Using replication origin remote commands for shard moves/splits.

src/backend/distributed/operations/worker_shard_copy.c

@@ -32,6 +32,17 @@
  * argument to the copy callback.
  */
 static StringInfo LocalCopyBuffer;
+#define CDC_REPLICATION_ORIGIN_CREATE_IF_NOT_EXISTS_CMD \
+	"SELECT  pg_catalog.pg_replication_origin_create('citus_cdc') \
+	where (select pg_catalog.pg_replication_origin_oid('citus_cdc')) IS NULL;"
+
+#define CDC_REPLICATION_ORIGIN_SESION_SETUP_CMD \
+	"SELECT pg_catalog.pg_replication_origin_session_setup('citus_cdc') \
+	where pg_catalog.pg_replication_origin_session_is_setup()='f';"
+
+#define CDC_REPLICATION_ORIGIN_SESION_RESET_CMD \
+	"SELECT pg_catalog.pg_replication_origin_session_reset() \
+	where pg_catalog.pg_replication_origin_session_is_setup()='t';"
 
 typedef struct ShardCopyDestReceiver
 {
@@ -80,7 +91,10 @@ static int ReadFromLocalBufferCallback(void *outBuf, int minRead, int maxRead);
 static void LocalCopyToShard(ShardCopyDestReceiver *copyDest, CopyOutState
 							 localCopyOutState);
 static void ConnectToRemoteAndStartCopy(ShardCopyDestReceiver *copyDest);
-static void SetupReplicationOrigin(RepOriginId nodeId);
+
+static void CreateReplicationOriginIfNotExists(ShardCopyDestReceiver *dest);
+static void SetupReplicationOriginSessionIfNotSetupAlready(MultiConnection *connection);
+static void ResetReplicationOriginSessionIfSetupAlready(MultiConnection *connection);
 
 static bool
 CanUseLocalCopy(uint32_t destinationNodeId)
@@ -89,6 +103,30 @@ CanUseLocalCopy(uint32_t destinationNodeId)
 	return GetLocalNodeId() == (int32) destinationNodeId;
 }
 
+/*
+ * SetupReplicationOriginSessionIfNotSetupAlready sets up the replication origin session
+ * if it is not already setup.
+ */
+ static void SetupReplicationOriginSessionIfNotSetupAlready(MultiConnection *connection) {
+	/* Setup replication Origin if not setup already */
+	if (!SendRemoteCommand(connection, CDC_REPLICATION_ORIGIN_SESION_SETUP_CMD))
+	{
+		ReportConnectionError(connection, ERROR);
+	}
+	ForgetResults(connection);
+}
+
+/*
+ * ResetReplicationOriginSessionIfSetupAlready resets the replication origin session
+ * if it has been setup currently.
+ */
+static void ResetReplicationOriginSessionIfSetupAlready(MultiConnection *connection) {
+	if (!SendRemoteCommand(connection, CDC_REPLICATION_ORIGIN_SESION_RESET_CMD))
+	{
+		ReportConnectionError(connection, ERROR);
+	}
+	ForgetResults(connection);
+}
 
 /* Connect to node with source shard and trigger copy start.  */
 static void
@@ -105,10 +143,13 @@ ConnectToRemoteAndStartCopy(ShardCopyDestReceiver *copyDest)
 														 NULL /* database (current) */);
 	ClaimConnectionExclusively(copyDest->connection);
 
+	/* Setup Replication Origin Session if not setup already for 
+	avoiding publication of events more than once. */
+	SetupReplicationOriginSessionIfNotSetupAlready(copyDest->connection);
+
 	StringInfo copyStatement = ConstructShardCopyStatement(
 		copyDest->destinationShardFullyQualifiedName,
 		copyDest->copyOutState->binary);
-
 	if (!SendRemoteCommand(copyDest->connection, copyStatement->data))
 	{
 		ReportConnectionError(copyDest->connection, ERROR);
@@ -154,7 +195,9 @@ CreateShardCopyDestReceiver(EState *executorState,
 	return (DestReceiver *) copyDest;
 }
 
+
 #define InvalidRepOriginId 0
+
 /*
  * ShardCopyDestReceiverReceive implements the receiveSlot function of
  * ShardCopyDestReceiver. It takes a TupleTableSlot and sends the contents to
@@ -234,27 +277,6 @@ ShardCopyDestReceiverReceive(TupleTableSlot *slot, DestReceiver *dest)
 	return true;
 }
 
