v54-0002-Report-error-for-ddls-on-conflict-log-tables.patch

From a346e85220725cdfca5372852cb2d0746f7fcfad Mon Sep 17 00:00:00 2001
From: Dilip Kumar <dilipkumarb@google.com>
Date: Wed, 10 Jun 2026 16:52:46 +0530
Subject: [PATCH v54 2/6] Report error for ddls on conflict log tables

---
 src/backend/catalog/aclchk.c        |  8 ++++
 src/backend/commands/lockcmds.c     | 21 ++++++++-
 src/backend/commands/policy.c       | 12 +++++
 src/backend/commands/statscmds.c    | 14 ++++++
 src/backend/commands/tablecmds.c    | 73 +++++++++++++++++++++++++++++
 src/backend/commands/trigger.c      | 25 ++++++++++
 src/backend/rewrite/rewriteDefine.c | 22 +++++++++
 7 files changed, 174 insertions(+), 1 deletion(-)

diff --git a/src/backend/catalog/aclchk.c b/src/backend/catalog/aclchk.c
index 64e176652d1..ae58de452d6 100644
--- a/src/backend/catalog/aclchk.c
+++ b/src/backend/catalog/aclchk.c
@@ -3674,6 +3674,14 @@ pg_namespace_aclmask_ext(Oid nsp_oid, Oid roleid,
 	Acl		   *acl;
 	Oid			ownerId;
 
+	/*
+	 * Disallow creation in the conflict schema for everyone, including
+	 * superusers, unless in binary-upgrade mode.
+	 */
+	if (!IsBinaryUpgrade && (mask & ACL_CREATE) &&
+		IsConflictLogTableNamespace(nsp_oid))
+		return mask & ~ACL_CREATE;
+
 	/* Superusers bypass all permission checking. */
 	if (superuser_arg(roleid))
 		return mask;
diff --git a/src/backend/commands/lockcmds.c b/src/backend/commands/lockcmds.c
index f66b8f17b9b..128c11cc36f 100644
--- a/src/backend/commands/lockcmds.c
+++ b/src/backend/commands/lockcmds.c
@@ -16,6 +16,7 @@
 
 #include "access/table.h"
 #include "access/xact.h"
+#include "catalog/catalog.h"
 #include "catalog/namespace.h"
 #include "catalog/pg_inherits.h"
 #include "commands/lockcmds.h"
@@ -83,7 +84,18 @@ RangeVarCallbackForLockTable(const RangeVar *rv, Oid relid, Oid oldrelid,
 		return;					/* woops, concurrently dropped; no permissions
 								 * check */
 
-	/* Currently, we only allow plain tables or views to be locked */
+	/*
+	 * Note: Conflict log tables are deliberately NOT blocked here, even though
+	 * other direct DDL on them is rejected elsewhere. pg_dump relies on being
+	 * able to take an ACCESS SHARE lock on these tables to safely dump their
+	 * definitions during a binary upgrade, so we permit LOCK commands on them
+	 * and treat them like ordinary tables here. It's true that a strong lock
+	 * (ShareLock or above) on such a table would conflict with the
+	 * RowExclusiveLock taken by the apply worker's inserts and could stall
+	 * conflict logging as well as the apply worker for as long as it is held.
+	 * But locking a system-managed conflict log table is an unusual thing to
+	 * do, and it doesn't seem worth the trouble of filtering by lock mode here.
+	 */
 	if (relkind != RELKIND_RELATION && relkind != RELKIND_PARTITIONED_TABLE &&
 		relkind != RELKIND_VIEW)
 		ereport(ERROR,
@@ -198,6 +210,13 @@ LockViewRecurse_walker(Node *node, LockViewRecurse_context *context)
 				relkind != RELKIND_VIEW)
 				continue;
 
