Add JSON datatype to PostgreSQL

by Joey Adams for PostgreSQL

JSON is a text serialization format similar in purpose to XML. PostgreSQL already has an XML datatype, along with XML access and manipulation functions such as xmlconcat, xmlforest, etc.. I propose adding a JSON datatype and related functions to PostgreSQL. Because JSON's structure is somewhat different than XML's, the json* functions will likely be different. When this project is completed, it will add a JSON datatype to PostgreSQL along with ways to convert sets to/from JSON.