Would there be any performance difference between these two queries?

SELECT
  table1.column1,
  table2.column1
FROM table1
JOIN table2 ON table2.id = table1.id
WHERE table1.a = 'foo'
  AND table1.b = 'bar'
  AND table2.a = 'foo'
  AND table2.b = 'bar'

SELECT
  table1_filtered.column1,
  table2_filtered.column1
FROM (
  SELECT column1
  FROM table1
  WHERE a = 'foo'
    AND b = 'bar'
) table1_filtered
JOIN (
  SELECT column1
  FROM table2
  WHERE a = 'foo'
    AND b = 'bar'
) table2_filtered ON table2_filtered.id = table1_filtered.id

With these kind of things, you need to benchmark it with your data. You can also try an

INNER JOIN

, it allows the query optimiser to do some optimisations in some cases.

Okay thanks. My thinking was maybe filtering the tables before joining them might make the joining quicker. Thanks for the tip!