+			/*
+			 * Conflict log tables are managed by the system for logical
+			 * and should not be locked explicitly.
+			 */
+			if (IsConflictLogTableNamespace(get_rel_namespace(relid)))
+				continue;
+
 			/*
 			 * We might be dealing with a self-referential view.  If so, we
 			 * can just stop recursing, since we already locked it.
diff --git a/src/backend/commands/policy.c b/src/backend/commands/policy.c
index 21b8eebe32d..10ea599bac0 100644
--- a/src/backend/commands/policy.c
+++ b/src/backend/commands/policy.c
@@ -79,6 +79,18 @@ RangeVarCallbackForPolicy(const RangeVar *rv, Oid relid, Oid oldrelid,
 	if (!object_ownercheck(RelationRelationId, relid, GetUserId()))
 		aclcheck_error(ACLCHECK_NOT_OWNER, get_relkind_objtype(get_rel_relkind(relid)), rv->relname);
 
+	/*
+	 * Conflict log tables are used internally for logical replication conflict
+	 * logging and should not be modified directly, as it could disrupt
+	 * conflict logging.
+	 */
+	if (IsConflictLogTableClass(classform))
+		ereport(ERROR,
+				(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
+				 errmsg("permission denied: \"%s\" is a conflict log table",
+						rv->relname),
+				 errdetail("Conflict log tables are system-managed tables for logical replication conflicts.")));
+
 	/* No system table modifications unless explicitly allowed. */
 	if (!allowSystemTableMods && IsSystemClass(relid, classform))
 		ereport(ERROR,
diff --git a/src/backend/commands/statscmds.c b/src/backend/commands/statscmds.c
index b354723be44..e8fa81ef555 100644
--- a/src/backend/commands/statscmds.c
+++ b/src/backend/commands/statscmds.c
@@ -147,6 +147,20 @@ CreateStatistics(CreateStatsStmt *stmt, bool check_rights)
 			aclcheck_error(ACLCHECK_NOT_OWNER, get_relkind_objtype(rel->rd_rel->relkind),
 						   RelationGetRelationName(rel));
 
+		/*
+		 * Conflict log tables are system-managed tables used internally for
+		 * logical replication conflict logging. Unlike user tables, they are
+		 * not expected to have complex query usage, so to keep things simple,
+		 * user-defined extended statistics are not required or supported at
+		 * present.
+		 */
+		if (IsConflictLogTableClass(rel->rd_rel))
+			ereport(ERROR,
+					(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
+					 errmsg("permission denied: \"%s\" is a conflict log table",
+							RelationGetRelationName(rel)),
+					 errdetail("Conflict log tables are system-managed tables for logical replication conflicts.")));
+
 		/* Creating statistics on system catalogs is not allowed */
 		if (!allowSystemTableMods && IsSystemRelation(rel))
 			ereport(ERROR,
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 9af3b616bfa..ac0a5736700 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -2750,6 +2750,18 @@ MergeAttributes(List *columns, const List *supers, char relpersistence,
 					 errmsg("cannot inherit from partition \"%s\"",
 							RelationGetRelationName(relation))));
 
+		/*
+		 * Conflict log tables are managed by the system for logical
+		 * replication and should not be used as parent tables, as
+		 * inheritance could interfere with the logging behavior.
+		 */
+		if (IsConflictLogTableNamespace(relation->rd_rel->relnamespace))
+			ereport(ERROR,
+					(errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					 errmsg("cannot inherit from conflict log table \"%s\"",
+							RelationGetRelationName(relation)),
+					 errdetail("Conflict log tables are system-managed tables for logical replication conflicts.")));
+
 		if (relation->rd_rel->relkind != RELKIND_RELATION &&
 			relation->rd_rel->relkind != RELKIND_FOREIGN_TABLE &&
 			relation->rd_rel->relkind != RELKIND_PARTITIONED_TABLE)
@@ -3887,6 +3899,19 @@ renameatt_check(Oid myrelid, Form_pg_class classform, bool recursing)
 	if (!object_ownercheck(RelationRelationId, myrelid, GetUserId()))
 		aclcheck_error(ACLCHECK_NOT_OWNER, get_relkind_objtype(get_rel_relkind(myrelid)),
 					   NameStr(classform->relname));
+
+	/*
+	 * Conflict log tables are used internally for logical replication conflict
+	 * logging and should not be modified directly, as it could disrupt
+	 * conflict logging.
+	 */
+	if (IsConflictLogTableClass(classform))
+		ereport(ERROR,
+				(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
+				 errmsg("permission denied: \"%s\" is a conflict log table",
+						NameStr(classform->relname)),
+				 errdetail("Conflict log tables are system-managed tables for logical replication conflicts.")));
+
 	if (!allowSystemTableMods && IsSystemClass(myrelid, classform))
 		ereport(ERROR,
 				(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
@@ -6889,6 +6914,18 @@ ATSimplePermissions(AlterTableType cmdtype, Relation rel, int allowed_targets)
 		aclcheck_error(ACLCHECK_NOT_OWNER, get_relkind_objtype(rel->rd_rel->relkind),
 					   RelationGetRelationName(rel));
 
