JSON data types and functionality [YSQL]
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JSON data types and functionality

Synopsis

JavaScript Object Notation (JSON) is a text format for the serialization of structured data. Its syntax and semantics are defined in RFC 7159. JSON is represented by Unicode characters, and such a representation is usually called a document. Whitespace outside of string values and object keys (see below) is insignificant.

YSQL supports two data types for representing a JSON document: json and jsonb. Both data types reject any JSON document that does not conform to RFC 7159. The json data type stores the text representation of a JSON document as presented. In contrast, the jsonb data type stores a parsed representation of the document hierarchy of subvalues in an appropriate internal format. Some people prefer the mnemonic "binary" for the "b" suffix; others prefer "better". Of course, it takes more computation to store a JSON document as a jsonb value than as json value. This cost is repaid when subvalues are operated on using the operators and functions described in this section.

JSON was invented as a data interchange format, initially to allow an arbitrary compound value in a JavaScript program to be serialized, transported as text, and then deserialized in another JavaScript program faithfully to reinstantiate the original compound value. Later, many other programming languages (including, now, SQL, and PL/pgSQL) support serialization to, and deserialization from, JSON. Moreover, it has become common to store JSON as the persistent representation of record in a table with just a primary key column and a json or jsonb column for facts that could be represented classically in a table design that conforms to the relational model. This pattern arose first in NoSQL databases, but it is now widespread in SQL databases.

Description

type_specification ::= { json | jsonb }

The following topics in this section discuss further details about JSON data types and functionality: