Implement table partitioning.

Table partitioning is like table inheritance and reuses much of the
existing infrastructure, but there are some important differences.
The parent is called a partitioned table and is always empty; it may
not have indexes or non-inherited constraints, since those make no
sense for a relation with no data of its own.  The children are called
partitions and contain all of the actual data.  Each partition has an
implicit partitioning constraint.  Multiple inheritance is not
allowed, and partitioning and inheritance can't be mixed.  Partitions
can't have extra columns and may not allow nulls unless the parent
does.  Tuples inserted into the parent are automatically routed to the
correct partition, so tuple-routing ON INSERT triggers are not needed.
Tuple routing isn't yet supported for partitions which are foreign
tables, and it doesn't handle updates that cross partition boundaries.

Currently, tables can be range-partitioned or list-partitioned.  List
partitioning is limited to a single column, but range partitioning can
involve multiple columns.  A partitioning "column" can be an
expression.

Because table partitioning is less general than table inheritance, it
is hoped that it will be easier to reason about properties of
partitions, and therefore that this will serve as a better foundation
for a variety of possible optimizations, including query planner
optimizations.  The tuple routing based which this patch does based on
the implicit partitioning constraints is an example of this, but it
seems likely that many other useful optimizations are also possible.

Amit Langote, reviewed and tested by Robert Haas, Ashutosh Bapat,
Amit Kapila, Rajkumar Raghuwanshi, Corey Huinker, Jaime Casanova,
Rushabh Lathia, Erik Rijkers, among others.  Minor revisions by me.

5 files changed, 246 insertions, 0 deletions

diff --git a/src/backend/nodes/copyfuncs.c b/src/backend/nodes/copyfuncs.c
index dd66adb0b24..e30c57e86be 100644
--- a/src/backend/nodes/copyfuncs.c
+++ b/src/backend/nodes/copyfuncs.c
@@ -3030,6 +3030,8 @@ CopyCreateStmtFields(const CreateStmt *from, CreateStmt *newnode)
 	COPY_NODE_FIELD(relation);
 	COPY_NODE_FIELD(tableElts);
 	COPY_NODE_FIELD(inhRelations);
+	COPY_NODE_FIELD(partspec);
+	COPY_NODE_FIELD(partbound);
 	COPY_NODE_FIELD(ofTypename);
 	COPY_NODE_FIELD(constraints);
 	COPY_NODE_FIELD(options);
@@ -4188,6 +4190,70 @@ _copyAlterPolicyStmt(const AlterPolicyStmt *from)
 	return newnode;
 }
 
+static PartitionSpec *
+_copyPartitionSpec(const PartitionSpec *from)
+{
+
+	PartitionSpec *newnode = makeNode(PartitionSpec);
+
+	COPY_STRING_FIELD(strategy);
+	COPY_NODE_FIELD(partParams);
+	COPY_LOCATION_FIELD(location);
+
+	return newnode;
+}
+
+static PartitionElem *
+_copyPartitionElem(const PartitionElem *from)
+{
+	PartitionElem *newnode = makeNode(PartitionElem);
+
+	COPY_STRING_FIELD(name);
+	COPY_NODE_FIELD(expr);
+	COPY_NODE_FIELD(collation);
+	COPY_NODE_FIELD(opclass);
+	COPY_LOCATION_FIELD(location);
+
+	return newnode;
+}
+
+static PartitionBoundSpec *
+_copyPartitionBoundSpec(const PartitionBoundSpec *from)
+{
+	PartitionBoundSpec *newnode = makeNode(PartitionBoundSpec);
+
+	COPY_SCALAR_FIELD(strategy);
+	COPY_NODE_FIELD(listdatums);
+	COPY_NODE_FIELD(lowerdatums);
+	COPY_NODE_FIELD(upperdatums);
+	COPY_LOCATION_FIELD(location);
+
+	return newnode;
+}
+
+static PartitionRangeDatum *
+_copyPartitionRangeDatum(const PartitionRangeDatum *from)
+{
+	PartitionRangeDatum *newnode = makeNode(PartitionRangeDatum);
+
+	COPY_SCALAR_FIELD(infinite);
+	COPY_NODE_FIELD(value);
+	COPY_LOCATION_FIELD(location);
+
+	return newnode;
+}
+
+static PartitionCmd *
+_copyPartitionCmd(const PartitionCmd *from)
+{
+	PartitionCmd *newnode = makeNode(PartitionCmd);
+
+	COPY_NODE_FIELD(name);
+	COPY_NODE_FIELD(bound);
+
+	return newnode;
+}
+
 /* ****************************************************************
  *					pg_list.h copy functions
  * ****************************************************************
@@ -5105,6 +5171,21 @@ copyObject(const void *from)
 		case T_TriggerTransition:
 			retval = _copyTriggerTransition(from);
 			break;
+		case T_PartitionSpec:
+			retval = _copyPartitionSpec(from);
+			break;
+		case T_PartitionElem:
+			retval = _copyPartitionElem(from);
+			break;
+		case T_PartitionBoundSpec:
+			retval = _copyPartitionBoundSpec(from);
+			break;
+		case T_PartitionRangeDatum:
+			retval = _copyPartitionRangeDatum(from);
+			break;
+		case T_PartitionCmd:
+			retval = _copyPartitionCmd(from);
+			break;
 
