Modified files for MERGE

src/include/nodes/execnodes.h

@@ -360,8 +360,17 @@ typedef struct JunkFilter
 	AttrNumber *jf_cleanMap;
 	TupleTableSlot *jf_resultSlot;
 	AttrNumber	jf_junkAttNo;
+	AttrNumber	jf_otherJunkAttNo;
 } JunkFilter;
 
+typedef struct MergeState
+{
+	/* List of MERGE MATCHED action states */
+	List		   *matchedActionStates;
+	/* List of MERGE NOT MATCHED action states */
+	List		   *notMatchedActionStates;
+} MergeState;
+
 /*
  * OnConflictSetState
  *
@@ -452,8 +461,38 @@ typedef struct ResultRelInfo
 
 	/* relation descriptor for root partitioned table */
 	Relation	ri_PartitionRoot;
+
+	int			ri_PartitionLeafIndex;
+	/* for running MERGE on this result relation */
+	MergeState *ri_mergeState;
+
+	/*
+	 * While executing MERGE, the target relation is processed twice; once
+	 * as a target relation and once to run a join between the target and the
+	 * source. We generate two different RTEs for these two purposes, one with
+	 * rte->inh set to false and other with rte->inh set to true.
+	 *
+	 * Since the plan re-evaluated by EvalPlanQual uses the join RTE, we must
+	 * install the updated tuple in the scan corresponding to that RTE. The
+	 * following member tracks the index of the second RTE for EvalPlanQual
+	 * purposes. ri_mergeTargetRTI is non-zero only when MERGE is in-progress.
+	 * We use ri_mergeTargetRTI to run EvalPlanQual for MERGE and
+	 * ri_RangeTableIndex elsewhere.
+	 */
+	Index		ri_mergeTargetRTI;
 } ResultRelInfo;
 
+/*
+ * Get the Range table index for EvalPlanQual.
+ *
+ * We use the ri_mergeTargetRTI if set, otherwise use ri_RangeTableIndex.
+ * ri_mergeTargetRTI should really be ever set iff we're running MERGE.
+ */
+#define GetEPQRangeTableIndex(r) \
+	(((r)->ri_mergeTargetRTI > 0)  \
+	 ? (r)->ri_mergeTargetRTI \
+	 : (r)->ri_RangeTableIndex)
+
 /* ----------------
  *	  EState information
  *
@@ -966,6 +1005,11 @@ typedef struct PlanState
 		if (((PlanState *)(node))->instrument) \
 			((PlanState *)(node))->instrument->nfiltered2 += (delta); \
 	} while(0)
+#define InstrCountFiltered3(node, delta) \
+	do { \
+		if (((PlanState *)(node))->instrument) \
+			((PlanState *)(node))->instrument->nfiltered3 += (delta); \
+	} while(0)
 
 /*
  * EPQState is state for executing an EvalPlanQual recheck on a candidate
@@ -1012,6 +1056,20 @@ typedef struct ProjectSetState
 	MemoryContext argcontext;	/* context for SRF arguments */
 } ProjectSetState;
 
+/* ----------------
+ *	 MergeActionState information
+ * ----------------
+ */
+typedef struct MergeActionState
+{
+	NodeTag		type;
+	bool		matched;		/* true=MATCHED, false=NOT MATCHED */
+	ExprState  *whenqual;		/* WHEN AND conditions */
+	CmdType		commandType;	/* INSERT/UPDATE/DELETE/DO NOTHING */
+	ProjectionInfo *proj;		/* tuple projection info */
+	TupleDesc	tupDesc;		/* tuple descriptor for projection */
+} MergeActionState;
+
 /* ----------------
  *	 ModifyTableState information
  * ----------------
@@ -1019,7 +1077,7 @@ typedef struct ProjectSetState
 typedef struct ModifyTableState
 {
 	PlanState	ps;				/* its first field is NodeTag */
-	CmdType		operation;		/* INSERT, UPDATE, or DELETE */
+	CmdType		operation;		/* INSERT, UPDATE, DELETE or MERGE */
 	bool		canSetTag;		/* do we set the command tag/es_processed? */
 	bool		mt_done;		/* are we done? */
 	PlanState **mt_plans;		/* subplans (one per target rel) */
@@ -1035,6 +1093,8 @@ typedef struct ModifyTableState
 	List	   *mt_excludedtlist;	/* the excluded pseudo relation's tlist  */
 	TupleTableSlot *mt_conflproj;	/* CONFLICT ... SET ... projection target */
 
+	TupleTableSlot *mt_mergeproj;	/* MERGE action projection target */
+
 	/* Tuple-routing support info */
 	struct PartitionTupleRouting *mt_partition_tuple_routing;
 
