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https://issues.apache.org/jira/browse/IGNITE-25977?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Konstantin Orlov reassigned IGNITE-25977:
-----------------------------------------
Assignee: Konstantin Orlov
> Sql. Query optimizer hangs while preparing UNION with huge number of tables
> ---------------------------------------------------------------------------
>
> Key: IGNITE-25977
> URL: https://issues.apache.org/jira/browse/IGNITE-25977
> Project: Ignite
> Issue Type: Bug
> Components: sql ai3
> Reporter: Konstantin Orlov
> Assignee: Konstantin Orlov
> Priority: Major
> Labels: ignite-3
>
> Take a look at test case below:
> {code}
> // org.apache.ignite.internal.sql.engine.planner.UnionPlannerTest
> @Test
> void unionAllHugeNumberOfTables() throws Exception {
> int tablesCount = 50;
> IgniteTable[] tables = IntStream.range(0, tablesCount)
> .mapToObj(i -> createTestTable("TABLE_" + i))
> .toArray(IgniteTable[]::new);
> IgniteSchema schema = createSchema(tables);
> String query = IntStream.range(0, tablesCount)
> .mapToObj(i -> "SELECT \n"
> + " 'label_" + i + "' As l_name, \n"
> + " CASE WHEN EXISTS (\n"
> + " SELECT 1 FROM table_" + i + "\n"
> + " ) then true ELSE false END AS has_data")
> .collect(Collectors.joining(" UNION "));
>
> assertPlan(query, schema, node -> true);
> }
> {code}
> This test fails with {{java.lang.OutOfMemoryError}} due to current
> implementations of
> {{org.apache.ignite.internal.sql.engine.trait.TraitUtils#combinations}}: it
> prepares full enumeration of all possible combinations of input traits. The
> problem arises on relations with big number of inputs. In this particular
> case there are 50 inputs, and every one have 2 variations of trait set, which
> gives as 2^50 possible combinations. Let's introduce an upper bound for
> combinations complexity for the exhaustive enumeration.
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