Add nodeId to shardPlacements and use it for shard placement comparisons

Before this commit, shardPlacements were identified with shardId, nodeName
and nodeport. Instead of using nodeName and nodePort, we now use nodeId
since it apparently has performance benefits in several places in the
code.

src/backend/distributed/commands/multi_copy.c

@@ -1051,6 +1051,13 @@ RemoteFinalizedShardPlacementList(uint64 shardId)
 			shardPlacement->nodeName = nodeName;
 			shardPlacement->nodePort = nodePort;
 
+			/*
+			 * We cannot know the nodeId, but it is not necessary at this point either.
+			 * This is only used to to look up the connection for a group of co-located
+			 * placements, but append-distributed tables are never co-located.
+			 */
+			shardPlacement->nodeId = -1;
+
 			finalizedPlacementList = lappend(finalizedPlacementList, shardPlacement);
 		}
 	}

src/backend/distributed/connection/placement_connection.c

@@ -133,8 +133,7 @@ static HTAB *ConnectionPlacementHash;
 typedef struct ColocatedPlacementsHashKey
 {
 	/* to identify host - database can't differ */
-	char nodeName[MAX_NODE_LENGTH];
+	int nodeId;
-	uint32 nodePort;
 
 	/* colocation group, or invalid */
 	uint32 colocationGroupId;
@@ -689,8 +688,7 @@ FindOrCreatePlacementEntry(ShardPlacement *placement)
 			ColocatedPlacementsHashKey key;
 			ColocatedPlacementsHashEntry *colocatedEntry = NULL;
 
-			strlcpy(key.nodeName, placement->nodeName, MAX_NODE_LENGTH);
+			key.nodeId = placement->nodeId;
-			key.nodePort = placement->nodePort;
 			key.colocationGroupId = placement->colocationGroupId;
 			key.representativeValue = placement->representativeValue;
 
@@ -1149,8 +1147,7 @@ ColocatedPlacementsHashHash(const void *key, Size keysize)
 	ColocatedPlacementsHashKey *entry = (ColocatedPlacementsHashKey *) key;
 	uint32 hash = 0;
 
-	hash = string_hash(entry->nodeName, NAMEDATALEN);
+	hash = hash_uint32(entry->nodeId);
-	hash = hash_combine(hash, hash_uint32(entry->nodePort));
 	hash = hash_combine(hash, hash_uint32(entry->colocationGroupId));
 	hash = hash_combine(hash, hash_uint32(entry->representativeValue));
 
@@ -1164,8 +1161,7 @@ ColocatedPlacementsHashCompare(const void *a, const void *b, Size keysize)
 	ColocatedPlacementsHashKey *ca = (ColocatedPlacementsHashKey *) a;
 	ColocatedPlacementsHashKey *cb = (ColocatedPlacementsHashKey *) b;
 
-	if (strncmp(ca->nodeName, cb->nodeName, MAX_NODE_LENGTH) != 0 ||
+	if (ca->nodeId != cb->nodeId ||
-		ca->nodePort != cb->nodePort ||
 		ca->colocationGroupId != cb->colocationGroupId ||
 		ca->representativeValue != cb->representativeValue)
 	{

src/backend/distributed/planner/multi_physical_planner.c

@@ -2552,8 +2552,7 @@ CoPlacedShardIntervals(ShardInterval *firstInterval, ShardInterval *secondInterv
 		ShardPlacement *secondShardPlacement = (ShardPlacement *) lfirst(
 			secondShardPlacementCell);
 
-		if (strcmp(firstShardPlacement->nodeName, secondShardPlacement->nodeName) != 0 ||
+		if (firstShardPlacement->nodeId != secondShardPlacement->nodeId)
-			firstShardPlacement->nodePort != secondShardPlacement->nodePort)
 		{
 			return false;
 		}
@@ -5375,6 +5374,7 @@ AssignDualHashTaskList(List *taskList)
 			ShardPlacement *taskPlacement = CitusMakeNode(ShardPlacement);
 			taskPlacement->nodeName = pstrdup(workerNode->workerName);
 			taskPlacement->nodePort = workerNode->workerPort;
+			taskPlacement->nodeId = workerNode->nodeId;
 