@@ -1046,6 +1106,9 @@ typedef struct ModifyTableState
 
 	/* Per plan map for tuple conversion from child to root */
 	TupleConversionMap **mt_per_subplan_tupconv_maps;
+
+	/* Flags showing which subcommands are present INS/UPD/DEL/DO NOTHING */
+	int			mt_merge_subcommands;
 } ModifyTableState;
 
 /* ----------------

src/include/nodes/nodes.h

@@ -97,6 +97,7 @@ typedef enum NodeTag
 	T_PlanState,
 	T_ResultState,
 	T_ProjectSetState,
+	T_MergeActionState,
 	T_ModifyTableState,
 	T_AppendState,
 	T_MergeAppendState,
@@ -308,6 +309,8 @@ typedef enum NodeTag
 	T_InsertStmt,
 	T_DeleteStmt,
 	T_UpdateStmt,
+	T_MergeStmt,
+	T_MergeAction,
 	T_SelectStmt,
 	T_AlterTableStmt,
 	T_AlterTableCmd,
@@ -657,7 +660,8 @@ typedef enum CmdType
 	CMD_SELECT,					/* select stmt */
 	CMD_UPDATE,					/* update stmt */
 	CMD_INSERT,					/* insert stmt */
-	CMD_DELETE,
+	CMD_DELETE,					/* delete stmt */
+	CMD_MERGE,					/* merge stmt */
 	CMD_UTILITY,				/* cmds like create, destroy, copy, vacuum,
 								 * etc. */
 	CMD_NOTHING					/* dummy command for instead nothing rules

src/include/nodes/parsenodes.h

@@ -38,7 +38,7 @@ typedef enum OverridingKind
 typedef enum QuerySource
 {
 	QSRC_ORIGINAL,				/* original parsetree (explicit query) */
-	QSRC_PARSER,				/* added by parse analysis (now unused) */
+	QSRC_PARSER,				/* added by parse analysis in MERGE */
 	QSRC_INSTEAD_RULE,			/* added by unconditional INSTEAD rule */
 	QSRC_QUAL_INSTEAD_RULE,		/* added by conditional INSTEAD rule */
 	QSRC_NON_INSTEAD_RULE		/* added by non-INSTEAD rule */
@@ -107,7 +107,7 @@ typedef struct Query
 {
 	NodeTag		type;
 
-	CmdType		commandType;	/* select|insert|update|delete|utility */
+	CmdType		commandType;	/* select|insert|update|delete|merge|utility */
 
 	QuerySource querySource;	/* where did I come from? */
 
@@ -118,7 +118,7 @@ typedef struct Query
 	Node	   *utilityStmt;	/* non-null if commandType == CMD_UTILITY */
 
 	int			resultRelation; /* rtable index of target relation for
-								 * INSERT/UPDATE/DELETE; 0 for SELECT */
+								 * INSERT/UPDATE/DELETE/MERGE; 0 for SELECT */
 
 	bool		hasAggs;		/* has aggregates in tlist or havingQual */
 	bool		hasWindowFuncs; /* has window functions in tlist */
@@ -169,6 +169,9 @@ typedef struct Query
 	List	   *withCheckOptions;	/* a list of WithCheckOption's, which are
 									 * only added during rewrite and therefore
 									 * are not written out as part of Query. */
+	int			mergeTarget_relation;
+	List	   *mergeSourceTargetList;
+	List	   *mergeActionList;	/* list of actions for MERGE (only) */
 
 	/*
 	 * The following two fields identify the portion of the source text string
@@ -1128,7 +1131,9 @@ typedef enum WCOKind
 	WCO_VIEW_CHECK,				/* WCO on an auto-updatable view */
 	WCO_RLS_INSERT_CHECK,		/* RLS INSERT WITH CHECK policy */
 	WCO_RLS_UPDATE_CHECK,		/* RLS UPDATE WITH CHECK policy */
-	WCO_RLS_CONFLICT_CHECK		/* RLS ON CONFLICT DO UPDATE USING policy */
+	WCO_RLS_CONFLICT_CHECK,		/* RLS ON CONFLICT DO UPDATE USING policy */
+	WCO_RLS_MERGE_UPDATE_CHECK, /* RLS MERGE UPDATE USING policy */
+	WCO_RLS_MERGE_DELETE_CHECK	/* RLS MERGE DELETE USING policy */
 } WCOKind;
 
 typedef struct WithCheckOption
@@ -1503,6 +1508,30 @@ typedef struct UpdateStmt
 	WithClause *withClause;		/* WITH clause */
 } UpdateStmt;
 
