Directly modify foreign tables.

postgres_fdw can now sent an UPDATE or DELETE statement directly to
the foreign server in simple cases, rather than sending a SELECT FOR
UPDATE statement and then updating or deleting rows one-by-one.

Etsuro Fujita, reviewed by Rushabh Lathia, Shigeru Hanada, Kyotaro
Horiguchi, Albe Laurenz, Thom Brown, and me.

5 files changed, 29 insertions, 0 deletions

diff --git a/src/include/foreign/fdwapi.h b/src/include/foreign/fdwapi.h
index 71643602823..096a9c4a96d 100644
--- a/src/include/foreign/fdwapi.h
+++ b/src/include/foreign/fdwapi.h
@@ -97,6 +97,18 @@ typedef void (*EndForeignModify_function) (EState *estate,
 
 typedef int (*IsForeignRelUpdatable_function) (Relation rel);
 
+typedef bool (*PlanDirectModify_function) (PlannerInfo *root,
+										   ModifyTable *plan,
+										   Index resultRelation,
+										   int subplan_index);
+
+typedef void (*BeginDirectModify_function) (ForeignScanState *node,
+											int eflags);
+
+typedef TupleTableSlot *(*IterateDirectModify_function) (ForeignScanState *node);
+
+typedef void (*EndDirectModify_function) (ForeignScanState *node);
+
 typedef RowMarkType (*GetForeignRowMarkType_function) (RangeTblEntry *rte,
 												LockClauseStrength strength);
 
@@ -114,6 +126,9 @@ typedef void (*ExplainForeignModify_function) (ModifyTableState *mtstate,
 														   int subplan_index,
 													struct ExplainState *es);
 
+typedef void (*ExplainDirectModify_function) (ForeignScanState *node,
+													struct ExplainState *es);
+
 typedef int (*AcquireSampleRowsFunc) (Relation relation, int elevel,
 											   HeapTuple *rows, int targrows,
 												  double *totalrows,
@@ -181,6 +196,10 @@ typedef struct FdwRoutine
 	ExecForeignDelete_function ExecForeignDelete;
 	EndForeignModify_function EndForeignModify;
 	IsForeignRelUpdatable_function IsForeignRelUpdatable;
+	PlanDirectModify_function PlanDirectModify;
+	BeginDirectModify_function BeginDirectModify;
+	IterateDirectModify_function IterateDirectModify;
+	EndDirectModify_function EndDirectModify;
 
 	/* Functions for SELECT FOR UPDATE/SHARE row locking */
 	GetForeignRowMarkType_function GetForeignRowMarkType;
@@ -190,6 +209,7 @@ typedef struct FdwRoutine
 	/* Support functions for EXPLAIN */
 	ExplainForeignScan_function ExplainForeignScan;
 	ExplainForeignModify_function ExplainForeignModify;
+	ExplainDirectModify_function ExplainDirectModify;
 
 	/* Support functions for ANALYZE */
 	AnalyzeForeignTable_function AnalyzeForeignTable;
diff --git a/src/include/nodes/execnodes.h b/src/include/nodes/execnodes.h
index d35ec810450..0113e5c663c 100644
--- a/src/include/nodes/execnodes.h
+++ b/src/include/nodes/execnodes.h
@@ -311,6 +311,7 @@ typedef struct JunkFilter
  *		TrigInstrument			optional runtime measurements for triggers
  *		FdwRoutine				FDW callback functions, if foreign table
  *		FdwState				available to save private state of FDW
+ *		usesFdwDirectModify		true when modifying foreign table directly
  *		WithCheckOptions		list of WithCheckOption's to be checked
  *		WithCheckOptionExprs	list of WithCheckOption expr states
  *		ConstraintExprs			array of constraint-checking expr states
@@ -334,6 +335,7 @@ typedef struct ResultRelInfo
 	Instrumentation *ri_TrigInstrument;
 	struct FdwRoutine *ri_FdwRoutine;
 	void	   *ri_FdwState;
+	bool		ri_usesFdwDirectModify;
 	List	   *ri_WithCheckOptions;
 	List	   *ri_WithCheckOptionExprs;
 	List	  **ri_ConstraintExprs;
diff --git a/src/include/nodes/pg_list.h b/src/include/nodes/pg_list.h
index 1cb95ee7385..77b50ff1c74 100644
--- a/src/include/nodes/pg_list.h
+++ b/src/include/nodes/pg_list.h
@@ -134,16 +134,19 @@ list_length(const List *l)
 #define list_make2(x1,x2)			lcons(x1, list_make1(x2))
 #define list_make3(x1,x2,x3)		lcons(x1, list_make2(x2, x3))
 #define list_make4(x1,x2,x3,x4)		lcons(x1, list_make3(x2, x3, x4))
+#define list_make5(x1,x2,x3,x4,x5)	lcons(x1, list_make4(x2, x3, x4, x5))
 
