From 606df58881bfcdf50eea93d34308591bd3997fb5 Mon Sep 17 00:00:00 2001 From: Noah Misch Date: Mon, 3 Nov 2025 20:19:10 +0100 Subject: [PATCH v11 1/6] Doc: cover index CONCURRENTLY causing errors in INSERT ... ON CONFLICT. Author: Mikhail Nikalayeu Reviewed-by: Noah Misch Discussion: https://postgr.es/m/CANtu0ojXmqjmEzp-=aJSxjsdE76iAsRgHBoK0QtYHimb_mEfsg@mail.gmail.com Backpatch-through: 13 --- doc/src/sgml/ref/insert.sgml | 9 +++++++++ src/backend/optimizer/util/plancat.c | 5 +++++ 2 files changed, 14 insertions(+) diff --git a/doc/src/sgml/ref/insert.sgml b/doc/src/sgml/ref/insert.sgml index 3f139917790..b337f2ee555 100644 --- a/doc/src/sgml/ref/insert.sgml +++ b/doc/src/sgml/ref/insert.sgml @@ -594,6 +594,15 @@ INSERT INTO table_name [ AS + + + While CREATE INDEX CONCURRENTLY or REINDEX + CONCURRENTLY is running on a unique index, INSERT + ... ON CONFLICT statements on the same table may unexpectedly + fail with a unique violation. + + + diff --git a/src/backend/optimizer/util/plancat.c b/src/backend/optimizer/util/plancat.c index da5d901ec3c..4b62a9756c1 100644 --- a/src/backend/optimizer/util/plancat.c +++ b/src/backend/optimizer/util/plancat.c @@ -789,6 +789,11 @@ find_relation_notnullatts(PlannerInfo *root, Oid relid) * the purposes of inference. If no opclass (or collation) is specified, then * all matching indexes (that may or may not match the default in terms of * each attribute opclass/collation) are used for inference. + * + * Note: during index CONCURRENTLY operations, different transactions + * may reference different sets of arbiter indexes. This can lead to false + * unique constraint violations that wouldn't occur during normal operations. + * For more information, see insert.sgml. */ List * infer_arbiter_indexes(PlannerInfo *root) -- 2.43.0