+/* ----------------------
+ *		Merge Statement
+ * ----------------------
+ */
+typedef struct MergeStmt
+{
+	NodeTag		type;
+	RangeVar   *relation;			/* target relation to merge into */
+	Node	   *source_relation;	/* source relation */
+	Node	   *join_condition; /* join condition between source and target */
+	List	   *mergeActionList;	/* list of MergeAction(s) */
+} MergeStmt;
+
+typedef struct MergeAction
+{
+	NodeTag		type;
+	bool		matched;		/* true=MATCHED, false=NOT MATCHED */
+	Node	   *condition;		/* WHEN AND conditions (raw parser) */
+	Node	   *qual;			/* transformed WHEN AND conditions */
+	CmdType		commandType;	/* INSERT/UPDATE/DELETE/DO NOTHING */
+	Node	   *stmt;			/* T_UpdateStmt etc */
+	List	   *targetList;		/* the target list (of ResTarget) */
+} MergeAction;
+
 /* ----------------------
  *		Select Statement
  *

src/include/nodes/plannodes.h

@@ -18,6 +18,7 @@
 #include "lib/stringinfo.h"
 #include "nodes/bitmapset.h"
 #include "nodes/lockoptions.h"
+#include "nodes/parsenodes.h"
 #include "nodes/primnodes.h"
 
 
@@ -42,7 +43,7 @@ typedef struct PlannedStmt
 {
 	NodeTag		type;
 
-	CmdType		commandType;	/* select|insert|update|delete|utility */
+	CmdType		commandType;	/* select|insert|update|delete|merge|utility */
 
 	uint64		queryId;		/* query identifier (copied from Query) */
 
@@ -216,13 +217,14 @@ typedef struct ProjectSet
 typedef struct ModifyTable
 {
 	Plan		plan;
-	CmdType		operation;		/* INSERT, UPDATE, or DELETE */
+	CmdType		operation;		/* INSERT, UPDATE, DELETE or MERGE */
 	bool		canSetTag;		/* do we set the command tag/es_processed? */
 	Index		nominalRelation;	/* Parent RT index for use of EXPLAIN */
 	/* RT indexes of non-leaf tables in a partition tree */
 	List	   *partitioned_rels;
 	bool		partColsUpdated;	/* some part key in hierarchy updated */
 	List	   *resultRelations;	/* integer list of RT indexes */
+	Index	    mergeTargetRelation;	/* RT index of the merge target */
 	int			resultRelIndex; /* index of first resultRel in plan's list */
 	int			rootResultRelIndex; /* index of the partitioned table root */
 	List	   *plans;			/* plan(s) producing source data */
@@ -238,6 +240,8 @@ typedef struct ModifyTable
 	Node	   *onConflictWhere;	/* WHERE for ON CONFLICT UPDATE */
 	Index		exclRelRTI;		/* RTI of the EXCLUDED pseudo relation */
 	List	   *exclRelTlist;	/* tlist of the EXCLUDED pseudo relation */
+	List	   *mergeSourceTargetList;
+	List	   *mergeActionList;	/* actions for MERGE */
 } ModifyTable;
 
 /* ----------------

src/include/nodes/relation.h

@@ -1670,7 +1670,7 @@ typedef struct LockRowsPath
 } LockRowsPath;
 
 /*
- * ModifyTablePath represents performing INSERT/UPDATE/DELETE modifications
+ * ModifyTablePath represents performing INSERT/UPDATE/DELETE/MERGE
  *
  * We represent most things that will be in the ModifyTable plan node
  * literally, except we have child Path(s) not Plan(s).  But analysis of the
@@ -1679,13 +1679,14 @@ typedef struct LockRowsPath
 typedef struct ModifyTablePath
 {
 	Path		path;
-	CmdType		operation;		/* INSERT, UPDATE, or DELETE */
+	CmdType		operation;		/* INSERT, UPDATE, DELETE or MERGE */
 	bool		canSetTag;		/* do we set the command tag/es_processed? */
 	Index		nominalRelation;	/* Parent RT index for use of EXPLAIN */
 	/* RT indexes of non-leaf tables in a partition tree */
 	List	   *partitioned_rels;
 	bool		partColsUpdated;	/* some part key in hierarchy updated */
 	List	   *resultRelations;	/* integer list of RT indexes */
+	Index	  	mergeTargetRelation;/* RT index of merge target relation */
 	List	   *subpaths;		/* Path(s) producing source data */
 	List	   *subroots;		/* per-target-table PlannerInfos */
 	List	   *withCheckOptionLists;	/* per-target-table WCO lists */
@@ -1693,6 +1694,8 @@ typedef struct ModifyTablePath
 	List	   *rowMarks;		/* PlanRowMarks (non-locking only) */
 	OnConflictExpr *onconflict; /* ON CONFLICT clause, or NULL */
 	int			epqParam;		/* ID of Param for EvalPlanQual re-eval */
+	List	   *mergeSourceTargetList;
+	List	   *mergeActionList;	/* actions for MERGE */
 } ModifyTablePath;
 
 /*