Ignore whole-rows in INSERT/CONFLICT with partitioned tables

We had an Assert() preventing whole-row expressions from being used in
the SET clause of INSERT ON CONFLICT, but it seems unnecessary, given
some tests, so remove it.  Add a new test to exercise the case.

Still at ExecInitPartitionInfo, we used map_partition_varattnos (which
constructs an attribute map, then calls map_variable_attnos) using
the same two relations many times in different expressions and with
different parameters.  Constructing the map over and over is a waste.
To avoid this repeated work, construct the map once, and use
map_variable_attnos() directly instead.

Author: Amit Langote, per comments by me (Álvaro)
Discussion: https://postgr.es/m/20180326142016.m4st5e34chrzrknk@alvherre.pgsql

src/backend/executor/execPartition.c

@@ -24,6 +24,7 @@
 #include "nodes/makefuncs.h"
 #include "partitioning/partbounds.h"
 #include "partitioning/partprune.h"
+#include "rewrite/rewriteManip.h"
 #include "utils/lsyscache.h"
 #include "utils/partcache.h"
 #include "utils/rel.h"
@@ -307,8 +308,12 @@ ExecInitPartitionInfo(ModifyTableState *mtstate,
 	ModifyTable *node = (ModifyTable *) mtstate->ps.plan;
 	Relation	rootrel = resultRelInfo->ri_RelationDesc,
 				partrel;
+	Relation	firstResultRel = mtstate->resultRelInfo[0].ri_RelationDesc;
 	ResultRelInfo *leaf_part_rri;
 	MemoryContext oldContext;
+	AttrNumber *part_attnos = NULL;
+	bool		found_whole_row;
+	bool		equalTupdescs;
 
 	/*
 	 * We locked all the partitions in ExecSetupPartitionTupleRouting
@@ -356,6 +361,10 @@ ExecInitPartitionInfo(ModifyTableState *mtstate,
 						(node != NULL &&
 						 node->onConflictAction != ONCONFLICT_NONE));
 
+	/* if tuple descs are identical, we don't need to map the attrs */
+	equalTupdescs = equalTupleDescs(RelationGetDescr(partrel),
+									RelationGetDescr(firstResultRel));
+
 	/*
 	 * Build WITH CHECK OPTION constraints for the partition.  Note that we
 	 * didn't build the withCheckOptionList for partitions within the planner,
@@ -369,7 +378,6 @@ ExecInitPartitionInfo(ModifyTableState *mtstate,
 		List	   *wcoExprs = NIL;
 		ListCell   *ll;
 		int			firstVarno = mtstate->resultRelInfo[0].ri_RangeTableIndex;
-		Relation	firstResultRel = mtstate->resultRelInfo[0].ri_RelationDesc;
 
 		/*
 		 * In the case of INSERT on a partitioned table, there is only one
@@ -397,8 +405,22 @@ ExecInitPartitionInfo(ModifyTableState *mtstate,
 		/*
 		 * Convert Vars in it to contain this partition's attribute numbers.
 		 */
-		wcoList = map_partition_varattnos(wcoList, firstVarno,
-										  partrel, firstResultRel, NULL);
+		if (!equalTupdescs)
+		{
+			part_attnos =
+				convert_tuples_by_name_map(RelationGetDescr(partrel),
+										   RelationGetDescr(firstResultRel),
+										   gettext_noop("could not convert row type"));
+			wcoList = (List *)
+				map_variable_attnos((Node *) wcoList,
+									firstVarno, 0,
+									part_attnos,
+									RelationGetDescr(firstResultRel)->natts,
+									RelationGetForm(partrel)->reltype,
+									&found_whole_row);
+			/* We ignore the value of found_whole_row. */
+		}
+
 		foreach(ll, wcoList)
 		{
 			WithCheckOption *wco = castNode(WithCheckOption, lfirst(ll));
@@ -425,7 +447,6 @@ ExecInitPartitionInfo(ModifyTableState *mtstate,
 		ExprContext *econtext;
 		List	   *returningList;
 		int			firstVarno = mtstate->resultRelInfo[0].ri_RangeTableIndex;
-		Relation	firstResultRel = mtstate->resultRelInfo[0].ri_RelationDesc;
 
 		/* See the comment above for WCO lists. */
 		Assert((node->operation == CMD_INSERT &&
@@ -443,12 +464,26 @@ ExecInitPartitionInfo(ModifyTableState *mtstate,
 		 */
 		returningList = linitial(node->returningLists);
 
-		/*
-		 * Convert Vars in it to contain this partition's attribute numbers.
-		 */
-		returningList = map_partition_varattnos(returningList, firstVarno,
-												partrel, firstResultRel,
-												NULL);
+		if (!equalTupdescs)
+		{
+			/*
+			 * Convert Vars in it to contain this partition's attribute numbers.
+			 */
+			if (part_attnos == NULL)
+				part_attnos =
+					convert_tuples_by_name_map(RelationGetDescr(partrel),
+											   RelationGetDescr(firstResultRel),
+											   gettext_noop("could not convert row type"));
+			returningList = (List *)
+				map_variable_attnos((Node *) returningList,
+									firstVarno, 0,
+									part_attnos,
+									RelationGetDescr(firstResultRel)->natts,
+									RelationGetForm(partrel)->reltype,
+									&found_whole_row);
+			/* We ignore the value of found_whole_row. */
+		}
+
 		leaf_part_rri->ri_returningList = returningList;
 
