Fix issue #1399 EXISTS doesn't handle non-existent labels (#1400)

regress/expected/cypher_match.out

@@ -2829,6 +2829,167 @@ SELECT * FROM cypher('cypher_match', $$ MATCH p1=(n {name:'Dave'})-[]->() MATCH
  true
 (1 row)
 
+--
+-- Issue 1399 EXISTS leads to an error if a relation label does not exists as database table
+--
+SELECT create_graph('issue_1399');
+NOTICE:  graph "issue_1399" has been created
+ create_graph 
+--------------
+
+(1 row)
+
+-- this is an empty graph so these should return 0
+SELECT * FROM cypher('issue_1399', $$
+  MATCH (foo)
+  WHERE exists((foo)-[]->())
+  RETURN foo
+$$) as (c agtype);
+ c 
+---
+(0 rows)
+
+SELECT * FROM cypher('issue_1399', $$
+  MATCH (foo)
+  WHERE NOT exists((foo)-[]->())
+  RETURN foo
+$$) as (c agtype);
+ c 
+---
+(0 rows)
+
+SELECT * FROM cypher('issue_1399', $$
+  MATCH (foo)
+  WHERE exists((foo)-[:BAR]->())
+  RETURN foo
+$$) as (c agtype);
+ c 
+---
+(0 rows)
+
+SELECT * FROM cypher('issue_1399', $$
+  MATCH (foo)
+  WHERE NOT exists((foo)-[:BAR]->())
+  RETURN foo
+$$) as (c agtype);
+ c 
+---
+(0 rows)
+
+-- this is an empty graph so these should return false
+SELECT * FROM cypher('issue_1399', $$
+  MATCH (foo)
+  WHERE exists((foo)-[]->())
+  RETURN count(foo) > 0
+$$) as (c agtype);
+   c   
+-------
+ false
+(1 row)
+
+SELECT * FROM cypher('issue_1399', $$
+  MATCH (foo)
+  WHERE NOT exists((foo)-[]->())
+  RETURN count(foo) > 0
+$$) as (c agtype);
+   c   
+-------
+ false
+(1 row)
+
+SELECT * FROM cypher('issue_1399', $$
+  MATCH (foo)
+  WHERE exists((foo)-[:BAR]->())
+  RETURN count(foo) > 0
+$$) as (c agtype);
+   c   
+-------
+ false
+(1 row)
+
+SELECT * FROM cypher('issue_1399', $$
+  MATCH (foo)
+  WHERE NOT exists((foo)-[:BAR]->())
+  RETURN count(foo) > 0
+$$) as (c agtype);
+   c   
+-------
+ false
+(1 row)
+
+-- create 1 path
+SELECT * FROM cypher('issue_1399', $$
+  CREATE (foo)-[:BAR]->() RETURN foo
+$$) as (c agtype);
+                               c                                
+----------------------------------------------------------------
+ {"id": 281474976710657, "label": "", "properties": {}}::vertex
+(1 row)
+
+-- these should each return 1 row as it is a directed edge and
+-- only one vertex can match.
+SELECT * FROM cypher('issue_1399', $$
+  MATCH (foo)
+  WHERE exists((foo)-[]->())
+  RETURN foo
+$$) as (c agtype);
+                               c                                
+----------------------------------------------------------------
+ {"id": 281474976710657, "label": "", "properties": {}}::vertex
+(1 row)
+
+SELECT * FROM cypher('issue_1399', $$
+  MATCH (foo)
+  WHERE NOT exists((foo)-[]->())
+  RETURN foo
+$$) as (c agtype);
+                               c                                
+----------------------------------------------------------------
+ {"id": 281474976710658, "label": "", "properties": {}}::vertex
+(1 row)
+
+SELECT * FROM cypher('issue_1399', $$
+  MATCH (foo)
+  WHERE exists((foo)-[:BAR]->())
+  RETURN foo
+$$) as (c agtype);
+                               c                                
+----------------------------------------------------------------
+ {"id": 281474976710657, "label": "", "properties": {}}::vertex
+(1 row)
+
+SELECT * FROM cypher('issue_1399', $$
+  MATCH (foo)
+  WHERE NOT exists((foo)-[:BAR]->())
+  RETURN foo
+$$) as (c agtype);
+                               c                                
+----------------------------------------------------------------
+ {"id": 281474976710658, "label": "", "properties": {}}::vertex
+(1 row)
+
+-- this should return 0 rows as it can't exist - that path isn't in BAR2
+SELECT * FROM cypher('issue_1399', $$
+  MATCH (foo)
+  WHERE exists((foo)-[:BAR2]->())
+  RETURN foo
+$$) as (c agtype);
+ c 
+---
+(0 rows)
+
+-- this should return 2 rows as they all exist
+SELECT * FROM cypher('issue_1399', $$
+  MATCH (foo)
+  WHERE NOT exists((foo)-[:BAR2]->())
+  RETURN foo
+$$) as (c agtype);
+                               c                                
+----------------------------------------------------------------
+ {"id": 281474976710657, "label": "", "properties": {}}::vertex
+ {"id": 281474976710658, "label": "", "properties": {}}::vertex
+(2 rows)
+
 --
 -- Clean up
 --
@@ -2892,6 +3053,17 @@ NOTICE:  graph "issue_945" has been dropped
 
