High Performance PostgreSQL for Rails

Using GIN Indexes with JSON

Generalized Inverted Index types or GIN indexes^[201] are a bit different from B-Tree indexes. Usually, B-Tree index entries point to single items. Exceptions to this are when columns hold nonunique values like names and duplicates are allowed. In those cases, a single B-Tree entry points to multiple rows.

However, even in that scenario, the row is present multiple times but is a single value (the name). What about data where the columns always contain multiple values or even data structures?

For example, jsonb columns with JSON formatted text could contain lots of “keys” within a structure of data. Despite that structure of data that’s not one single value, you still may have the need to efficiently query for data ...