Revert MERGE patch

This reverts commits d204ef63776b8a00ca220adec23979091564e465,
83454e3c2b28141c0db01c7d2027e01040df5249 and a few more commits thereafter
(complete list at the end) related to MERGE feature.

While the feature was fully functional, with sufficient test coverage and
necessary documentation, it was felt that some parts of the executor and
parse-analyzer can use a different design and it wasn't possible to do that in
the available time. So it was decided to revert the patch for PG11 and retry
again in the future.

Thanks again to all reviewers and bug reporters.

List of commits reverted, in reverse chronological order:

 f1464c5380 Improve parse representation for MERGE
 ddb4158579 MERGE syntax diagram correction
 530e69e59b Allow cpluspluscheck to pass by renaming variable
 01b88b4df5 MERGE minor errata
 3af7b2b0d4 MERGE fix variable warning in non-assert builds
 a5d86181ec MERGE INSERT allows only one VALUES clause
 4b2d44031f MERGE post-commit review
 4923550c20 Tab completion for MERGE
 aa3faa3c7a WITH support in MERGE
 83454e3c2b New files for MERGE
 d204ef6377 MERGE SQL Command following SQL:2016

Author: Pavan Deolasee
Reviewed-by: Michael Paquier

5 files changed, 2 insertions, 61 deletions

diff --git a/src/include/executor/execMerge.h b/src/include/executor/execMerge.h
deleted file mode 100644
index 5ea8c4e50a8..00000000000
--- a/src/include/executor/execMerge.h
+++ /dev/null
@@ -1,31 +0,0 @@
-/*-------------------------------------------------------------------------
- *
- * execMerge.h
- *
- *
- * Portions Copyright (c) 1996-2018, PostgreSQL Global Development Group
- * Portions Copyright (c) 1994, Regents of the University of California
- *
- * src/include/executor/execMerge.h
- *
- *-------------------------------------------------------------------------
- */
-#ifndef EXECMERGE_H
-#define EXECMERGE_H
-
-#include "nodes/execnodes.h"
-
-/* flags for mt_merge_subcommands */
-#define MERGE_INSERT	0x01
-#define MERGE_UPDATE	0x02
-#define MERGE_DELETE	0x04
-
-extern void ExecMerge(ModifyTableState *mtstate, EState *estate,
-					  TupleTableSlot *slot, JunkFilter *junkfilter,
-					  ResultRelInfo *resultRelInfo);
-
-extern void ExecInitMerge(ModifyTableState *mtstate,
-						  EState *estate,
-						  ResultRelInfo *resultRelInfo);
-
-#endif							/* NODEMERGE_H */
diff --git a/src/include/executor/execPartition.h b/src/include/executor/execPartition.h
index b2daf24c41d..0c36c8be30c 100644
--- a/src/include/executor/execPartition.h
+++ b/src/include/executor/execPartition.h
@@ -186,7 +186,6 @@ extern int ExecFindPartition(ResultRelInfo *resultRelInfo,
 				  PartitionDispatch *pd,
 				  TupleTableSlot *slot,
 				  EState *estate);
-extern int ExecFindPartitionByOid(PartitionTupleRouting *proute, Oid partoid);
 extern ResultRelInfo *ExecInitPartitionInfo(ModifyTableState *mtstate,
 					ResultRelInfo *resultRelInfo,
 					PartitionTupleRouting *proute,
diff --git a/src/include/executor/instrument.h b/src/include/executor/instrument.h
index 1bc7a88dbd6..6e3c71759b8 100644
--- a/src/include/executor/instrument.h
+++ b/src/include/executor/instrument.h
@@ -59,11 +59,8 @@ typedef struct Instrumentation
 	double		ntuples;		/* Total tuples produced */
 	double		ntuples2;		/* Secondary node-specific tuple counter */
 	double		nloops;			/* # of run cycles for this node */
-	double		nfiltered1;		/* # tuples removed by scanqual or joinqual OR
-								 * # tuples inserted by MERGE */
-	double		nfiltered2;		/* # tuples removed by "other" quals OR
-								 * # tuples updated by MERGE */
-	double		nfiltered3;		/* # tuples deleted by MERGE */
+	double      nfiltered1;     /* # tuples removed by scanqual or joinqual */
+	double      nfiltered2;     /* # tuples removed by "other" quals */
 	BufferUsage bufusage;		/* Total buffer usage */
 } Instrumentation;
 
diff --git a/src/include/executor/nodeModifyTable.h b/src/include/executor/nodeModifyTable.h
index 7e9ab3cb6b4..0d7e579e1cb 100644
--- a/src/include/executor/nodeModifyTable.h
+++ b/src/include/executor/nodeModifyTable.h
@@ -18,28 +18,5 @@
 extern ModifyTableState *ExecInitModifyTable(ModifyTable *node, EState *estate, int eflags);
 extern void ExecEndModifyTable(ModifyTableState *node);
 extern void ExecReScanModifyTable(ModifyTableState *node);
-extern TupleTableSlot *ExecPrepareTupleRouting(ModifyTableState *mtstate,
-						EState *estate,
-						struct PartitionTupleRouting *proute,
-						ResultRelInfo *targetRelInfo,
-						TupleTableSlot *slot);
-extern TupleTableSlot *ExecDelete(ModifyTableState *mtstate,
-		   ItemPointer tupleid, HeapTuple oldtuple, TupleTableSlot *planSlot,
-		   EPQState *epqstate, EState *estate, bool *tupleDeleted,
-		   bool processReturning, HeapUpdateFailureData *hufdp,
-		   MergeActionState *actionState, bool canSetTag,
-		   bool changingPart);
-extern TupleTableSlot *ExecUpdate(ModifyTableState *mtstate,
-		   ItemPointer tupleid, HeapTuple oldtuple, TupleTableSlot *slot,
-		   TupleTableSlot *planSlot, EPQState *epqstate, EState *estate,
-		   bool *tuple_updated, HeapUpdateFailureData *hufdp,
-		   MergeActionState *actionState, bool canSetTag);
-extern TupleTableSlot *ExecInsert(ModifyTableState *mtstate,
-		   TupleTableSlot *slot,
-		   TupleTableSlot *planSlot,
-		   EState *estate,
-		   MergeActionState *actionState,
-		   bool canSetTag);
-extern void ExecCheckPlanOutput(Relation resultRel, List *targetList);
 
 #endif							/* NODEMODIFYTABLE_H */
diff --git a/src/include/executor/spi.h b/src/include/executor/spi.h
index 78410b9f772..e5bdaecc4e3 100644
--- a/src/include/executor/spi.h
+++ b/src/include/executor/spi.h
@@ -64,7 +64,6 @@ typedef struct _SPI_plan *SPIPlanPtr;
 #define SPI_OK_REL_REGISTER		15
 #define SPI_OK_REL_UNREGISTER	16
 #define SPI_OK_TD_REGISTER		17
-#define SPI_OK_MERGE			18
 
 #define SPI_OPT_NONATOMIC		(1 << 0)