 (1 row)
 
+SELECT drop_graph('issue_1399', true);
+NOTICE:  drop cascades to 3 other objects
+DETAIL:  drop cascades to table issue_1399._ag_label_vertex
+drop cascades to table issue_1399._ag_label_edge
+drop cascades to table issue_1399."BAR"
+NOTICE:  graph "issue_1399" has been dropped
+ drop_graph 
+------------
+
+(1 row)
+
 --
 -- End
 --

regress/sql/cypher_match.sql

@@ -1178,13 +1178,99 @@ SELECT * FROM cypher('cypher_match', $$ MATCH p=()-[*]->() WHERE size(nodes(p))
 SELECT * FROM cypher('cypher_match', $$ MATCH (n {name:'Dave'}) MATCH p=()-[*]->() WHERE nodes(p)[0] = n RETURN length(p) $$) as (length agtype);
 SELECT * FROM cypher('cypher_match', $$ MATCH p1=(n {name:'Dave'})-[]->() MATCH p2=()-[*]->() WHERE p2=p1 RETURN p2=p1 $$) as (path agtype);
 
+--
+-- Issue 1399 EXISTS leads to an error if a relation label does not exists as database table
+--
+SELECT create_graph('issue_1399');
+-- this is an empty graph so these should return 0
+SELECT * FROM cypher('issue_1399', $$
+  MATCH (foo)
+  WHERE exists((foo)-[]->())
+  RETURN foo
+$$) as (c agtype);
+SELECT * FROM cypher('issue_1399', $$
+  MATCH (foo)
+  WHERE NOT exists((foo)-[]->())
+  RETURN foo
+$$) as (c agtype);
+SELECT * FROM cypher('issue_1399', $$
+  MATCH (foo)
+  WHERE exists((foo)-[:BAR]->())
+  RETURN foo
+$$) as (c agtype);
+SELECT * FROM cypher('issue_1399', $$
+  MATCH (foo)
+  WHERE NOT exists((foo)-[:BAR]->())
+  RETURN foo
+$$) as (c agtype);
+-- this is an empty graph so these should return false
+SELECT * FROM cypher('issue_1399', $$
+  MATCH (foo)
+  WHERE exists((foo)-[]->())
+  RETURN count(foo) > 0
+$$) as (c agtype);
+SELECT * FROM cypher('issue_1399', $$
+  MATCH (foo)
+  WHERE NOT exists((foo)-[]->())
+  RETURN count(foo) > 0
+$$) as (c agtype);
+SELECT * FROM cypher('issue_1399', $$
+  MATCH (foo)
+  WHERE exists((foo)-[:BAR]->())
+  RETURN count(foo) > 0
+$$) as (c agtype);
+SELECT * FROM cypher('issue_1399', $$
+  MATCH (foo)
+  WHERE NOT exists((foo)-[:BAR]->())
+  RETURN count(foo) > 0
+$$) as (c agtype);
+-- create 1 path
+SELECT * FROM cypher('issue_1399', $$
+  CREATE (foo)-[:BAR]->() RETURN foo
+$$) as (c agtype);
+-- these should each return 1 row as it is a directed edge and
+-- only one vertex can match.
+SELECT * FROM cypher('issue_1399', $$
+  MATCH (foo)
+  WHERE exists((foo)-[]->())
+  RETURN foo
+$$) as (c agtype);
+SELECT * FROM cypher('issue_1399', $$
+  MATCH (foo)
+  WHERE NOT exists((foo)-[]->())
+  RETURN foo
+$$) as (c agtype);
+SELECT * FROM cypher('issue_1399', $$
+  MATCH (foo)
+  WHERE exists((foo)-[:BAR]->())
+  RETURN foo
+$$) as (c agtype);
+SELECT * FROM cypher('issue_1399', $$
+  MATCH (foo)
+  WHERE NOT exists((foo)-[:BAR]->())
+  RETURN foo
+$$) as (c agtype);
