Remove the new UPSERT command tag and use INSERT instead.

Previously, INSERT with ON CONFLICT DO UPDATE specified used a new
command tag -- UPSERT.  It was introduced out of concern that INSERT as
a command tag would be a misrepresentation for ON CONFLICT DO UPDATE, as
some affected rows may actually have been updated.

Alvaro Herrera noticed that the implementation of that new command tag
was incomplete; in subsequent discussion we concluded that having it
doesn't provide benefits that are in line with the compatibility breaks
it requires.

Catversion bump due to the removal of PlannedStmt->isUpsert.

Author: Peter Geoghegan
Discussion: 20150520215816.GI5885@postgresql.org

src/backend/nodes/copyfuncs.c

@@ -81,7 +81,6 @@ _copyPlannedStmt(const PlannedStmt *from)
 	COPY_SCALAR_FIELD(queryId);
 	COPY_SCALAR_FIELD(hasReturning);
 	COPY_SCALAR_FIELD(hasModifyingCTE);
-	COPY_SCALAR_FIELD(isUpsert);
 	COPY_SCALAR_FIELD(canSetTag);
 	COPY_SCALAR_FIELD(transientPlan);
 	COPY_NODE_FIELD(planTree);

src/backend/nodes/outfuncs.c

@@ -243,7 +243,6 @@ _outPlannedStmt(StringInfo str, const PlannedStmt *node)
 	WRITE_UINT_FIELD(queryId);
 	WRITE_BOOL_FIELD(hasReturning);
 	WRITE_BOOL_FIELD(hasModifyingCTE);
-	WRITE_BOOL_FIELD(isUpsert);
 	WRITE_BOOL_FIELD(canSetTag);
 	WRITE_BOOL_FIELD(transientPlan);
 	WRITE_NODE_FIELD(planTree);

src/backend/optimizer/plan/planner.c

@@ -261,8 +261,6 @@ standard_planner(Query *parse, int cursorOptions, ParamListInfo boundParams)
 	result->queryId = parse->queryId;
 	result->hasReturning = (parse->returningList != NIL);
 	result->hasModifyingCTE = parse->hasModifyingCTE;
-	result->isUpsert =
-		(parse->onConflict && parse->onConflict->action == ONCONFLICT_UPDATE);
 	result->canSetTag = parse->canSetTag;
 	result->transientPlan = glob->transientPlan;
 	result->planTree = top_plan;

src/backend/tcop/pquery.c

@@ -202,14 +202,8 @@ ProcessQuery(PlannedStmt *plan,
 					lastOid = queryDesc->estate->es_lastoid;
 				else
 					lastOid = InvalidOid;
-				if (plan->isUpsert)
-					snprintf(completionTag, COMPLETION_TAG_BUFSIZE,
-							 "UPSERT %u %u",
-							 lastOid, queryDesc->estate->es_processed);
-				else
-					snprintf(completionTag, COMPLETION_TAG_BUFSIZE,
-							 "INSERT %u %u",
-							 lastOid, queryDesc->estate->es_processed);
+				snprintf(completionTag, COMPLETION_TAG_BUFSIZE,
+				   "INSERT %u %u", lastOid, queryDesc->estate->es_processed);
 				break;
 			case CMD_UPDATE:
 				snprintf(completionTag, COMPLETION_TAG_BUFSIZE,
@@ -1362,10 +1356,7 @@ PortalRunMulti(Portal portal, bool isTopLevel,
 	 * 0" here because technically there is no query of the matching tag type,
 	 * and printing a non-zero count for a different query type seems wrong,
 	 * e.g.  an INSERT that does an UPDATE instead should not print "0 1" if
-	 * one row was updated (unless the ON CONFLICT DO UPDATE, or "UPSERT"
-	 * variant of INSERT was used to update the row, where it's logically a
-	 * direct effect of the top level command).  See QueryRewrite(), step 3,
-	 * for details.
+	 * one row was updated.  See QueryRewrite(), step 3, for details.
 	 */
 	if (completionTag && completionTag[0] == '\0')
 	{
@@ -1375,8 +1366,6 @@ PortalRunMulti(Portal portal, bool isTopLevel,
 			sprintf(completionTag, "SELECT 0 0");
 		else if (strcmp(completionTag, "INSERT") == 0)
 			strcpy(completionTag, "INSERT 0 0");
-		else if (strcmp(completionTag, "UPSERT") == 0)
-			strcpy(completionTag, "UPSERT 0 0");
 		else if (strcmp(completionTag, "UPDATE") == 0)
 			strcpy(completionTag, "UPDATE 0");
 		else if (strcmp(completionTag, "DELETE") == 0)

src/bin/psql/common.c

@@ -894,12 +894,9 @@ PrintQueryResults(PGresult *results)
 				success = StoreQueryTuple(results);
 			else
 				success = PrintQueryTuples(results);
-			/*
-			 * if it's INSERT/UPSERT/UPDATE/DELETE RETURNING, also print status
-			 */
+			/* if it's INSERT/UPDATE/DELETE RETURNING, also print status */
 			cmdstatus = PQcmdStatus(results);
 			if (strncmp(cmdstatus, "INSERT", 6) == 0 ||
-				strncmp(cmdstatus, "UPSERT", 6) == 0 ||
 				strncmp(cmdstatus, "UPDATE", 6) == 0 ||
 				strncmp(cmdstatus, "DELETE", 6) == 0)
 				PrintQueryStatus(results);

src/include/catalog/catversion.h

@@ -53,6 +53,6 @@
  */
 
 /*							yyyymmddN */
-#define CATALOG_VERSION_NO	201505191
+#define CATALOG_VERSION_NO	201505231
 
 #endif

src/include/nodes/plannodes.h

@@ -45,8 +45,6 @@ typedef struct PlannedStmt
 
 	bool		hasModifyingCTE;	/* has insert|update|delete in WITH? */
 
-	bool		isUpsert;		/* is it insert ... ON CONFLICT UPDATE? */
-
 	bool		canSetTag;		/* do I set the command result tag? */
 
 	bool		transientPlan;	/* redo plan when TransactionXmin changes? */