[jethkl]

a defense against collisions like this is through CTEs that select a minimal set of columns, with column names suitably selected and standardized:

  CTE_A AS (SELECT ... comment as comment_a from A...),
  CTE_B AS (SELECT ... comment as comment_b from B...)

[Cyberdog]

Isn't this a lot more work both for the user and the RDBMS than just using a relatively simple left join?