+-- this should return 0 rows as it can't exist - that path isn't in BAR2
+SELECT * FROM cypher('issue_1399', $$
+  MATCH (foo)
+  WHERE exists((foo)-[:BAR2]->())
+  RETURN foo
+$$) as (c agtype);
+-- this should return 2 rows as they all exist
+SELECT * FROM cypher('issue_1399', $$
+  MATCH (foo)
+  WHERE NOT exists((foo)-[:BAR2]->())
+  RETURN foo
+$$) as (c agtype);
+
 --
 -- Clean up
 --
 SELECT drop_graph('cypher_match', true);
 SELECT drop_graph('test_retrieve_var', true);
 SELECT drop_graph('test_enable_containment', true);
 SELECT drop_graph('issue_945', true);
+SELECT drop_graph('issue_1399', true);
 
 --
 -- End

src/backend/parser/cypher_transform_entity.c

@@ -114,33 +114,40 @@ transform_entity *find_variable(cypher_parsestate *cpstate, char *name)
 {
     ListCell *lc;
 
-    foreach (lc, cpstate->entities)
+    /* while we have cypher_parsestates to check */
+    while (cpstate)
     {
-        transform_entity *entity = lfirst(lc);
-        char *entity_name;
-
-        if (entity->type == ENT_VERTEX)
-        {
-            entity_name = entity->entity.node->name;
-        }
-        else if (entity->type == ENT_EDGE || entity->type == ENT_VLE_EDGE)
-        {
-            entity_name = entity->entity.rel->name;
-        }
-        else if (entity->type == ENT_PATH)
+        foreach (lc, cpstate->entities)
         {
-            entity_name = entity->entity.path->var_name;
-        }
-        else
-        {
-            ereport(ERROR, (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
-                            errmsg("unknown entity type")));
-        }
+            transform_entity *entity = lfirst(lc);
+            char *entity_name = NULL;
 
-        if (entity_name != NULL && !strcmp(name, entity_name))
-        {
-            return entity;
+            if (entity->type == ENT_VERTEX)
+            {
+                entity_name = entity->entity.node->name;
+            }
+            else if (entity->type == ENT_EDGE || entity->type == ENT_VLE_EDGE)
+            {
+                entity_name = entity->entity.rel->name;
+            }
+            else if (entity->type == ENT_PATH)
+            {
+                entity_name = entity->entity.path->var_name;
+            }
+            else
+            {
+                ereport(ERROR, (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+                                errmsg("unknown entity type")));
+            }
+
+            if (entity_name != NULL && !strcmp(name, entity_name))
+            {
+                return entity;
+            }
         }
+
+        /* go up to the next parent parse state */
+        cpstate = (cypher_parsestate*)cpstate->pstate.parentParseState;
     }
 
     return NULL;