v12-0002-Modify-the-infer_arbiter_indexes-function-to-con.patch

From 7ae8d431ec01c1c89a8de675dd05d036e37f714c Mon Sep 17 00:00:00 2001
From: nkey <mihailnikalayeu@gmail.com>
Date: Thu, 20 Feb 2025 14:50:58 +0300
Subject: [PATCH v12 2/5] Modify the infer_arbiter_indexes function to consider
 both indisvalid and indisready indexes. Ensure that at least one indisvalid
 index is still required.

The change ensures that all concurrent transactions utilize the same set of indexes as arbiters. This uniformity is required to avoid conditions that could lead to "duplicate key value violates unique constraint" errors during UPSERT operations.

The patch resolves the issues in the following specs:
* reindex_concurrently_upsert
* index_concurrently_upsert
* index_concurrently_upsert_predicate

Despite the patch, the following specs are still affected:
* reindex_concurrently_upsert_partitioned
* reindex_concurrently_upsert_on_constraint
---
 src/backend/optimizer/util/plancat.c | 18 +++++++++++++-----
 1 file changed, 13 insertions(+), 5 deletions(-)

diff --git a/src/backend/optimizer/util/plancat.c b/src/backend/optimizer/util/plancat.c
index d950bd93002..a8ae4401006 100644
--- a/src/backend/optimizer/util/plancat.c
+++ b/src/backend/optimizer/util/plancat.c
@@ -814,6 +814,7 @@ infer_arbiter_indexes(PlannerInfo *root)
 
 	/* Results */
 	List	   *results = NIL;
+	bool	   foundValid = false;
 
 	/*
 	 * Quickly return NIL for ON CONFLICT DO NOTHING without an inference
@@ -907,7 +908,13 @@ infer_arbiter_indexes(PlannerInfo *root)
 		idxRel = index_open(indexoid, rte->rellockmode);
 		idxForm = idxRel->rd_index;
 
-		if (!idxForm->indisvalid)
+		/*
+		 * We need to consider both indisvalid and indisready indexes because
+		 * them may become indisvalid before execution phase. It is required
+		 * to keep set of indexes used as arbiter to be the same for all
+		 * concurrent transactions.
+		 */
+		if (!idxForm->indisready)
 			goto next;
 
 		/*
@@ -929,10 +936,9 @@ infer_arbiter_indexes(PlannerInfo *root)
 						 errmsg("ON CONFLICT DO UPDATE not supported with exclusion constraints")));
 
 			results = lappend_oid(results, idxForm->indexrelid);
-			list_free(indexList);
+			foundValid |= idxForm->indisvalid;
 			index_close(idxRel, NoLock);
-			table_close(relation, NoLock);
-			return results;
+			break;
 		}
 		else if (indexOidFromConstraint != InvalidOid)
 		{
@@ -1033,6 +1039,7 @@ infer_arbiter_indexes(PlannerInfo *root)
 			goto next;
 
 		results = lappend_oid(results, idxForm->indexrelid);
+		foundValid |= idxForm->indisvalid;
 next:
 		index_close(idxRel, NoLock);
 	}
@@ -1040,7 +1047,8 @@ next:
 	list_free(indexList);
 	table_close(relation, NoLock);
 
-	if (results == NIL)
+	/* It is required to have at least one indisvalid index during the planning. */
+	if (results == NIL || !foundValid)
 		ereport(ERROR,
 				(errcode(ERRCODE_INVALID_COLUMN_REFERENCE),
 				 errmsg("there is no unique or exclusion constraint matching the ON CONFLICT specification")));
-- 
2.43.0