pg with recursive

PG with recursive is a feature in PostgreSQL that allows you to perform recursive queries. It is commonly used to traverse hierarchical data structures such as trees or graphs.

The basic syntax for using PG with recursive is:

WITH RECURSIVE cte_name AS (
   SELECT initial_query
   UNION [ALL] 
   SELECT recursive_query FROM cte_name
)
SELECT * FROM cte_name;

The `initial_query` is the starting point of the recursion, and the `recursive_query` is the query that is repeatedly executed until the recursion is complete. The `UNION` operator is used to combine the initial and recursive queries, and the `ALL` keyword is optional and specifies to include duplicates in the result set.

The `SELECT` statement at the end of the query selects all the rows from the common table expression (`cte_name` in this example).

PG with recursive is a powerful tool for querying hierarchical data structures, but it can also be computationally expensive for large data sets. It is important to optimize your queries and use appropriate indexing to improve performance.