPORT()
JSON_TABLE()
JSON_VALUE()

For more information, see #14486.

MySQL compatibility

TiDB supports most of the JSON functions available in MySQL 8.0.