From f650f9ced4623d3176a260713ba003a743ddb9d2 Mon Sep 17 00:00:00 2001
From: Onur Tirtir <onurcantirtir@gmail.com>
Date: Tue, 18 Nov 2025 16:04:23 +0300
Subject: [PATCH] fixup! allow "alter table set schema" from any node for
 Postgres tables - citus managed local tables

merge codepaths
---
 .../replicate_none_dist_table_shard.c         | 103 +++++++++---------
 1 file changed, 51 insertions(+), 52 deletions(-)

diff --git a/src/backend/distributed/operations/replicate_none_dist_table_shard.c b/src/backend/distributed/operations/replicate_none_dist_table_shard.c
index 83d660770..2cdf3ebbd 100644
--- a/src/backend/distributed/operations/replicate_none_dist_table_shard.c
+++ b/src/backend/distributed/operations/replicate_none_dist_table_shard.c
@@ -29,6 +29,7 @@
 #include "distributed/worker_protocol.h"
 
 
+static void ReplicateCoordinatorPlacementData(uint64 shardId, List *targetNodeList);
 static void CreateForeignKeysFromReferenceTablesOnShards(Oid noneDistTableId);
 static Oid ForeignConstraintGetReferencingTableId(const char *queryString);
 static void EnsureNoneDistTableWithCoordinatorPlacement(Oid noneDistTableId);
@@ -82,60 +83,14 @@ NoneDistTableReplicateCoordinatorPlacement(Oid noneDistTableId,
 	ShardPlacement *coordinatorPlacement =
 		linitial(ActiveShardPlacementListOnGroup(shardId, COORDINATOR_GROUP_ID));
 
+	/* copy data from coordinator placement to new placements */
+	ReplicateCoordinatorPlacementData(shardId, targetNodeList);
+
 	/*
-	 * The work done below to replicate the shard and
-	 * CreateForeignKeysFromReferenceTablesOnShards() itself need to ignore the
-	 * coordinator shard placement, hence we temporarily delete it using
-	 * DeleteShardPlacementRowGlobally() before moving forward.
+	 * CreateForeignKeysFromReferenceTablesOnShards
+	 * needs to ignore the local placement, hence we temporarily delete it.
 	 */
-	if (IsCoordinator())
-	{
-		/* TODOTASK: maybe remove this codepath? "else" can possibly handle coordinator-placement too */
-
-		/* fetch coordinator placement before deleting it */
-		Oid localPlacementTableId = GetTableLocalShardOid(noneDistTableId, shardId);
-
-		DeleteShardPlacementRowGlobally(coordinatorPlacement->placementId);
-
-		/* and copy data from local placement to new placements */
-		CopyFromLocalTableIntoDistTable(
-			localPlacementTableId, noneDistTableId
-			);
-	}
-	else
-	{
-		DeleteShardPlacementRowGlobally(coordinatorPlacement->placementId);
-
-		List *taskList = NIL;
-		uint64 jobId = INVALID_JOB_ID;
-		uint32 taskId = 0;
-		foreach_declared_ptr(targetNode, targetNodeList)
-		{
-			Task *task = CitusMakeNode(Task);
-			task->jobId = jobId;
-			task->taskId = taskId++;
-			task->taskType = READ_TASK;
-			task->replicationModel = REPLICATION_MODEL_INVALID;
-			char *shardCopyCommand = CreateShardCopyCommand(LoadShardInterval(shardId),
-															targetNode);
-			SetTaskQueryStringList(task, list_make1(shardCopyCommand));
-
-			/* we already verified that coordinator is in the metadata */
-			WorkerNode *coordinatorNode = CoordinatorNodeIfAddedAsWorkerOrError();
-
-			/*
-			 * Need execute the task at the source node as we'll copy the shard
-			 * from there, i.e., the coordinator.
-			 */
-			ShardPlacement *taskPlacement = CitusMakeNode(ShardPlacement);
-			SetPlacementNodeMetadata(taskPlacement, coordinatorNode);
-
-			task->taskPlacementList = list_make1(taskPlacement);
-			taskList = lappend(taskList, task);
-		}
-
-		ExecuteTaskList(ROW_MODIFY_READONLY, taskList);
-	}
+	DeleteShardPlacementRowGlobally(coordinatorPlacement->placementId);
 
 	/*
 	 * CreateShardsOnWorkers only creates the foreign keys where given relation
@@ -229,6 +184,50 @@ NoneDistTableDropCoordinatorPlacementTable(Oid noneDistTableId)
 }
 
 
+/*
+ * ReplicateCoordinatorPlacementData copies data from the coordinator
+ * shard placement to the target nodes.
+ *
+ * Assumes that the shard placements already exist on the coordinator and
+ * target nodes.
+ */
+static void
+ReplicateCoordinatorPlacementData(uint64 shardId, List *targetNodeList)
+{
+	List *taskList = NIL;
+
+	uint64 jobId = INVALID_JOB_ID;
+	uint32 taskId = 0;
+	WorkerNode *targetNode = NULL;
+	foreach_declared_ptr(targetNode, targetNodeList)
+	{
+		Task *task = CitusMakeNode(Task);
+		task->jobId = jobId;
+		task->taskId = taskId++;
+		task->taskType = READ_TASK;
+		task->replicationModel = REPLICATION_MODEL_INVALID;
+		char *shardCopyCommand = CreateShardCopyCommand(LoadShardInterval(shardId),
+														targetNode);
+		SetTaskQueryStringList(task, list_make1(shardCopyCommand));
+
+		/* we already verified that coordinator is in the metadata */
+		WorkerNode *coordinatorNode = CoordinatorNodeIfAddedAsWorkerOrError();
+
+		/*
+		 * Need execute the task at the source node as we'll copy the shard
+		 * from there, i.e., the coordinator.
+		 */
+		ShardPlacement *taskPlacement = CitusMakeNode(ShardPlacement);
+		SetPlacementNodeMetadata(taskPlacement, coordinatorNode);
+
+		task->taskPlacementList = list_make1(taskPlacement);
+		taskList = lappend(taskList, task);
+	}
+
+	ExecuteTaskList(ROW_MODIFY_READONLY, taskList);
+}
+
+
 /*
  * CreateForeignKeysFromReferenceTablesOnShards creates foreign keys on shards
  * where given none-distributed table is the referenced table and the referencing