-static void 
-SetupReplicationOrigin(RepOriginId nodeId) {
-	RepOriginId originid = InvalidRepOriginId;
-	XLogRecPtr	origin_startpos = InvalidXLogRecPtr;
-	//Check if there is a replication origin session already active.
-	if (replorigin_session_origin == InvalidRepOriginId) {
-		//Lookup the replication origin and create it if it does not exist.
-		char originname[NAMEDATALEN];
-		snprintf(originname, sizeof(originname), "pg_%u",nodeId);
-		originid = replorigin_by_name(originname, true);
-		if (originid == InvalidRepOriginId) {
-			originid = replorigin_create(originname);
-		}
-		//Setup the replication origin session.
-		replorigin_session_setup(originid);
-		replorigin_session_origin = originid;
-		origin_startpos = replorigin_session_get_progress(false);
-		//elog(LOG, "!!!! Citus: ShardCopyDestReceiverReceive replorigin_session_origin %d", replorigin_session_origin);
-	}
-}
-
 
 /*
  * ShardCopyDestReceiverStartup implements the rStartup interface of ShardCopyDestReceiver.
@@ -282,7 +304,26 @@ ShardCopyDestReceiverStartup(DestReceiver *dest, int operation, TupleDesc
 	copyDest->columnOutputFunctions = ColumnOutputFunctions(inputTupleDescriptor,
 															copyOutState->binary);
 	copyDest->copyOutState = copyOutState;
-	SetupReplicationOrigin(copyDest->destinationNodeId);
+	CreateReplicationOriginIfNotExists(copyDest);
+}
+
+
+static void
+CreateReplicationOriginIfNotExists(ShardCopyDestReceiver *dest)
+{
+	int connectionFlags = OUTSIDE_TRANSACTION;
+	char *currentUser = CurrentUserName();
+	WorkerNode *workerNode = FindNodeWithNodeId(dest->destinationNodeId,
+												false /* missingOk */);
+	MultiConnection *connection = GetNodeUserDatabaseConnection(connectionFlags,
+																workerNode->workerName,
+																workerNode->workerPort,
+																currentUser,
+																NULL /* database (current) */);
+	ClaimConnectionExclusively(connection);
+	ExecuteCriticalRemoteCommand(connection,
+								 CDC_REPLICATION_ORIGIN_CREATE_IF_NOT_EXISTS_CMD);
+	CloseConnection(connection);
 }
 
 
@@ -341,6 +382,11 @@ ShardCopyDestReceiverShutdown(DestReceiver *dest)
 
 		PQclear(result);
 		ForgetResults(copyDest->connection);
+
+		/*Reset Replication Origin. */
+		ExecuteCriticalRemoteCommand(copyDest->connection,
+									 CDC_REPLICATION_ORIGIN_SESION_RESET_CMD);
+
 		CloseConnection(copyDest->connection);
 	}
 }

src/backend/distributed/shardsplit/shardsplit_decoder.c

@@ -13,6 +13,7 @@
 #include "distributed/worker_shard_visibility.h"
 #include "distributed/worker_protocol.h"
 #include "distributed/listutils.h"
+#include "distributed/metadata/distobject.h"
 #include "replication/logical.h"
 #include "utils/typcache.h"
 #include "utils/lsyscache.h"
@@ -39,15 +40,15 @@ static Oid FindTargetRelationOid(Relation sourceShardRelation,
 static HeapTuple GetTupleForTargetSchema(HeapTuple sourceRelationTuple,
 										 TupleDesc sourceTupleDesc,
 										 TupleDesc targetTupleDesc);
-static bool
+static bool replication_origin_filter_cb(LogicalDecodingContext *ctx, RepOriginId origin_id);
-cdc_origin_filter(LogicalDecodingContext *ctx, RepOriginId origin_id);
 
-static bool 
+static bool PublishChangesIfCdcSlot(LogicalDecodingContext *ctx, ReorderBufferTXN *txn,
-is_cdc_replication_slot(LogicalDecodingContext *ctx);
-
-bool
-handle_cdc_changes(LogicalDecodingContext *ctx, ReorderBufferTXN *txn,
 						Relation relation, ReorderBufferChange *change);
+
+/* used in the replication_origin_filter_cb function. */
+#define InvalidRepOriginId 0
+#define CITUS_CDC_SLOT_NAME "citus_cdc_slot"
+
 /*
  * Postgres uses 'pgoutput' as default plugin for logical replication.
  * We want to reuse Postgres pgoutput's functionality as much as possible.
@@ -69,70 +70,71 @@ _PG_output_plugin_init(OutputPluginCallbacks *cb)
 
 	/* ask the output plugin to fill the callback struct */
 	plugin_init(cb);
+
 	/* actual pgoutput callback will be called with the appropriate destination shard */
 	pgoutputChangeCB = cb->change_cb;
 	cb->change_cb = split_change_cb;
-	cb->filter_by_origin_cb = cdc_origin_filter;
+	cb->filter_by_origin_cb = replication_origin_filter_cb;
 }
 
