Add ShardPlacement fields required for colocated placement connection mapping.

src/backend/distributed/utils/citus_outfuncs.c

@@ -473,6 +473,10 @@ OutShardPlacement(OUTFUNC_ARGS)
 	WRITE_ENUM_FIELD(shardState, RelayFileState);
 	WRITE_STRING_FIELD(nodeName);
 	WRITE_UINT_FIELD(nodePort);
+	/* so we can deal with 0 */
+	WRITE_INT_FIELD(partitionMethod);
+	WRITE_UINT_FIELD(colocationGroupId);
+	WRITE_UINT_FIELD(representativeValue);
 }
 
 

src/backend/distributed/utils/citus_readfuncs.c

@@ -268,6 +268,10 @@ ReadShardPlacement(READFUNC_ARGS)
 	READ_ENUM_FIELD(shardState, RelayFileState);
 	READ_STRING_FIELD(nodeName);
 	READ_UINT_FIELD(nodePort);
+	/* so we can deal with 0 */
+	READ_INT_FIELD(partitionMethod);
+	READ_UINT_FIELD(colocationGroupId);
+	READ_UINT_FIELD(representativeValue);
 
 	READ_DONE();
 }

src/backend/distributed/utils/metadata_cache.c

@@ -703,9 +703,31 @@ BuildCachedShardList(DistTableCacheEntry *cacheEntry)
 		foreach(placementCell, placementList)
 		{
 			ShardPlacement *srcPlacement = (ShardPlacement *) lfirst(placementCell);
+			ShardPlacement *dstPlacement = &placementArray[placementOffset];
 
-			CopyShardPlacement(srcPlacement, &placementArray[placementOffset]);
+			CopyShardPlacement(srcPlacement, dstPlacement);
 
+			/* fill in remaining fields */
+			Assert(cacheEntry->partitionMethod != 0);
+			dstPlacement->partitionMethod = cacheEntry->partitionMethod;
+			dstPlacement->colocationGroupId = cacheEntry->colocationId;
+			if (cacheEntry->partitionMethod == DISTRIBUTE_BY_HASH)
+			{
+				Assert(shardInterval->minValueExists);
+				Assert(shardInterval->valueTypeId == INT4OID);
+
+				/*
+				 * Use the lower boundary of the interval's range to identify
+				 * it for colocation purposes. That remains meaningful even if
+				 * a concurrent session splits a shard.
+				 */
+				dstPlacement->representativeValue =
+					DatumGetInt32(shardInterval->minValue);
+			}
+			else
+			{
+				dstPlacement->representativeValue = 0;
+			}
 			placementOffset++;
 		}
 		MemoryContextSwitchTo(oldContext);

src/include/distributed/master_metadata_utility.h

@@ -53,6 +53,9 @@ typedef struct ShardPlacement
 	RelayFileState shardState;
 	char *nodeName;
 	uint32 nodePort;
+	char partitionMethod;
+	uint32 colocationGroupId;
+	uint32 representativeValue;
 } ShardPlacement;