From 6f3f3c1a2ef8872e16ec38a06c3b5c8f0b77e58f Mon Sep 17 00:00:00 2001
From: jian he <jian.universality@gmail.com>
Date: Sat, 24 Jan 2026 10:15:46 +0800
Subject: [PATCH v21 1/1] Add ON CONFLICT DO SELECT [FOR SHARE/UPDATE] misc fix

Discussion: https://postgr.es/m/5fca222d-62ae-4a2f-9fcb-0eca56277094@Spark
Discussion: https://postgr.es/m/2b5db2e6-8ece-44d0-9890-f256fdca9f7e@proxel.se
Discussion: https://postgr.es/m/d631b406-13b7-433e-8c0b-c6040c4b4663@Spark
---
 doc/src/sgml/dml.sgml                  |  4 ++--
 doc/src/sgml/ref/create_policy.sgml    |  8 ++++----
 src/backend/executor/nodeModifyTable.c | 11 +++++------
 3 files changed, 11 insertions(+), 12 deletions(-)

diff --git a/doc/src/sgml/dml.sgml b/doc/src/sgml/dml.sgml
index 988e19b347b..4d6938c7dde 100644
--- a/doc/src/sgml/dml.sgml
+++ b/doc/src/sgml/dml.sgml
@@ -388,8 +388,8 @@ UPDATE products SET price = price * 1.10
    <link linkend="sql-on-conflict"><literal>ON CONFLICT DO UPDATE</literal></link>
    clause, the old values will be non-<literal>NULL</literal> for conflicting
    rows.  Similarly, in an <command>INSERT</command> with an
-   <literal>ON CONFLICT DO SELECT</literal> clause, you can look at the old 
-   values to determine if your query inserted a row or not. 
+   <literal>ON CONFLICT DO SELECT</literal> clause, you can look at the old
+   values to determine if your query inserted a row or not.
    If a <command>DELETE</command> is turned into an
    <command>UPDATE</command> by a <link linkend="sql-createrule">rewrite rule</link>,
    the new values may be non-<literal>NULL</literal>.
diff --git a/doc/src/sgml/ref/create_policy.sgml b/doc/src/sgml/ref/create_policy.sgml
index 50425a5e769..932c4b82736 100644
--- a/doc/src/sgml/ref/create_policy.sgml
+++ b/doc/src/sgml/ref/create_policy.sgml
@@ -293,10 +293,10 @@ CREATE POLICY <replaceable class="parameter">name</replaceable> ON <replaceable
          silently ignored).
        </para>
        <para>
-         If an <literal>INSERT</literal> has an <literal>ON CONFLICT</literal> 
-         clause, <literal>SELECT</literal> permissions are required on the 
-         relation, and the rows proposed for insertion are checked using 
-         the relation's <literal>SELECT</literal> policies.  
+         If an <literal>INSERT</literal> has an <literal>ON CONFLICT</literal>
+         clause, <literal>SELECT</literal> permissions are required on the
+         relation, and the rows proposed for insertion are checked using
+         the relation's <literal>SELECT</literal> policies.
          If a row proposed for insertion does not satisfy the
          relation's <literal>SELECT</literal> policies, an error is thrown
          (the <literal>INSERT</literal> is <emphasis>never</emphasis> silently
diff --git a/src/backend/executor/nodeModifyTable.c b/src/backend/executor/nodeModifyTable.c
index 894dcb9467b..2f20ba71813 100644
--- a/src/backend/executor/nodeModifyTable.c
+++ b/src/backend/executor/nodeModifyTable.c
@@ -3017,12 +3017,11 @@ ExecOnConflictSelect(ModifyTableContext *context,
 
 	if (lockStrength == LCS_NONE)
 	{
-		/* Initialize "existing" - in the else branch, 
-		   this is done by ExecOnConflictLockRow */
-		bool found = table_tuple_fetch_row_version(relation, conflictTid, 
-			                                         SnapshotAny, existing);
-		/* Even if the tuple is deleted, it must still be physically present */
-		Assert(found);
+		if (!table_tuple_fetch_row_version(relation,
+										   conflictTid,
+										   SnapshotAny,
+										   existing))
+			elog(ERROR, "failed to fetch conflicting tuple for ON CONFLICT");
 	}
 	else
 	{
-- 
2.34.1