Postgres JSONB query simplification

Question

I have some working code which pulls records from a forms table where 'mail@example.com' appears as a JSON value in one of the JSONB fields, column_a , column_b , column_c , or column_d .

SELECT * 
FROM forms f
WHERE exists (SELECT * 
              FROM jsonb_each_text(f.column_a) as e(ky,val)
              WHERE e.val = 'mail@example.com')   
UNION

SELECT * 
FROM forms f
WHERE exists (SELECT * 
              FROM jsonb_each_text(f.column_b) as e(ky,val)
              WHERE e.val = 'mail@example.com')
UNION

SELECT * 
FROM forms f
WHERE exists (SELECT * 
              FROM jsonb_each_text(f.column_c) as e(ky,val)
              WHERE e.val = 'mail@example.com')
UNION

SELECT * 
FROM forms f
WHERE exists (SELECT * 
              FROM jsonb_each_text(f.column_d) as e(ky,val)
              WHERE e.val = 'mail@example.com');

The JSON in the columns is similar to:

{ "xyz":"mail@example.com", "def":"mail2@example.com", "lmn":"mail3@example.com" }

Although the code works, it looks highly repetitive/long-winded. Given that I can't change the JSON structure, is there are more concise way of building this query, and what indexes should I be building for those columns for the best performance?

Answer 1

Why not use or ?

SELECT f.* 
FROM forms f
WHERE EXISTS (SELECT * 
              FROM jsonb_each_text(f.column_a) as e(ky,val)
              WHERE e.val = 'mail@example.com'
             ) OR
      EXISTS (SELECT * 
              FROM jsonb_each_text(f.column_b) as e(ky,val)
              WHERE e.val = 'mail@example.com'
             ) OR
      . . .

Presumably, this also eliminates the need for duplicate elimination, so the query should be faster as well.

EDIT:

If you want the sources, you can use correlated subqueries:

SELECT f.* 
FROM (SELECT f.*,
             EXISTS (SELECT * 
                     FROM jsonb_each_text(f.column_a) as e(ky,val)
                     WHERE e.val = 'mail@example.com'
                    ) as in_column_a,
             EXISTS (SELECT * 
                     FROM jsonb_each_text(f.column_b) as e(ky,val)
                     WHERE e.val = 'mail@example.com'
                    ) as in_column_b,
             . . .
      FROM forms f
     ) 
WHERE in_column_a OR in_column_b OR . . .

This is not quite as efficient, because it does not short-circuit the evaluation when it finds a match. On the other hand, it lists all columns that have a match.