 #define list_make1_int(x1)			lcons_int(x1, NIL)
 #define list_make2_int(x1,x2)		lcons_int(x1, list_make1_int(x2))
 #define list_make3_int(x1,x2,x3)	lcons_int(x1, list_make2_int(x2, x3))
 #define list_make4_int(x1,x2,x3,x4) lcons_int(x1, list_make3_int(x2, x3, x4))
+#define list_make5_int(x1,x2,x3,x4,x5)	lcons_int(x1, list_make4_int(x2, x3, x4, x5))
 
 #define list_make1_oid(x1)			lcons_oid(x1, NIL)
 #define list_make2_oid(x1,x2)		lcons_oid(x1, list_make1_oid(x2))
 #define list_make3_oid(x1,x2,x3)	lcons_oid(x1, list_make2_oid(x2, x3))
 #define list_make4_oid(x1,x2,x3,x4) lcons_oid(x1, list_make3_oid(x2, x3, x4))
+#define list_make5_oid(x1,x2,x3,x4,x5)	lcons_oid(x1, list_make4_oid(x2, x3, x4, x5))
 
 /*
  * foreach -
diff --git a/src/include/nodes/plannodes.h b/src/include/nodes/plannodes.h
index 5961f2c9884..00b1d35d759 100644
--- a/src/include/nodes/plannodes.h
+++ b/src/include/nodes/plannodes.h
@@ -189,6 +189,7 @@ typedef struct ModifyTable
 	List	   *withCheckOptionLists;	/* per-target-table WCO lists */
 	List	   *returningLists; /* per-target-table RETURNING tlists */
 	List	   *fdwPrivLists;	/* per-target-table FDW private data lists */
+	Bitmapset  *fdwDirectModifyPlans;	/* indices of FDW DM plans */
 	List	   *rowMarks;		/* PlanRowMarks (non-locking only) */
 	int			epqParam;		/* ID of Param for EvalPlanQual re-eval */
 	OnConflictAction onConflictAction;	/* ON CONFLICT action */
@@ -531,6 +532,7 @@ typedef struct WorkTableScan
 typedef struct ForeignScan
 {
 	Scan		scan;
+	CmdType		operation;		/* SELECT/INSERT/UPDATE/DELETE */
 	Oid			fs_server;		/* OID of foreign server */
 	List	   *fdw_exprs;		/* expressions that FDW may evaluate */
 	List	   *fdw_private;	/* private data for FDW */
diff --git a/src/include/optimizer/plancat.h b/src/include/optimizer/plancat.h
index 52335fae15a..125274e4902 100644
--- a/src/include/optimizer/plancat.h
+++ b/src/include/optimizer/plancat.h
@@ -55,4 +55,6 @@ extern Selectivity join_selectivity(PlannerInfo *root,
 				 JoinType jointype,
 				 SpecialJoinInfo *sjinfo);
 
+extern bool has_row_triggers(PlannerInfo *root, Index rti, CmdType event);
+
 #endif   /* PLANCAT_H */