 			/*
 			 * MISCELLANEOUS NODES
diff --git a/src/backend/nodes/equalfuncs.c b/src/backend/nodes/equalfuncs.c
index cad3aebecd5..b7a109cfb04 100644
--- a/src/backend/nodes/equalfuncs.c
+++ b/src/backend/nodes/equalfuncs.c
@@ -1168,6 +1168,8 @@ _equalCreateStmt(const CreateStmt *a, const CreateStmt *b)
 	COMPARE_NODE_FIELD(relation);
 	COMPARE_NODE_FIELD(tableElts);
 	COMPARE_NODE_FIELD(inhRelations);
+	COMPARE_NODE_FIELD(partspec);
+	COMPARE_NODE_FIELD(partbound);
 	COMPARE_NODE_FIELD(ofTypename);
 	COMPARE_NODE_FIELD(constraints);
 	COMPARE_NODE_FIELD(options);
@@ -2646,6 +2648,59 @@ _equalTriggerTransition(const TriggerTransition *a, const TriggerTransition *b)
 	return true;
 }
 
+static bool
+_equalPartitionSpec(const PartitionSpec *a, const PartitionSpec *b)
+{
+	COMPARE_STRING_FIELD(strategy);
+	COMPARE_NODE_FIELD(partParams);
+	COMPARE_LOCATION_FIELD(location);
+
+	return true;
+}
+
+static bool
+_equalPartitionElem(const PartitionElem *a, const PartitionElem *b)
+{
+	COMPARE_STRING_FIELD(name);
+	COMPARE_NODE_FIELD(expr);
+	COMPARE_NODE_FIELD(collation);
+	COMPARE_NODE_FIELD(opclass);
+	COMPARE_LOCATION_FIELD(location);
+
+	return true;
+}
+
+static bool
+_equalPartitionBoundSpec(const PartitionBoundSpec *a, const PartitionBoundSpec *b)
+{
+	COMPARE_SCALAR_FIELD(strategy);
+	COMPARE_NODE_FIELD(listdatums);
+	COMPARE_NODE_FIELD(lowerdatums);
+	COMPARE_NODE_FIELD(upperdatums);
+	COMPARE_LOCATION_FIELD(location);
+
+	return true;
+}
+
+static bool
+_equalPartitionRangeDatum(const PartitionRangeDatum *a, const PartitionRangeDatum *b)
+{
+	COMPARE_SCALAR_FIELD(infinite);
+	COMPARE_NODE_FIELD(value);
+	COMPARE_LOCATION_FIELD(location);
+
+	return true;
+}
+
+static bool
+_equalPartitionCmd(const PartitionCmd *a, const PartitionCmd *b)
+{
+	COMPARE_NODE_FIELD(name);
+	COMPARE_NODE_FIELD(bound);
+
+	return true;
+}
+
 /*
  * Stuff from pg_list.h
  */
@@ -3402,6 +3457,21 @@ equal(const void *a, const void *b)
 		case T_TriggerTransition:
 			retval = _equalTriggerTransition(a, b);
 			break;
+		case T_PartitionSpec:
+			retval = _equalPartitionSpec(a, b);
+			break;
+		case T_PartitionElem:
+			retval = _equalPartitionElem(a, b);
+			break;
+		case T_PartitionBoundSpec:
+			retval = _equalPartitionBoundSpec(a, b);
+			break;
+		case T_PartitionRangeDatum:
+			retval = _equalPartitionRangeDatum(a, b);
+			break;
+		case T_PartitionCmd:
+			retval = _equalPartitionCmd(a, b);
+			break;
 
