jihot2000 commented on issue #220:
URL: https://github.com/apache/incubator-age/issues/220#issuecomment-1135396842
I split the sql file into two files.
First, the ```use_loop.sql```
```
CREATE SCHEMA test_vle;
SET search_path = test_vle, ag_catalog, "$user";
SELECT create_graph('mygraph');
SELECT create_vlabel('mygraph', 'head');
SELECT create_vlabel('mygraph', 'tail');
SELECT create_vlabel('mygraph', 'node');
SELECT create_elabel('mygraph', 'next');
CREATE OR REPLACE FUNCTION create_list(list_name text)
RETURNS void
LANGUAGE 'plpgsql'
AS $$
DECLARE
ag_param agtype;
BEGIN
ag_param = FORMAT('{"list_name": "%s"}', $1)::agtype;
PERFORM * FROM cypher('mygraph', $CYPHER$
MERGE (:head {name: $list_name})-[:next]->(:tail {name: $list_name})
$CYPHER$, ag_param) AS (a agtype);
END $$;
CREATE OR REPLACE FUNCTION prepend_node(list_name text, node_content text)
RETURNS void
LANGUAGE 'plpgsql'
AS $$
DECLARE
ag_param agtype;
BEGIN
ag_param = FORMAT('{"list_name": "%s", "node_content": "%s"}', $1,
$2)::agtype;
PERFORM * FROM cypher('mygraph', $CYPHER$
MATCH (h:head {name: $list_name})-[e:next]->(v)
DELETE e
CREATE (h)-[:next]->(:node {content: $node_content})-[:next]->(v)
$CYPHER$, ag_param) AS (a agtype);
END $$;
CREATE OR REPLACE FUNCTION show_list_use_loop(list_name text)
RETURNS TABLE(node agtype)
LANGUAGE 'plpgsql'
AS $$
DECLARE
node_id bigint;
ag_param agtype;
BEGIN
ag_param = FORMAT('{"list_name": "%s"}', $1)::agtype;
SELECT g.id INTO node_id FROM cypher('mygraph', $CYPHER$
MATCH (h:head {name: $list_name})
RETURN id(h)
$CYPHER$, ag_param) AS g(id bigint);
IF node_id IS NULL THEN
RETURN;
END IF;
LOOP
ag_param = FORMAT('{"node_id": %s}', node_id)::agtype;
SELECT g.id, g.node INTO node_id, node FROM cypher('mygraph',
$CYPHER$
MATCH (p)-[e:next]->(v:node)
WHERE id(p) = $node_id
RETURN id(v), v
$CYPHER$, ag_param) AS g(id bigint, node agtype);
EXIT WHEN node_id IS NULL;
RETURN NEXT;
END LOOP;
END $$;
-- create a list
SELECT create_list('list01');
-- prepend a node 'a'
SELECT prepend_node('list01', 'a');
SELECT * FROM show_list_use_loop('list01');
-- prepend a node 'b'
SELECT prepend_node('list01', 'b');
SELECT * FROM show_list_use_loop('list01');
SELECT drop_graph('mygraph', true);
```
Its output is right:
```
CREATE SCHEMA
SET
psql:06.sql:5: NOTICE: graph "mygraph" has been created
create_graph
--------------
(1 row)
psql:06.sql:6: NOTICE: VLabel "head" has been created
create_vlabel
---------------
(1 row)
psql:06.sql:7: NOTICE: VLabel "tail" has been created
create_vlabel
---------------
(1 row)
psql:06.sql:8: NOTICE: VLabel "node" has been created
create_vlabel
---------------
(1 row)
psql:06.sql:9: NOTICE: ELabel "next" has been created
create_elabel
---------------
(1 row)
CREATE FUNCTION
CREATE FUNCTION
CREATE FUNCTION
create_list
-------------
(1 row)
prepend_node
--------------
(1 row)
node
-----------------------------------------------------------------------------------
{"id": 1407374883553281, "label": "node", "properties": {"content":
"a"}}::vertex
(1 row)
prepend_node
--------------
(1 row)
node
-----------------------------------------------------------------------------------
{"id": 1407374883553282, "label": "node", "properties": {"content":
"b"}}::vertex
{"id": 1407374883553281, "label": "node", "properties": {"content":
"a"}}::vertex
(2 rows)
psql:06.sql:80: NOTICE: drop cascades to 6 other objects
DETAIL: drop cascades to table mygraph._ag_label_vertex
drop cascades to table mygraph._ag_label_edge
drop cascades to table mygraph.head
drop cascades to table mygraph.tail
drop cascades to table mygraph.node
drop cascades to table mygraph.next
psql:06.sql:80: NOTICE: graph "mygraph" has been dropped
drop_graph
------------
(1 row)
psql:06.sql:82: NOTICE: drop cascades to 3 other objects
DETAIL: drop cascades to function create_list(text)
