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

1 files changed, 8 insertions, 10 deletions

diff --git a/src/backend/parser/analyze.c b/src/backend/parser/analyze.c
index 606021bc94f..0c66ea1dfce 100644
--- a/src/backend/parser/analyze.c
+++ b/src/backend/parser/analyze.c
@@ -38,7 +38,6 @@
 #include "parser/parse_cte.h"
 #include "parser/parse_expr.h"
 #include "parser/parse_func.h"
-#include "parser/parse_merge.h"
 #include "parser/parse_oper.h"
 #include "parser/parse_param.h"
 #include "parser/parse_relation.h"
@@ -54,6 +53,9 @@ post_parse_analyze_hook_type post_parse_analyze_hook = NULL;
 static Query *transformOptionalSelectInto(ParseState *pstate, Node *parseTree);
 static Query *transformDeleteStmt(ParseState *pstate, DeleteStmt *stmt);
 static Query *transformInsertStmt(ParseState *pstate, InsertStmt *stmt);
+static List *transformInsertRow(ParseState *pstate, List *exprlist,
+				   List *stmtcols, List *icolumns, List *attrnos,
+				   bool strip_indirection);
 static OnConflictExpr *transformOnConflictClause(ParseState *pstate,
 						  OnConflictClause *onConflictClause);
 static int	count_rowexpr_columns(ParseState *pstate, Node *expr);
@@ -66,6 +68,8 @@ static void determineRecursiveColTypes(ParseState *pstate,
 						   Node *larg, List *nrtargetlist);
 static Query *transformUpdateStmt(ParseState *pstate, UpdateStmt *stmt);
 static List *transformReturningList(ParseState *pstate, List *returningList);
+static List *transformUpdateTargetList(ParseState *pstate,
+						  List *targetList);
 static Query *transformDeclareCursorStmt(ParseState *pstate,
 						   DeclareCursorStmt *stmt);
 static Query *transformExplainStmt(ParseState *pstate,
@@ -263,7 +267,6 @@ transformStmt(ParseState *pstate, Node *parseTree)
 		case T_InsertStmt:
 		case T_UpdateStmt:
 		case T_DeleteStmt:
-		case T_MergeStmt:
 			(void) test_raw_expression_coverage(parseTree, NULL);
 			break;
 		default:
@@ -288,10 +291,6 @@ transformStmt(ParseState *pstate, Node *parseTree)
 			result = transformUpdateStmt(pstate, (UpdateStmt *) parseTree);
 			break;
 
-		case T_MergeStmt:
-			result = transformMergeStmt(pstate, (MergeStmt *) parseTree);
-			break;
-
 		case T_SelectStmt:
 			{
 				SelectStmt *n = (SelectStmt *) parseTree;
@@ -367,7 +366,6 @@ analyze_requires_snapshot(RawStmt *parseTree)
 		case T_InsertStmt:
 		case T_DeleteStmt:
 		case T_UpdateStmt:
-		case T_MergeStmt:
 		case T_SelectStmt:
 			result = true;
 			break;
@@ -898,7 +896,7 @@ transformInsertStmt(ParseState *pstate, InsertStmt *stmt)
  * attrnos: integer column numbers (must be same length as icolumns)
  * strip_indirection: if true, remove any field/array assignment nodes
  */
-List *
+static List *
 transformInsertRow(ParseState *pstate, List *exprlist,
 				   List *stmtcols, List *icolumns, List *attrnos,
 				   bool strip_indirection)
@@ -2262,9 +2260,9 @@ transformUpdateStmt(ParseState *pstate, UpdateStmt *stmt)
 
 /*
  * transformUpdateTargetList -
- *	handle SET clause in UPDATE/MERGE/INSERT ... ON CONFLICT UPDATE
+ *	handle SET clause in UPDATE/INSERT ... ON CONFLICT UPDATE
  */
-List *
+static List *
 transformUpdateTargetList(ParseState *pstate, List *origTlist)
 {
 	List	   *tlist = NIL;