fix RuntimeAppend + dropped columns

Author: funbringer

expected/pathman_runtime_nodes.out

@@ -403,6 +403,37 @@ where parent = 'test.runtime_test_4'::regclass and coalesce(range_min::int, 1) <
  t
 (1 row)
 
+/* RuntimeAppend (check that dropped columns don't break tlists) */
+create table test.dropped_cols(val int4 not null);
+select pathman.create_hash_partitions('test.dropped_cols', 'val', 4);
+ create_hash_partitions 
+------------------------
+                      4
+(1 row)
+
+insert into test.dropped_cols select generate_series(1, 100);
+alter table test.dropped_cols add column new_col text;	/* add column */
+alter table test.dropped_cols drop column new_col;		/* drop column! */
+explain (costs off) select * from generate_series(1, 10) f(id), lateral (select count(1) FILTER (WHERE true) from test.dropped_cols where val = f.id) c;
+                        QUERY PLAN                         
+-----------------------------------------------------------
+ Nested Loop
+   ->  Function Scan on generate_series f
+   ->  Aggregate
+         ->  Custom Scan (RuntimeAppend)
+               Prune by: (dropped_cols.val = f.id)
+               ->  Seq Scan on dropped_cols_0 dropped_cols
+                     Filter: (val = f.id)
+               ->  Seq Scan on dropped_cols_1 dropped_cols
+                     Filter: (val = f.id)
+               ->  Seq Scan on dropped_cols_2 dropped_cols
+                     Filter: (val = f.id)
+               ->  Seq Scan on dropped_cols_3 dropped_cols
+                     Filter: (val = f.id)
+(13 rows)
+
+drop table test.dropped_cols cascade;
+NOTICE:  drop cascades to 4 other objects
 set enable_hashjoin = off;
 set enable_mergejoin = off;
 select from test.runtime_test_4

sql/pathman_runtime_nodes.sql

@@ -312,6 +312,15 @@ join (select * from test.run_values limit 4) as t2 on t1.id = t2.val;
 select count(*) = 0 from pathman.pathman_partition_list
 where parent = 'test.runtime_test_4'::regclass and coalesce(range_min::int, 1) < 0;
 
+/* RuntimeAppend (check that dropped columns don't break tlists) */
+create table test.dropped_cols(val int4 not null);
+select pathman.create_hash_partitions('test.dropped_cols', 'val', 4);
+insert into test.dropped_cols select generate_series(1, 100);
+alter table test.dropped_cols add column new_col text;	/* add column */
+alter table test.dropped_cols drop column new_col;		/* drop column! */
+explain (costs off) select * from generate_series(1, 10) f(id), lateral (select count(1) FILTER (WHERE true) from test.dropped_cols where val = f.id) c;
+drop table test.dropped_cols cascade;
+
 set enable_hashjoin = off;
 set enable_mergejoin = off;
 

src/nodes_common.c

@@ -141,18 +141,41 @@ build_parent_tlist(List *tlist, AppendRelInfo *appinfo)
 
 	foreach (lc1, pulled_vars)
 	{
-		Var *tlist_var = (Var *) lfirst(lc1);
+		Var		   *tlist_var = (Var *) lfirst(lc1);
+		bool		found_column = false;
+		AttrNumber	attnum;
 
-		AttrNumber attnum = 0;
+		/* Skip system attributes */
+		if (tlist_var->varattno < InvalidAttrNumber)
+			continue;
+
+		attnum = 0;
 		foreach (lc2, appinfo->translated_vars)
 		{
 			Var *translated_var = (Var *) lfirst(lc2);
 
+			/* Don't forget to inc 'attunum'! */
 			attnum++;
 
+			/* Skip dropped columns */
+			if (!translated_var)
+				continue;
+
+			/* Find this column in list of parent table columns */
 			if (translated_var->varattno == tlist_var->varattno)
+			{
 				tlist_var->varattno = attnum;
+				found_column = true; /* successful mapping */
+			}
 		}
+
+		/* Raise ERROR if mapping failed */
+		if (!found_column)
+			elog(ERROR,
+				 "table \"%s\" has no attribute %d of partition \"%s\"",
+				 get_rel_name_or_relid(appinfo->parent_relid),
+				 tlist_var->varoattno,
+				 get_rel_name_or_relid(appinfo->child_relid));
 	}
 
 	ChangeVarNodes((Node *) temp_tlist,