+	/*
+	 * Conflict log tables are used internally for logical replication conflict
+	 * logging and should not be altered directly, as it could disrupt conflict
+	 * logging.
+	 */
+	if (IsConflictLogTableClass(rel->rd_rel))
+		ereport(ERROR,
+				(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
+				 errmsg("permission denied: \"%s\" is a conflict log table",
+						RelationGetRelationName(rel)),
+				 errdetail("Conflict log tables are system-managed tables for logical replication conflicts.")));
+
 	if (!allowSystemTableMods && IsSystemRelation(rel))
 		ereport(ERROR,
 				(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
@@ -10198,6 +10235,18 @@ ATAddForeignKeyConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel,
 				 errmsg("referenced relation \"%s\" is not a table",
 						RelationGetRelationName(pkrel))));
 
+	/*
+	 * Conflict log tables are used internally for logical replication conflict
+	 * logging and should not be referenced by foreign keys, as it could
+	 * disrupt conflict logging.
+	 */
+	if (IsConflictLogTableClass(pkrel->rd_rel))
+		ereport(ERROR,
+				(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
+				 errmsg("permission denied: \"%s\" is a conflict log table",
+						RelationGetRelationName(pkrel)),
+				 errdetail("Conflict log tables are system-managed tables for logical replication conflicts.")));
+
 	if (!allowSystemTableMods && IsSystemRelation(pkrel))
 		ereport(ERROR,
 				(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
@@ -19818,6 +19867,18 @@ RangeVarCallbackOwnsRelation(const RangeVar *relation,
 		aclcheck_error(ACLCHECK_NOT_OWNER, get_relkind_objtype(get_rel_relkind(relId)),
 					   relation->relname);
 
+	/*
+	 * Conflict log tables are used internally for logical replication conflict
+	 * logging and should not be modified directly, as it could disrupt
+	 * conflict logging.
+	 */
+	if (IsConflictLogTableClass((Form_pg_class) GETSTRUCT(tuple)))
+		ereport(ERROR,
+				(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
+				 errmsg("permission denied: \"%s\" is a conflict log table",
+						relation->relname),
+				 errdetail("Conflict log tables are system-managed tables for logical replication conflicts.")));
+
 	if (!allowSystemTableMods &&
 		IsSystemClass(relId, (Form_pg_class) GETSTRUCT(tuple)))
 		ereport(ERROR,
@@ -19853,6 +19914,18 @@ RangeVarCallbackForAlterRelation(const RangeVar *rv, Oid relid, Oid oldrelid,
 	if (!object_ownercheck(RelationRelationId, relid, GetUserId()))
 		aclcheck_error(ACLCHECK_NOT_OWNER, get_relkind_objtype(get_rel_relkind(relid)), rv->relname);
 
+	/*
+	 * Conflict log tables are used internally for logical replication conflict
+	 * logging and should not be altered directly, as it could disrupt conflict
+	 * logging.
+	 */
+	if (IsConflictLogTableClass(classform))
+		ereport(ERROR,
+				(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
+				 errmsg("permission denied: \"%s\" is a conflict log table",
+						rv->relname),
+				 errdetail("Conflict log tables are system-managed tables for logical replication conflicts.")));
+
 	/* No system table modifications unless explicitly allowed. */
 	if (!allowSystemTableMods && IsSystemClass(relid, classform))
 		ereport(ERROR,
diff --git a/src/backend/commands/trigger.c b/src/backend/commands/trigger.c
index b87b4b40d07..de7957a15f7 100644
--- a/src/backend/commands/trigger.c
+++ b/src/backend/commands/trigger.c
@@ -314,6 +314,18 @@ CreateTriggerFiringOn(const CreateTrigStmt *stmt, const char *queryString,
 						RelationGetRelationName(rel)),
 				 errdetail_relkind_not_supported(rel->rd_rel->relkind)));
 
