How to merge two JSON columns in PostgreSQL?
Using Postgres 9.4, I am looking for a way to merge two (or more) json or jsonb columns in a query. Consider the following table as an example:
What are the rules for a JSON merge?
This kind of “deep merge” can be interpreted quite differently, depending on your use case. For completeness, my intuition usually dictates the following rules: object + object: Every property survives from each object, which is not in the other object (JSON’s null value is considered to be in the object, if it’s explicitly mentioned).
Which is the only aggregate function in PostgreSQL?
Let’s take a look at some aggregate functions and hope for the best… http://www.postgresql.org/docs/9.4/static/functions-aggregate.html json_object_agg Is the only aggregate function that build objects, that’s our only chance to tackle this problem. The trick here is to find the correct way to feed the json_object_agg function.
What kind of JSON is used in PostgreSQL?
5 PostgreSql actually has two different data types that can be used to represent JSON: json and jsonb. These are “almost identical”, however, one should use jsonb by default, and only use json for legacy reasons. Practically, jsonb is much more efficient as it is stored on disk in binary format, whereas json is stored in plain text format.
Can a JSON merge be moved to a database?
The logic for merging JSON can feasibly be moved to the database, and that is the next approach that we will take a look at. After all, when working with documents, we can still adhere to the same principles that we would for relational data.
Can you use PostgreSQL as a document database?
The support for relational and document database paradigms is a potent combination, as it is feasible to use PostgreSql as a document database – one of the main categories of NoSql databases. A pattern for doing this is to create tables with just two columns: an id column that is the (indexed) primary key for the document, and