 			taskPlacementList = lappend(taskPlacementList, taskPlacement);
 		}

src/backend/distributed/planner/multi_router_planner.c

@@ -2027,6 +2027,7 @@ PlanRouterQuery(Query *originalQuery,
 				(ShardPlacement *) CitusMakeNode(ShardPlacement);
 			dummyPlacement->nodeName = workerNode->workerName;
 			dummyPlacement->nodePort = workerNode->workerPort;
+			dummyPlacement->nodeId = workerNode->nodeId;
 			dummyPlacement->groupId = workerNode->groupId;
 
 			workerList = lappend(workerList, dummyPlacement);

src/backend/distributed/utils/citus_copyfuncs.c

@@ -200,6 +200,7 @@ CopyNodeShardPlacement(COPYFUNC_ARGS)
 	COPY_SCALAR_FIELD(groupId);
 	COPY_STRING_FIELD(nodeName);
 	COPY_SCALAR_FIELD(nodePort);
+	COPY_SCALAR_FIELD(nodeId);
 	COPY_SCALAR_FIELD(partitionMethod);
 	COPY_SCALAR_FIELD(colocationGroupId);
 	COPY_SCALAR_FIELD(representativeValue);

src/backend/distributed/utils/citus_outfuncs.c

@@ -405,6 +405,7 @@ OutShardPlacement(OUTFUNC_ARGS)
 	WRITE_INT_FIELD(groupId);
 	WRITE_STRING_FIELD(nodeName);
 	WRITE_UINT_FIELD(nodePort);
+	WRITE_INT_FIELD(nodeId);
 	/* so we can deal with 0 */
 	WRITE_INT_FIELD(partitionMethod);
 	WRITE_UINT_FIELD(colocationGroupId);

src/backend/distributed/utils/citus_readfuncs.c

@@ -315,6 +315,7 @@ ReadShardPlacement(READFUNC_ARGS)
 	READ_INT_FIELD(groupId);
 	READ_STRING_FIELD(nodeName);
 	READ_UINT_FIELD(nodePort);
+	READ_INT_FIELD(nodeId);
 	/* so we can deal with 0 */
 	READ_INT_FIELD(partitionMethod);
 	READ_UINT_FIELD(colocationGroupId);

src/backend/distributed/utils/colocation_utils.c

@@ -420,25 +420,12 @@ CompareShardPlacementsByNode(const void *leftElement, const void *rightElement)
 	const ShardPlacement *leftPlacement = *((const ShardPlacement **) leftElement);
 	const ShardPlacement *rightPlacement = *((const ShardPlacement **) rightElement);
 
-	char *leftNodeName = leftPlacement->nodeName;
-	char *rightNodeName = rightPlacement->nodeName;
-
-	uint32 leftNodePort = leftPlacement->nodePort;
-	uint32 rightNodePort = rightPlacement->nodePort;
-
-	/* first compare node names */
-	int nodeNameCompare = strncmp(leftNodeName, rightNodeName, WORKER_LENGTH);
-	if (nodeNameCompare != 0)
-	{
-		return nodeNameCompare;
-	}
-
 	/* if node names are same, check node ports */
-	if (leftNodePort < rightNodePort)
+	if (leftPlacement->nodeId < rightPlacement->nodeId)
 	{
 		return -1;
 	}
-	else if (leftNodePort > rightNodePort)
+	else if (leftPlacement->nodeId > rightPlacement->nodeId)
 	{
 		return 1;
 	}

src/backend/distributed/utils/metadata_cache.c

@@ -526,6 +526,7 @@ ResolveGroupShardPlacement(GroupShardPlacement *groupShardPlacement,
 
 	shardPlacement->nodeName = pstrdup(workerNode->workerName);
 	shardPlacement->nodePort = workerNode->workerPort;
+	shardPlacement->nodeId = workerNode->nodeId;
 
 	/* fill in remaining fields */
 	Assert(tableEntry->partitionMethod != 0);

src/include/distributed/master_metadata_utility.h

@@ -99,6 +99,7 @@ typedef struct ShardPlacement
 	/* the rest of the fields aren't from pg_dist_placement */
 	char *nodeName;
 	uint32 nodePort;
+	int nodeId;
 	char partitionMethod;
 	uint32 colocationGroupId;
 	uint32 representativeValue;