terrymanu commented on issue #34889:
URL:
https://github.com/apache/shardingsphere/issues/34889#issuecomment-3642560451
## Problem Understanding
- In 5.5.2 (JDBC), two logical tables order_main and order_main_hint share
the same actualDataNodes (ds$->{0..2}.order_main_$->{0..999}), and startup
fails with “Same actual data node cannot be configured in multiple logic tables
in same database…”. It worked in 5.2.1
but is blocked after upgrade.
## Root Cause
- 5.5.2 introduces a pre-checker ShardingRuleChecker, which runs
checkUniqueActualDataNodesInTableRules() (see
features/sharding/core/src/main/java/org/apache/shardingsphere/sharding/rule/checker/ShardingRuleChecker.java).
It requires the first actual data node of each
logical table to be unique within the same database. Both logical tables
start with ds0.order_main_0, so DuplicateShardingActualDataNodeException is
raised. This is a stricter config validation change, not a runtime bug.
## Analysis
- ShardingSphere’s intended usage is “one physical table set belongs to
one logical table.” Reusing the same physical tables across multiple logical
tables creates ambiguity in metadata, binding-table checks, and
routing/rewriting caches, so 5.5.2 rejects it during
rule assembly.
- Using a second logical table to switch to a Hint sharding strategy over
the same physical tables conflicts with this constraint. The recommended
approach is to keep a single logical table and use a custom sharding algorithm
that routes based on Hint or column values,
rather than creating another logical table name pointing to the same
physical tables.
- Relevant official docs (these describe config and algorithms, though not
this specific restriction):
- Sharding YAML config (tables and sharding strategies):
https://shardingsphere.apache.org/document/current/en/user-manual/shardingsphere-jdbc/yaml-config/rules/sharding/#tables
- Sharding strategies (standard/Hint):
https://shardingsphere.apache.org/document/current/en/user-manual/common-config/builtin-algorithm/sharding/
## Conclusion
- This is a configuration tightening in 5.5.2 and the scenario is no
longer supported; it is not a framework bug. Suggestions:
- Keep a single logical table and implement routing inside your custom
sharding algorithm using Hint or column values to achieve the desired behavior
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