How Can I Efficiently Query JSONB Arrays in Postgres for Millions of Rows?

Utilizing JSONB Operators and GIN Indexing for Postgres Queries

In Postgres, accessing JSON array elements requires a syntax different from the approach you have outlined. To access the first element of a JSON array, use a zero-indexed expression instead of your previous attempt.

The recommended query syntax for this scenario is:

e->0->>'event_slug'

Moreover, Postgres offers comprehensive support for jsonb data types. With Postgres 12 and later, you can utilize SQL/JSON path functionality for "greater than" or "less than" comparisons using jsonb columns.

For your specific query, the recommended approach is to create a GIN index using the jsonb_path_ops operator class:

CREATE INDEX locations_events_gin_idx ON locations USING GIN (events jsonb_path_ops);

With this index in place, the following query should utilize the index and provide efficient results:

SELECT l.*
FROM locations l
WHERE l.events @? '$[*] ? (@.event_slug == "test_1") ? (@.end_time.datetime() < "2014-10-13".datetime())'

In older versions of Postgres without direct "greater than" or "less than" operators for jsonb, a materialized view can be employed to achieve similar performance. This involves storing relevant attributes in normalized form, allowing you to create traditional btree indexes for efficient querying.

Considering your use case with millions of rows containing approximately 10 events each, both the GIN index and materialized view approaches are viable solutions. The best option depends on factors such as the complexity of your queries, the frequency of updates, and the desired performance characteristics.

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