PostgreSQL: No Hard Limit on IN Clause Parameters, But Beware of Performance Impact

• Alternatives for large lists:

  • Temporary tables: If you're dealing with a huge number of values, consider creating a temporary table to store those values and joining it with your main table. This can be more efficient.
  • Subqueries: You can also use a subquery to achieve the same result as a long IN clause.

-- This query finds prime numbers where n is in a long list of values
SELECT *
FROM primes
WHERE n IN (1, 2, 3, 5, 7, ..., 99991);

Alternative using temporary table (Better for large datasets):

-- Create a temporary table to store the values
CREATE TEMP TABLE IF NOT EXISTS large_numbers (value INTEGER);

-- Insert a large number of values into the temporary table
INSERT INTO large_numbers VALUES (1), (2), (3), ..., (99991);

-- Use JOIN with the temporary table
SELECT *
FROM primes p
JOIN large_numbers ln ON p.n = ln.value;

Alternative using subquery (Another option for large datasets):

-- Subquery to get the list of values
SELECT *
FROM primes p
WHERE n IN (
  SELECT value
  FROM (VALUES (1), (2), (3), ..., (99991)) AS subquery(value)
);

1. UNNEST operator: This operator allows you to "unwind" an array into rows. It's useful if you have your large number of values stored in an array variable within your program.

-- Example: Array containing values to check
DECLARE values INTEGER[];

SET values := ARRAY[1, 2, 3, 5, 7, ..., 99991];

-- Query using UNNEST
SELECT *
FROM primes p
WHERE p.n IN (UNNEST(values));