# JSON Object Key: `container.object.json` JavaScript Object Notation (JSON) object stored as VARCHAR. Represents structured key-value data that may be nested. Page: Samples: `{"user": "john", "age": 30}`, `{"name": "Alice", "email": "alice@example.com", "active": true}`, `{"nested": {"key": "value"}}` ## Background ### Origin Douglas Crockford originally specified the JSON format in the early 2000s.[[1]](https://en.wikipedia.org/wiki/JSON) JSON grew out of a need for a real-time server-to-browser session communication protocol without using browser plugins such as Flash or Java applets.[[1]](https://en.wikipedia.org/wiki/JSON) The acronym JSON originated at State Software, a company cofounded by Crockford and others in March 2001.[[1]](https://en.wikipedia.org/wiki/JSON) JSON is based on a subset of the JavaScript Programming Language Standard ECMA-262 3rd Edition - December 1999.[[2]](https://www.json.org/json-en.html) JSON.org describes JSON as built on two structures: a collection of name/value pairs and an ordered list of values.[[2]](https://www.json.org/json-en.html) JSON.org notes that in various languages the collection of name/value pairs is realised as an object, record, struct, dictionary, hash table, keyed list or associative array.[[2]](https://www.json.org/json-en.html) JSON.org defines an object as an unordered set of name/value pairs that begins with a left brace and ends with a right brace.[[2]](https://www.json.org/json-en.html) Ecma International published the first edition of ECMA-404 in October 2013.[[3]](https://ecma-international.org/publications-and-standards/standards/ecma-404/) The second edition of ECMA-404, The JSON data interchange syntax, is dated December 2017.[[3]](https://ecma-international.org/publications-and-standards/standards/ecma-404/) ECMA-404 carries the ISO/IEC number 21778.[[3]](https://ecma-international.org/publications-and-standards/standards/ecma-404/) RFC 8259, edited by T. Bray and published by the IETF in December 2017, obsoletes RFC 7159.[[4]](https://www.rfc-editor.org/rfc/rfc8259.txt) RFC 8259 is the current version of the Internet Standard STD 90.[[1]](https://en.wikipedia.org/wiki/JSON) ECMA-404 states that its goal is only to define the syntax of valid JSON texts, not to provide any semantics or interpretation of them.[[3]](https://ecma-international.org/publications-and-standards/standards/ecma-404/) ### Use Under RFC 8259, an object is a pair of curly brackets surrounding zero or more name/value pairs, in which each name is a string followed by a single colon.[[4]](https://www.rfc-editor.org/rfc/rfc8259.txt) RFC 8259 says the names within an object SHOULD be unique.[[4]](https://www.rfc-editor.org/rfc/rfc8259.txt) RFC 8259 warns that when names within an object are not unique, the behaviour of software receiving the object is unpredictable.[[4]](https://www.rfc-editor.org/rfc/rfc8259.txt) RFC 8259 observes that many implementations report only the last name/value pair for a repeated name, while others report an error or report every pair.[[4]](https://www.rfc-editor.org/rfc/rfc8259.txt) Python's json module by default ignores all but the last name-value pair for a repeated name.[[5]](https://docs.python.org/3/library/json.html) RFC 8259 notes that JSON parsing libraries differ as to whether they make the ordering of object members visible to calling software.[[4]](https://www.rfc-editor.org/rfc/rfc8259.txt) Treat key order as meaningless and duplicate keys as a data-quality problem to report, rather than trusting whichever value your parser happens to keep. (Meridian's view) RFC 8259 requires JSON text exchanged between systems outside a closed ecosystem to be encoded in UTF-8.[[4]](https://www.rfc-editor.org/rfc/rfc8259.txt) In DuckDB, the JSON logical type is physically stored as a VARCHAR, with the restriction that the text must be valid JSON.[[6]](https://duckdb.org/docs/current/data/json/json_type) DuckDB's documentation shows that whitespace and key order are significant when two JSON values are compared.[[6]](https://duckdb.org/docs/current/data/json/json_type) DuckDB allows duplicate keys in JSON objects.[[6]](https://duckdb.org/docs/current/data/json/json_type) DuckDB can cast a JSON value to its STRUCT type, as in '{"duck": 42}'::JSON::STRUCT(duck INTEGER).[[6]](https://duckdb.org/docs/current/data/json/json_type) PostgreSQL offers two types for JSON data, json and jsonb.[[7]](https://www.postgresql.org/docs/current/datatype-json.html) PostgreSQL's json type stores an exact copy of the input text, preserving key order and keeping duplicate keys.[[7]](https://www.postgresql.org/docs/current/datatype-json.html) PostgreSQL's jsonb type does not preserve the order of object keys and keeps only the last value of a duplicated key.[[7]](https://www.postgresql.org/docs/current/datatype-json.html) PostgreSQL's documentation says most applications should prefer to store JSON data as jsonb.[[7]](https://www.postgresql.org/docs/current/datatype-json.html) ## Sources 1. [JSON - Wikipedia](https://en.wikipedia.org/wiki/JSON) — secondary source 2. [JSON](https://www.json.org/json-en.html) — secondary source 3. [ECMA-404 - Ecma International](https://ecma-international.org/publications-and-standards/standards/ecma-404/) — catalogue entry 4. [The JavaScript Object Notation (JSON) Data Interchange Format](https://www.rfc-editor.org/rfc/rfc8259.txt) — standard 5. [json — JSON encoder and decoder — Python 3.15.0 documentation](https://docs.python.org/3/library/json.html) — documentation 6. [JSON Type – DuckDB](https://duckdb.org/docs/current/data/json/json_type) — documentation 7. [PostgreSQL: Documentation: 18: 8.14. JSON Types](https://www.postgresql.org/docs/current/datatype-json.html) — documentation