 		/*
@@ -473,7 +508,6 @@ ExecInitPartitionInfo(ModifyTableState *mtstate,
 	{
 		TupleConversionMap *map = proute->parent_child_tupconv_maps[partidx];
 		int			firstVarno = mtstate->resultRelInfo[0].ri_RangeTableIndex;
-		Relation	firstResultRel = mtstate->resultRelInfo[0].ri_RelationDesc;
 		TupleDesc	partrelDesc = RelationGetDescr(partrel);
 		ExprContext *econtext = mtstate->ps.ps_ExprContext;
 		ListCell   *lc;
@@ -549,17 +583,33 @@ ExecInitPartitionInfo(ModifyTableState *mtstate,
 				 * target relation (firstVarno).
 				 */
 				onconflset = (List *) copyObject((Node *) node->onConflictSet);
-				onconflset =
-					map_partition_varattnos(onconflset, INNER_VAR, partrel,
-											firstResultRel, &found_whole_row);
-				Assert(!found_whole_row);
-				onconflset =
-					map_partition_varattnos(onconflset, firstVarno, partrel,
-											firstResultRel, &found_whole_row);
-				Assert(!found_whole_row);
-
-				/* Finally, adjust this tlist to match the partition. */
-				onconflset = adjust_partition_tlist(onconflset, map);
+				if (!equalTupdescs)
+				{
+					if (part_attnos == NULL)
+						part_attnos =
+							convert_tuples_by_name_map(RelationGetDescr(partrel),
+													   RelationGetDescr(firstResultRel),
+													   gettext_noop("could not convert row type"));
+					onconflset = (List *)
+						map_variable_attnos((Node *) onconflset,
+											INNER_VAR, 0,
+											part_attnos,
+											RelationGetDescr(firstResultRel)->natts,
+											RelationGetForm(partrel)->reltype,
+											&found_whole_row);
+					/* We ignore the value of found_whole_row. */
+					onconflset = (List *)
+						map_variable_attnos((Node *) onconflset,
+											firstVarno, 0,
+											part_attnos,
+											RelationGetDescr(firstResultRel)->natts,
+											RelationGetForm(partrel)->reltype,
+											&found_whole_row);
+					/* We ignore the value of found_whole_row. */
+
+					/* Finally, adjust this tlist to match the partition. */
+					onconflset = adjust_partition_tlist(onconflset, map);
+				}
 
 				/*
 				 * Build UPDATE SET's projection info.  The user of this
@@ -587,14 +637,25 @@ ExecInitPartitionInfo(ModifyTableState *mtstate,
 					List	   *clause;
 
 					clause = copyObject((List *) node->onConflictWhere);
-					clause = map_partition_varattnos(clause, INNER_VAR,
-													 partrel, firstResultRel,
-													 &found_whole_row);
-					Assert(!found_whole_row);
-					clause = map_partition_varattnos(clause, firstVarno,
-													 partrel, firstResultRel,
-													 &found_whole_row);
-					Assert(!found_whole_row);
+					if (!equalTupdescs)
+					{
+						clause = (List *)
+							map_variable_attnos((Node *) clause,
+												INNER_VAR, 0,
+												part_attnos,
+												RelationGetDescr(firstResultRel)->natts,
+												RelationGetForm(partrel)->reltype,
+												&found_whole_row);
+						/* We ignore the value of found_whole_row. */
+						clause = (List *)
+							map_variable_attnos((Node *) clause,
+												firstVarno, 0,
+												part_attnos,
+												RelationGetDescr(firstResultRel)->natts,
+												RelationGetForm(partrel)->reltype,
+												&found_whole_row);
+						/* We ignore the value of found_whole_row. */
+					}
 					leaf_part_rri->ri_onConflict->oc_WhereClause =
 						ExecInitQual((List *) clause, &mtstate->ps);
 				}

src/test/regress/expected/insert_conflict.out

@@ -884,4 +884,20 @@ insert into parted_conflict values (40, 'forty');
 insert into parted_conflict_1 values (40, 'cuarenta')
   on conflict (a) do update set b = excluded.b;
 ERROR:  there is no unique or exclusion constraint matching the ON CONFLICT specification
+-- test whole-row Vars in ON CONFLICT expressions
+create unique index on parted_conflict (a, b);
+alter table parted_conflict add c int;
+truncate parted_conflict;
+insert into parted_conflict values (50, 'cincuenta', 1);
+insert into parted_conflict values (50, 'cincuenta', 2)
+  on conflict (a, b) do update set (a, b, c) = row(excluded.*)
+  where parted_conflict = (50, text 'cincuenta', 1) and
+        excluded = (50, text 'cincuenta', 2);
+-- should see (50, 'cincuenta', 2)
+select * from parted_conflict order by a;
+ a  |     b     | c 
+----+-----------+---
+ 50 | cincuenta | 2
+(1 row)
+
 drop table parted_conflict;

src/test/regress/sql/insert_conflict.sql

@@ -559,3 +559,21 @@ insert into parted_conflict values (40, 'forty');
 insert into parted_conflict_1 values (40, 'cuarenta')
   on conflict (a) do update set b = excluded.b;
 drop table parted_conflict;
+
+-- test whole-row Vars in ON CONFLICT expressions
+create table parted_conflict (a int, b text, c int) partition by range (a);
+create table parted_conflict_1 (drp text, c int, a int, b text);
+alter table parted_conflict_1 drop column drp;
+create unique index on parted_conflict (a, b);
+alter table parted_conflict attach partition parted_conflict_1 for values from (0) to (1000);
+truncate parted_conflict;
+insert into parted_conflict values (50, 'cincuenta', 1);
+insert into parted_conflict values (50, 'cincuenta', 2)
+  on conflict (a, b) do update set (a, b, c) = row(excluded.*)
+  where parted_conflict = (50, text 'cincuenta', 1) and
+        excluded = (50, text 'cincuenta', 2);
+
+-- should see (50, 'cincuenta', 2)
+select * from parted_conflict order by a;
+
+drop table parted_conflict;