pg_class

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Overview

The pg_class stores information about tables and indexes in the database. It contains exactly one row per table (or index) created in the database. It mimics the pg_class PostgreSQL system catalog.

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Columns

The following columns are available for querying in pg_class:

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Example

1. Create a table and define its schema:

CREATE TABLE customer_orders (
    order_id INT,
    customer_id INT,
    order_date DATE,
    total_amount INT
);

2. Create an index on the customer_orders table for the customer_id column:

CREATE INDEX idx_customer_id ON customer_orders (customer_id);

3. Query the pg_class catalog to retrieve information about the customer_orders table and the index you’ve just created:

SELECT oid, relname, relkind, relhasindex, relnamespace 
FROM pg_class 
WHERE relname IN ('customer_orders', 'idx_customer_id');

4. The query will return information about the customer_orders table and the index:

 oid  |     relname     | relkind | relhasindex | relnamespace 
------+-----------------+---------+-------------+--------------
 1013 | idx_customer_id | i       | f           |            0
 1012 | customer_orders | r       | t           |            0
(2 rows)