Why Query_parallelism affects the result of a join between two UUID columns

Question

I'm running the following test on ignite 2.10.0

I have 2 tables created with a query_parallelism=1 and without affinity key. When I join the 2 following tables I have the result as expected.

0: jdbc:ignite:thin://localhost:10800> SELECT "id" AS "_A_id", "source_id" AS "_A_source_id" FROM PUBLIC."source_ml_blue";
+--------------------------------------+--------------------------------------+
|                _A_id                 |             _A_source_id             |
+--------------------------------------+--------------------------------------+
| 86c068cd-da89-11eb-a185-3da86c6c6bb3 | 86c068cc-da89-11eb-a185-3da86c6c6bb3 |
+--------------------------------------+--------------------------------------+
1 row selected (0.004 seconds)
0: jdbc:ignite:thin://localhost:10800> SELECT "id" AS "_B_id", "flx_src_ip_text" AS "_B_src_ip" FROM PUBLIC."source_nprobe_tcp_blue";
+--------------------------------------+-----------+
|                _B_id                 | _B_src_ip |
+--------------------------------------+-----------+
| 86c068cc-da89-11eb-a185-3da86c6c6bb3 | 1.1.1.1   |
+--------------------------------------+-----------+
1 row selected (0.003 seconds)
0: jdbc:ignite:thin://localhost:10800> SELECT _A."id" AS "_A_id", _A."source_id" AS "_A_source_id", _B."id"  AS "_B_id", _B."flx_src_ip_text" AS "_B_src_ip" FROM PUBLIC."source_ml_blue" AS "_A" INNER JOIN  PUBLIC."source_nprobe_tcp_blue" AS "_B" ON "_A"."source_id"="_B"."id";
+--------------------------------------+--------------------------------------+--------------------------------------+-----------+
|                _A_id                 |             _A_source_id             |                _B_id                 | _B_src_ip |
+--------------------------------------+--------------------------------------+--------------------------------------+-----------+
| 86c068cd-da89-11eb-a185-3da86c6c6bb3 | 86c068cc-da89-11eb-a185-3da86c6c6bb3 | 86c068cc-da89-11eb-a185-3da86c6c6bb3 | 1.1.1.1   |
+--------------------------------------+--------------------------------------+--------------------------------------+-----------+
1 row selected (0.005 seconds)

If I delete and create the same tables with a query_parallelism = 8, I do not have a SQL error (the parallelism is equal on the 2 tables) BUT the result of the join is empty.

any idea why I get this behavior ?

Answer 1

The problem comes from the SQL client : it has to be aware of the parallelism.

On DBeaver, I had to enable ignite.jdbc.distributedJoins in the connection properties to make the request works properly.