drop cascades to function prepend_node(text,text)
drop cascades to function show_list_use_loop(text)
DROP SCHEMA
```
Second, the 'use_vle.sql':
```
CREATE SCHEMA test_vle;
SET search_path = test_vle, ag_catalog, "$user";
SELECT create_graph('mygraph');
SELECT create_vlabel('mygraph', 'head');
SELECT create_vlabel('mygraph', 'tail');
SELECT create_vlabel('mygraph', 'node');
SELECT create_elabel('mygraph', 'next');
CREATE OR REPLACE FUNCTION create_list(list_name text)
RETURNS void
LANGUAGE 'plpgsql'
AS $$
DECLARE
ag_param agtype;
BEGIN
ag_param = FORMAT('{"list_name": "%s"}', $1)::agtype;
PERFORM * FROM cypher('mygraph', $CYPHER$
MERGE (:head {name: $list_name})-[:next]->(:tail {name: $list_name})
$CYPHER$, ag_param) AS (a agtype);
END $$;
CREATE OR REPLACE FUNCTION prepend_node(list_name text, node_content text)
RETURNS void
LANGUAGE 'plpgsql'
AS $$
DECLARE
ag_param agtype;
BEGIN
ag_param = FORMAT('{"list_name": "%s", "node_content": "%s"}', $1,
$2)::agtype;
PERFORM * FROM cypher('mygraph', $CYPHER$
MATCH (h:head {name: $list_name})-[e:next]->(v)
DELETE e
CREATE (h)-[:next]->(:node {content: $node_content})-[:next]->(v)
$CYPHER$, ag_param) AS (a agtype);
END $$;
CREATE OR REPLACE FUNCTION show_list_use_vle(list_name text)
RETURNS TABLE(node agtype)
LANGUAGE 'plpgsql'
AS $$
DECLARE
ag_param agtype;
BEGIN
ag_param = FORMAT('{"list_name": "%s"}', $1)::agtype;
RETURN QUERY
SELECT * FROM cypher('mygraph', $CYPHER$
MATCH (h:head {name: $list_name})-[e:next*]->(v:node)
RETURN v
$CYPHER$, ag_param) AS (node agtype);
END $$;
-- create a list
SELECT create_list('list01');
-- prepend a node 'a'
SELECT prepend_node('list01', 'a');
SELECT * FROM show_list_use_vle('list01');
-- prepend a node 'b'
SELECT prepend_node('list01', 'b');
SELECT * FROM show_list_use_vle('list01');
SELECT drop_graph('mygraph', true);
DROP SCHEMA test_vle CASCADE;
```
Its output is wrong:
```
CREATE SCHEMA
SET
psql:07.sql:5: NOTICE: graph "mygraph" has been created
create_graph
--------------
(1 row)
psql:07.sql:6: NOTICE: VLabel "head" has been created
create_vlabel
---------------
(1 row)
psql:07.sql:7: NOTICE: VLabel "tail" has been created
create_vlabel
---------------
(1 row)
psql:07.sql:8: NOTICE: VLabel "node" has been created
create_vlabel
---------------
(1 row)
psql:07.sql:9: NOTICE: ELabel "next" has been created
create_elabel
---------------
(1 row)
CREATE FUNCTION
CREATE FUNCTION
CREATE FUNCTION
create_list
-------------
(1 row)
prepend_node
--------------
(1 row)
node
-----------------------------------------------------------------------------------
{"id": 1407374883553281, "label": "node", "properties": {"content":
"a"}}::vertex
(1 row)
prepend_node
--------------
(1 row)
node
-----------------------------------------------------------------------------------
{"id": 1407374883553281, "label": "node", "properties": {"content":
"a"}}::vertex
(1 row)
psql:07.sql:65: NOTICE: drop cascades to 6 other objects
DETAIL: drop cascades to table mygraph._ag_label_vertex
drop cascades to table mygraph._ag_label_edge
drop cascades to table mygraph.head
drop cascades to table mygraph.tail
drop cascades to table mygraph.node
drop cascades to table mygraph.next
psql:07.sql:65: NOTICE: graph "mygraph" has been dropped
drop_graph
------------
(1 row)
psql:07.sql:67: NOTICE: drop cascades to 3 other objects
DETAIL: drop cascades to function create_list(text)
drop cascades to function prepend_node(text,text)
drop cascades to function show_list_use_vle(text)
DROP SCHEMA
```
The question is the output after prepend node 'b' of ```use_loop.sql``` is
right. Both node 'b' and node 'a' are printed. But the output after prepend
node 'b' of ```use_vle.sql``` is wrong. It only printed node 'a'.
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