-#define InvalidRepOriginId 0
 
 /*
- * cdc_origin_filter is called for each change. If the change is not
+ * replication_origin_filter_cb call back function filters out publication of changes
- * originated from the CDC replication slot, we return false to skip
+ * originated from any other node other than the current node. This is
- * the change.
+ * identified by the "origin_id" of the changes. The origin_id is set to
+ * a non-zero value in the origin node as part of WAL replication.
  */
  static bool
-cdc_origin_filter(LogicalDecodingContext *ctx, RepOriginId origin_id)
+replication_origin_filter_cb(LogicalDecodingContext *ctx, RepOriginId origin_id)
 {
 	if (origin_id != InvalidRepOriginId)
 	{
-		elog(LOG,"!!!! cdc_origin_filter: filtering because origin_id: %d \n",origin_id);
 		return true;
 	}
-	//elog(LOG,"!!!! cdc_origin_filter: NOT filtering because origin_id: %d \n",origin_id);
 	return false;
 }
 
+/* 
+ * PublishChangesIfCdcSlot checks if the current slot is a CDC slot. If so, it publishes
+ * the changes as the change for the distributed table instead of shard. 
+ * If not, it returns false. It also skips the Citus metadata tables.
+ */
 static bool
-is_cdc_replication_slot(LogicalDecodingContext *ctx) {
+PublishChangesIfCdcSlot(LogicalDecodingContext *ctx, ReorderBufferTXN *txn,
+				   Relation relation, ReorderBufferChange *change)
+{
 	char *replicationSlotName = ctx->slot->data.name.data;
-	//elog(LOG,"is_cdc_replication_slot: replicationSlotName %s", replicationSlotName);
+	/* Check if the replication slot is CITUS_CDC_SLOT*/
-	return (replicationSlotName != NULL && strcmp(replicationSlotName,"cdc")== 0);
+	if (replicationSlotName != NULL && strcmp(replicationSlotName, CITUS_CDC_SLOT_NAME) == 0)
+	{
+		/* Skip publishing changes for Citus metadata tables*/
+		ObjectAddress objectAdress = {RelationRelationId, relation->rd_id, 0};
+		if (IsObjectAddressOwnedByCitus(&objectAdress))    
+		{
+			return true;
 		}   
-
+		/* Check if this change is for a shard in distributed table. */
-bool
+		if (RelationIsAKnownShard(relation->rd_id))
-handle_cdc_changes(LogicalDecodingContext *ctx, ReorderBufferTXN *txn,
+		{
-				Relation relation, ReorderBufferChange *change) {
-	bool is_cdc_translated_to_distribution_table = false;
-	if (is_cdc_replication_slot(ctx)) {
-		// Check if it is a change in a Shard table
-		if (RelationIsAKnownShard(relation->rd_id)) {
-			//Oid shardRelationId = relation->rd_id;
 			char *shardRelationName = RelationGetRelationName(relation);
 			uint64 shardId = ExtractShardIdFromTableName(shardRelationName, true);
 			if (shardId != INVALID_SHARD_ID)
 			{
-				// try to get the distributed relation id for the shard
+				/* try to get the distributed relation id for the shard */
 				Oid distributedRelationId = RelationIdForShard(shardId);
 				if (OidIsValid(distributedRelationId))
 				{
-					char* relationName = get_rel_name(distributedRelationId);
+					relation = RelationIdGetRelation(distributedRelationId);
-					//elog(LOG,"changing to distributed relation name:%s id:%d ", relationName, distributedRelationId); 
-					Relation distributedRelation = RelationIdGetRelation(distributedRelationId);
-					pgoutputChangeCB(ctx, txn, distributedRelation, change);
-					is_cdc_translated_to_distribution_table = true;
 				}
 			}
 		}
-		if (!is_cdc_translated_to_distribution_table) {
 		pgoutputChangeCB(ctx, txn, relation, change);
-		}		
 		return true;
 	} 
 	return false;
 }
 
+
 /*
  * split_change function emits the incoming tuple change
  * to the appropriate destination shard.
@@ -141,11 +143,11 @@ static void
 split_change_cb(LogicalDecodingContext *ctx, ReorderBufferTXN *txn,
 				Relation relation, ReorderBufferChange *change)
 {
-	//elog(LOG,"Citus split_change_cb called");
+	if (!is_publishable_relation(relation))
-	if (handle_cdc_changes(ctx,txn,relation,change)) {
+	{
 		return;
 	}
-	if (!is_publishable_relation(relation))
+	if (PublishChangesIfCdcSlot(ctx, txn, relation, change))
 	{
 		return;
 	}
@@ -274,6 +276,7 @@ split_change_cb(LogicalDecodingContext *ctx, ReorderBufferTXN *txn,
 	RelationClose(targetRelation);
 }
 
+
 /*
  * FindTargetRelationOid returns the destination relation Oid for the incoming
  * tuple.