*** a/src/backend/executor/nodeModifyTable.c
--- b/src/backend/executor/nodeModifyTable.c
***************
*** 45,51 ****
  #include "foreign/fdwapi.h"
  #include "miscadmin.h"
  #include "nodes/nodeFuncs.h"
- #include "parser/parsetree.h"
  #include "storage/bufmgr.h"
  #include "storage/lmgr.h"
  #include "utils/builtins.h"
--- 45,50 ----
***************
*** 1767,1786 **** ExecInitModifyTable(ModifyTable *node, EState *estate, int eflags)
  
  	estate->es_result_relation_info = saved_resultRelInfo;
  
- 	/* The root table RT index is at the head of the partitioned_rels list */
- 	if (node->partitioned_rels)
- 	{
- 		Index		root_rti;
- 		Oid			root_oid;
- 
- 		root_rti = linitial_int(node->partitioned_rels);
- 		root_oid = getrelid(root_rti, estate->es_range_table);
- 		rel = heap_open(root_oid, NoLock);		/* locked by InitPlan */
- 	}
- 	else
- 		rel = mtstate->resultRelInfo->ri_RelationDesc;
- 
  	/* Build state for INSERT tuple routing */
  	if (operation == CMD_INSERT &&
  		rel->rd_rel->relkind == RELKIND_PARTITIONED_TABLE)
  	{
--- 1766,1773 ----
  
  	estate->es_result_relation_info = saved_resultRelInfo;
  
  	/* Build state for INSERT tuple routing */
+ 	rel = mtstate->resultRelInfo->ri_RelationDesc;
  	if (operation == CMD_INSERT &&
  		rel->rd_rel->relkind == RELKIND_PARTITIONED_TABLE)
  	{
***************
*** 1959,1968 **** ExecInitModifyTable(ModifyTable *node, EState *estate, int eflags)
  		mtstate->ps.ps_ExprContext = NULL;
  	}
  
- 	/* Close the root partitioned rel if we opened it above. */
- 	if (rel != mtstate->resultRelInfo->ri_RelationDesc)
- 		heap_close(rel, NoLock);
- 
  	/*
  	 * If needed, Initialize target list, projection and qual for ON CONFLICT
  	 * DO UPDATE.
--- 1946,1951 ----