Fix UNION planner datatype issue 66c0185a3 gave the planner the ability to have union child queries provide the union planner with pre-sorted input so that UNION queries could be more efficiently implemented using Merge Append.
That commit overlooked checking that the UNION target list and the union child target list's types all match. In some corner cases, this could result in the planner producing sorts using the sort operator of the top-level UNION's target list type rather than of the union child's target list's type. The implications of this range from silently working correctly, despite using the wrong sort operator all the way up to a segmentation fault. Here we fix by adjusting the planner so it makes no attempt to have the subquery produce pre-sorted results when the data type of the UNION target list and the types from the subquery target list don't match exactly. Backpatch to 17, where 66c0185a3 was introduced. Reported-by: Jason Smith <dqet...@126.com> Diagnosed-by: Tom Lane <t...@sss.pgh.pa.us> Bug: 18764 Discussion: https://postgr.es/m/18764-63ad667ea26e877a%40postgresql.org Backpatch-through: 17 Branch ------ REL_17_STABLE Details ------- https://git.postgresql.org/pg/commitdiff/5db9367e51136cb270feb79c741f68c1413dce78 Modified Files -------------- src/backend/optimizer/plan/planner.c | 24 ++++++++++++++++++++++-- 1 file changed, 22 insertions(+), 2 deletions(-)
