thswlsqls opened a new issue, #8753: URL: https://github.com/apache/paimon/issues/8753
**Search before asking** - [x] I searched in the [issues](https://github.com/apache/paimon/issues) and found nothing similar. **Paimon version** master @ 345526e26 (2.0-SNAPSHOT) **Compute Engine** Engine-agnostic (core) **Minimal reproduce step** ```java SchemaChange a = SchemaChange.dropColumn(new String[] {"outer", "inner"}); SchemaChange b = SchemaChange.dropColumn(new String[] {"outer", "inner"}); a.equals(b); // true a.hashCode() == b.hashCode(); // false ``` Same for `SchemaChange.addColumn`, `renameColumn`, `updateColumnType` and `updateColumnDefaultValue`. **What doesn't meet your expectations?** These five nested classes in `paimon-api/src/main/java/org/apache/paimon/schema/SchemaChange.java` compare `String[] fieldNames` with `Arrays.equals` (content) but hash it with `Objects.hashCode` (array identity). Equal instances then produce different hash codes, breaking the `Object.hashCode` contract for a `@Public` API: hash-based containers (`HashSet`, `HashMap` key, `distinct()`) silently fail to match equal changes. **Anything else?** `UpdateColumnNullability` and `UpdateColumnComment` in the same file already use `Arrays.hashCode` — the fix is to align the other five. Same defect class as merged PR #8518 (`FunctionChange.UpdateDefinition.hashCode`). **Are you willing to submit a PR?** - [x] I'm willing to submit a PR! -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected]
