bitnine-oss
AgensGraph Error with Complex Cypher Query
Environment
Agensgraph commit version: a706a3966f676cc04bd285af1d2c44e4e23736cf Operating System: Ubuntu22.04 Installation Method: source code compilation
Step to reproduce:
-
Create the graph database: log33.txt
-
Execute the following query:
MATCH (n0 :L2)-[r0 :T1]->(n1 :L2)-[r1 :T3]->(n2 :L4),(n3 :L1)-[r2 :T0]->(n4 :L0)<-[r3 :T1]-(n5)
UNWIND [ -1864444377 , ( n2 . k28 ) ] AS a0
OPTIONAL MATCH (n0)-[m0*1..2]->(n1)-[m1*1..1]->(n2),(n1)-[r4 :T0]->(n4)<-[r5 :T3]-(n6 :L2) WHERE length(m0)=1 AND length(m1)=1 AND (((r1.k59) CONTAINS 'nCztB6') AND ((r4.id) <> (r5.id))) WITH n0, n1, r0, n2, r1, n3, n4, r2, n5, r3, a0, r4, n6, r5
OPTIONAL MATCH (n3)-[]->(n4)<-[]-(n5)
WITH r4 , a0
OPTIONAL MATCH (n0 :L2)-[ *..3]->(n2),(n7)<-[r6 :T2]-(n0 :L2) WHERE ((r4.k39) OR (n0.k13))
OPTIONAL MATCH (n7)<-[m4*1..1]-(n0:L2) WHERE length(m4)=1 WITH r4, a0, n0, n2, n7, r6
RETURN a0
It results in the following error:
ERROR: could not open relation with OID 0
But when I execute a simple version as below:
MATCH (n0 :L2)-[r0 :T1]->(n1 :L2)-[r1 :T3]->(n2 :L4), (n3 :L1)-[r2 :T0]->(n4 :L0)<-[r3 :T1]-(n5)
UNWIND [-1864444377, (n2.k28)] AS a0
OPTIONAL MATCH (n0)-[]->(n1)-[]->(n2), (n1)-[r4 :T0]->(n4)<-[r5 :T3]-(n6 :L2) WHERE (((r1.k59) CONTAINS 'nCztB6') AND ((r4.id) <> (r5.id)))
OPTIONAL MATCH (n3)-[]->(n4)<-[]-(n5)
WITH r4, a0
OPTIONAL MATCH (n0 :L2)-[ *..3]->(n2), (n7)<-[r6 :T2]-(n0 :L2) WHERE ((r4.k39) OR (n0.k13))
OPTIONAL MATCH (n7)<-[]-(n0 :L2)
RETURN a0
It returns:
a0
-------------
-1864444377
1841232600
(2 rows)
Analysis
When both queries are tested in Neo4j (after replacing length() with size()), they execute without errors and return identical results:
a0
-------------
-1864444377
1841232600
(2 rows)
The detailed steps to reproduce the error are outlined below. I hope this helpful:
Step to reproduce
First we create a fresh database server
-
mkdir data4 -
./bin/initdb -D ./data4 -
./bin/ag_ctl start -D ./data4 -l log4 -o "-p 5436" -
./bin/agens -p 5436 postgres
Now we are in the database server, and execute the following cmd:
-
CREATE GRAPH agens -
SET graph_path = agens - Create the graph database use the log33.txt file.
- Execute the following query:
MATCH (n0 :L2)-[r0 :T1]->(n1 :L2)-[r1 :T3]->(n2 :L4),(n3 :L1)-[r2 :T0]->(n4 :L0)<-[r3 :T1]-(n5)
UNWIND [ -1864444377 , ( n2 . k28 ) ] AS a0
OPTIONAL MATCH (n0)-[m0*1..2]->(n1)-[m1*1..1]->(n2),(n1)-[r4 :T0]->(n4)<-[r5 :T3]-(n6 :L2) WHERE length(m0)=1 AND length(m1)=1 AND (((r1.k59) CONTAINS 'nCztB6') AND ((r4.id) <> (r5.id))) WITH n0, n1, r0, n2, r1, n3, n4, r2, n5, r3, a0, r4, n6, r5
OPTIONAL MATCH (n3)-[]->(n4)<-[]-(n5)
WITH r4 , a0
OPTIONAL MATCH (n0 :L2)-[ *..3]->(n2),(n7)<-[r6 :T2]-(n0 :L2) WHERE ((r4.k39) OR (n0.k13))
OPTIONAL MATCH (n7)<-[m4*1..1]-(n0:L2) WHERE length(m4)=1 WITH r4, a0, n0, n2, n7, r6
RETURN a0
-
It results in the following error:
ERROR: could not open relation with OID 0
The log in log4 file is:
2025-06-13 16:07:00.023 CST [625665] LOG: starting PostgreSQL 15beta2 (AgensGraph 2.13-devel) on x86_64-pc-linux-gnu, compiled by gcc (Ubuntu 11.4.0-1ubuntu1~22.04) 11.4.0, 64-bit
2025-06-13 16:07:00.023 CST [625665] LOG: listening on IPv4 address "127.0.0.1", port 5436
2025-06-13 16:07:00.035 CST [625665] LOG: listening on Unix socket "/tmp/.s.PGSQL.5436"
2025-06-13 16:07:00.049 CST [625670] LOG: database system was shut down at 2025-06-13 16:06:19 CST
2025-06-13 16:07:00.059 CST [625665] LOG: database system is ready to accept connections
2025-06-13 16:09:25.869 CST [625836] ERROR: could not open relation with OID 0
2025-06-13 16:09:25.869 CST [625836] STATEMENT: MATCH (n0 :L2)-[r0 :T1]->(n1 :L2)-[r1 :T3]->(n2 :L4),(n3 :L1)-[r2 :T0]->(n4 :L0)<-[r3 :T1]-(n5)
UNWIND [ -1864444377 , ( n2 . k28 ) ] AS a0
OPTIONAL MATCH (n0)-[m0*1..2]->(n1)-[m1*1..1]->(n2),(n1)-[r4 :T0]->(n4)<-[r5 :T3]-(n6 :L2) WHERE length(m0)=1 AND length(m1)=1 AND (((r1.k59) CONTAINS 'nCztB6') AND ((r4.id) <> (r5.id))) WITH n0, n1, r0, n2, r1, n3, n4, r2, n5, r3, a0, r4, n6, r5
OPTIONAL MATCH (n3)-[]->(n4)<-[]-(n5)
WITH r4 , a0
OPTIONAL MATCH (n0 :L2)-[ *..3]->(n2),(n7)<-[r6 :T2]-(n0 :L2) WHERE ((r4.k39) OR (n0.k13))
OPTIONAL MATCH (n7)<-[m4*1..1]-(n0:L2) WHERE length(m4)=1 WITH r4, a0, n0, n2, n7, r6
RETURN a0;
2025-06-13 16:12:00.148 CST [625668] LOG: checkpoint starting: time
2025-06-13 16:12:28.041 CST [625668] LOG: checkpoint complete: wrote 280 buffers (1.7%); 0 WAL file(s) added, 0 removed, 0 recycled; write=27.802 s, sync=0.068 s, total=27.893 s; sync files=143, longest=0.006 s, average=0.001 s; distance=959 kB, estimate=959 kB
Oh sorry, I was on the different commit. After the pulling, I was able to reproduce your error.
That's why I deleted my post to prevent confusion. But I ended up making you post twice. Sorry about that.
Anyway, I'll try to fix it.
