Question about SINGLE rules configuration

[jpenalver10]

Hi, I've a questions regarding the SINGLE table configuration, that are not clear for me reading the documentation and making tests.

Regarding this configuration (using PostgreSQL):

rules:
  - !SINGLE
    tables:
      - main.outbox_dm_tables.*
      - main.db_sharding.*
      - main.non-existing
    defaultDataSource: main

I want to do some questions about the definition format of tables:

• main.outbox_dm_tables.* this would means "All tables from outbox_dm_tables schema goes to main shard"?
• main.db_sharding.sharding_tenant_config this would means "Only the table sharding_tenant_config from db_sharding schema goes to main shard"?
• As I know, the SINGLE rules are the default beahviour for all tables that are not defined in other ways (not SHARDING etc) and I have defined a default data source. It means that all tables in another schema (suppose infrastructure) will be routing by default to main shard? In my config this happens when I add this rule main.non-existing, that is intentionally incorrect, so all tables in a infrastructure schema are routing to default, but if I removed main.non-existing the tables can't be located by ShardingSphere.

Caused by: org.apache.shardingsphere.infra.exception.kernel.metadata.TableNotFoundException: Table or view 'qrtz_LOCKS' does not exist.
	at org.apache.shardingsphere.infra.binder.engine.segment.dml.from.type.SimpleTableSegmentBinder.lambda$checkTableExists$12(SimpleTableSegmentBinder.java:178)
	at org.apache.shardingsphere.infra.exception.core.ShardingSpherePreconditions.checkState(ShardingSpherePreconditions.java:44)
	at org.apache.shardingsphere.infra.binder.engine.segment.dml.from.type.SimpleTableSegmentBinder.checkTableExists(SimpleTableSegmentBinder.java:178)
	at org.apache.shardingsphere.infra.binder.engine.segment.dml.from.type.SimpleTableSegmentBinder.bind(SimpleTableSegmentBinder.java:90)
	at org.apache.shardingsphere.infra.binder.engine.segment.dml.from.TableSegmentBinder.bind(TableSegmentBinder.java:57)
	at org.apache.shardingsphere.infra.binder.engine.statement.dml.SelectStatementBinder.lambda$bind$1(SelectStatementBinder.java:64)
	at java.base/java.util.Optional.map(Optional.java:260)
	at org.apache.shardingsphere.infra.binder.engine.statement.dml.SelectStatementBinder.bind(SelectStatementBinder.java:64)

Thank you so much

[terrymanu]

Issue Understanding

• Config is PostgreSQL style !SINGLE with main.outbox_dm_tables., main.db_sharding., main.non-existing, defaultDataSource: main. Expectation: other schemas (e.g., infrastructure) should route to main by default. When main.non-existing is removed, queries on infrastructure.qrtz_LOCKS fail with TableNotFoundException.

Root Cause

• Single-table loading is manual since 5.4.0; tables not listed under tables: are not auto-loaded, so binder sees them as nonexistent.
• defaultDataSource only decides where CREATE TABLE for single tables lands; it does not auto-enroll existing tables.
• The entries you listed cover only outbox_dm_tables and db_sharding schemas. infrastructure is not loaded, so qrtz_LOCKS is rejected.
• main.non-existing (two segments) is parsed in PostgreSQL mode as “dataSource main, schema wildcard *, table=non-existing”, which effectively loads all schemas on main, so it appears to work—but it’s accidental, not intended behavior.

Analysis

• Official syntax (PostgreSQL) is three segments: ds.schema.table, ds.schema., ds.., or ..; see http://shardingsphere.apache.org/document/current/en/user-manual/shardingsphere-jdbc/yaml-config/rules/single/
• Because single-table metadata is not auto-loaded, any table not matched by the configured patterns (and not handled by other rules like sharding/encryption) triggers TableNotFoundException during bind.
• What you’re seeing aligns with the design rather than a routing bug.

Conclusion

Configure explicit coverage for the schemas you want managed, e.g., add main.infrastructure.* or use main../..* if you intend to load all single tables on main. Relying on defaultDataSource alone will not auto-load existing tables.