After a discussion with @andreimatei and @jordanlewis we can address the following :

• sql: bracket subquery results in wrong transaction status sql: bracket subquery results in wrong transaction status #22208 dup sql: mutations in statement sources don't work properly with limits #20732.
  • scheduled for 2.0
• sql: DMLs in statement sources don't work properly with limits sql: mutations in statement sources don't work properly with limits #20732 fixed sql: use a spool operator to fix the correctness of CTE mutations #23824
  • scheduled for 2.0
• sql: DMLs with RETURNING stream results that violate constraints sql: DMLs with RETURNING stream results that violate constraints #22304 fixed sql: fix the batching behavior of mutation statements, especially with RETURNING #23373
  • scheduled for 2.0.1
• sql: ON DELETE SET DEFAULT violates constraints sql: ON DELETE SET DEFAULT violates constraints #23361/ fixed sql: fix the batching behavior of mutation statements, especially with RETURNING #23373
  • scheduled for 2.0.1

Make this happen:

• row container for the results if the results are consumed in a surrounding query done sql: mutations in statement sources don't work properly with limits #20732
• ensure that no results to be streamed out before constraint validation occurs done sql: fix the batching behavior of mutation statements, especially with RETURNING #23373