+	/*
+	 * Conflict log tables are used internally for logical replication conflict
+	 * logging and should not have triggers, as it could disrupt conflict
+	 * logging.
+	 */
+	if (IsConflictLogTableClass(rel->rd_rel))
+		ereport(ERROR,
+				(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
+				 errmsg("permission denied: \"%s\" is a conflict log table",
+						RelationGetRelationName(rel)),
+				 errdetail("Conflict log tables are system-managed tables for logical replication conflicts.")));
+
 	if (!allowSystemTableMods && IsSystemRelation(rel))
 		ereport(ERROR,
 				(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
@@ -1443,6 +1455,19 @@ RangeVarCallbackForRenameTrigger(const RangeVar *rv, Oid relid, Oid oldrelid,
 	/* you must own the table to rename one of its triggers */
 	if (!object_ownercheck(RelationRelationId, relid, GetUserId()))
 		aclcheck_error(ACLCHECK_NOT_OWNER, get_relkind_objtype(get_rel_relkind(relid)), rv->relname);
+
+	/*
+	 * Conflict log tables are used internally for logical replication conflict
+	 * logging and should not have triggers, as it could disrupt conflict
+	 * logging.
+	 */
+	if (IsConflictLogTableClass(form))
+		ereport(ERROR,
+				(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
+				 errmsg("permission denied: \"%s\" is a conflict log table",
+						rv->relname),
+				 errdetail("Conflict log tables are system-managed tables for logical replication conflicts.")));
+
 	if (!allowSystemTableMods && IsSystemClass(relid, form))
 		ereport(ERROR,
 				(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
diff --git a/src/backend/rewrite/rewriteDefine.c b/src/backend/rewrite/rewriteDefine.c
index 6a223fbeaa4..d00d76613a1 100644
--- a/src/backend/rewrite/rewriteDefine.c
+++ b/src/backend/rewrite/rewriteDefine.c
@@ -262,6 +262,17 @@ DefineQueryRewrite(const char *rulename,
 						RelationGetRelationName(event_relation)),
 				 errdetail_relkind_not_supported(event_relation->rd_rel->relkind)));
 
+	/*
+	 * Conflict log tables are used internally for logical replication conflict
+	 * logging and should not have rules, as it could disrupt conflict logging.
+	 */
+	if (IsConflictLogTableClass(event_relation->rd_rel))
+		ereport(ERROR,
+				(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
+				 errmsg("permission denied: \"%s\" is a conflict log table",
+						RelationGetRelationName(event_relation)),
+				 errdetail("Conflict log tables are system-managed tables for logical replication conflicts.")));
+
 	if (!allowSystemTableMods && IsSystemRelation(event_relation))
 		ereport(ERROR,
 				(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
@@ -772,6 +783,17 @@ RangeVarCallbackForRenameRule(const RangeVar *rv, Oid relid, Oid oldrelid,
 				 errmsg("relation \"%s\" cannot have rules", rv->relname),
 				 errdetail_relkind_not_supported(form->relkind)));
 
+	/*
+	 * Conflict log tables are used internally for logical replication conflict
+	 * logging and should not have rules, as it could disrupt conflict logging.
+	 */
+	if (IsConflictLogTableClass(form))
+		ereport(ERROR,
+				(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
+				 errmsg("permission denied: \"%s\" is a conflict log table",
+						rv->relname),
+				 errdetail("Conflict log tables are system-managed tables for logical replication conflicts.")));
+
 	if (!allowSystemTableMods && IsSystemClass(relid, form))
 		ereport(ERROR,
 				(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
-- 
2.49.0