 		default:
 			elog(ERROR, "unrecognized node type: %d",
diff --git a/src/backend/nodes/nodeFuncs.c b/src/backend/nodes/nodeFuncs.c
index 399744193c0..973fb152c19 100644
--- a/src/backend/nodes/nodeFuncs.c
+++ b/src/backend/nodes/nodeFuncs.c
@@ -1552,6 +1552,12 @@ exprLocation(const Node *expr)
 			/* just use nested expr's location */
 			loc = exprLocation((Node *) ((const InferenceElem *) expr)->expr);
 			break;
+		case T_PartitionBoundSpec:
+			loc = ((const PartitionBoundSpec *) expr)->location;
+			break;
+		case T_PartitionRangeDatum:
+			loc = ((const PartitionRangeDatum *) expr)->location;
+			break;
 		default:
 			/* for any other node type it's just unknown... */
 			loc = -1;
diff --git a/src/backend/nodes/outfuncs.c b/src/backend/nodes/outfuncs.c
index 748b6879292..0d858f59206 100644
--- a/src/backend/nodes/outfuncs.c
+++ b/src/backend/nodes/outfuncs.c
@@ -2392,6 +2392,8 @@ _outCreateStmtInfo(StringInfo str, const CreateStmt *node)
 	WRITE_NODE_FIELD(relation);
 	WRITE_NODE_FIELD(tableElts);
 	WRITE_NODE_FIELD(inhRelations);
+	WRITE_NODE_FIELD(partspec);
+	WRITE_NODE_FIELD(partbound);
 	WRITE_NODE_FIELD(ofTypename);
 	WRITE_NODE_FIELD(constraints);
 	WRITE_NODE_FIELD(options);
@@ -3277,6 +3279,47 @@ _outForeignKeyCacheInfo(StringInfo str, const ForeignKeyCacheInfo *node)
 		appendStringInfo(str, " %u", node->conpfeqop[i]);
 }
 
+static void
+_outPartitionSpec(StringInfo str, const PartitionSpec *node)
+{
+	WRITE_NODE_TYPE("PARTITIONBY");
+
+	WRITE_STRING_FIELD(strategy);
+	WRITE_NODE_FIELD(partParams);
+	WRITE_LOCATION_FIELD(location);
+}
+
+static void
+_outPartitionElem(StringInfo str, const PartitionElem *node)
+{
+	WRITE_NODE_TYPE("PARTITIONELEM");
+
+	WRITE_STRING_FIELD(name);
+	WRITE_NODE_FIELD(expr);
+	WRITE_NODE_FIELD(collation);
+	WRITE_NODE_FIELD(opclass);
+	WRITE_LOCATION_FIELD(location);
+}
+
+static void
+_outPartitionBoundSpec(StringInfo str, const PartitionBoundSpec *node)
+{
+	WRITE_NODE_TYPE("PARTITIONBOUND");
+
+	WRITE_CHAR_FIELD(strategy);
+	WRITE_NODE_FIELD(listdatums);
+	WRITE_NODE_FIELD(lowerdatums);
+	WRITE_NODE_FIELD(upperdatums);
+}
+
+static void
+_outPartitionRangeDatum(StringInfo str, const PartitionRangeDatum *node)
+{
+	WRITE_NODE_TYPE("PARTRANGEDATUM");
+
+	WRITE_BOOL_FIELD(infinite);
+	WRITE_NODE_FIELD(value);
+}
 
 /*
  * outNode -
@@ -3865,6 +3908,18 @@ outNode(StringInfo str, const void *obj)
 			case T_TriggerTransition:
 				_outTriggerTransition(str, obj);
 				break;
+			case T_PartitionSpec:
+				_outPartitionSpec(str, obj);
+				break;
+			case T_PartitionElem:
+				_outPartitionElem(str, obj);
+				break;
+			case T_PartitionBoundSpec:
+				_outPartitionBoundSpec(str, obj);
+				break;
+			case T_PartitionRangeDatum:
+				_outPartitionRangeDatum(str, obj);
+				break;
 
 			default:
 
diff --git a/src/backend/nodes/readfuncs.c b/src/backend/nodes/readfuncs.c
index 917e6c8a65e..c587d4e1d72 100644
--- a/src/backend/nodes/readfuncs.c
+++ b/src/backend/nodes/readfuncs.c
@@ -2266,6 +2266,36 @@ _readExtensibleNode(void)
 }
 
 /*
+ * _readPartitionBoundSpec
+ */
+static PartitionBoundSpec *
+_readPartitionBoundSpec(void)
+{
+	READ_LOCALS(PartitionBoundSpec);
+
+	READ_CHAR_FIELD(strategy);
+	READ_NODE_FIELD(listdatums);
+	READ_NODE_FIELD(lowerdatums);
+	READ_NODE_FIELD(upperdatums);
+
+	READ_DONE();
+}
+
+/*
+ * _readPartitionRangeDatum
+ */
+static PartitionRangeDatum *
+_readPartitionRangeDatum(void)
+{
+	READ_LOCALS(PartitionRangeDatum);
+
+	READ_BOOL_FIELD(infinite);
+	READ_NODE_FIELD(value);
+
+	READ_DONE();
+}
+
+/*
  * parseNodeString
  *
  * Given a character string representing a node tree, parseNodeString creates
@@ -2497,6 +2527,10 @@ parseNodeString(void)
 		return_value = _readAlternativeSubPlan();
 	else if (MATCH("EXTENSIBLENODE", 14))
 		return_value = _readExtensibleNode();
+	else if (MATCH("PARTITIONBOUND", 14))
+		return_value = _readPartitionBoundSpec();
+	else if (MATCH("PARTRANGEDATUM", 14))
+		return_value = _readPartitionRangeDatum();
 	else
 	{
 		elog(ERROR, "badly formatted node string \"%.32s\"...", token);