Incorrent result when query using lessThan or lessOrEqual for a String field with @Index(type: IndexType.value)

[lokingwei]

When create a IndexType.value for a string field, and query using lessOrEqual and lessThan with the value larger than then last record, eg \uffff, the query return zero record instead of all record

reproduce repo: https://github.com/lokingwei/objectbox_string_lessthan

@Entity()
class Doc {
  int? id;

  @Index(type: IndexType.value)
  String key;
  Doc({
    required this.key,
  });
}

box.put(Doc(key: 'b'));
box.put(Doc(key: 'c'));
box.put(Doc(key: 'd'));

// this line is corrent
expect(box.query(Doc_.key.lessOrEqual('d')).build().find(), hasLength(3));
// expected result to be 3 but return 0
expect(box.query(Doc_.key.lessOrEqual('e')).build().find(), hasLength(3));

[greenrobot-team]

Thanks for the detailed report and example repo!

~I think less and greater is only properly defined for integers, not sure if this is even supposed to work with strings.~ It's supposed to work as explicitly added for strings.

Anyhow, I guess a query should return the same results regardless if an index is used or not.

[greenrobot-team]

@greenrobot OK, confirmed and more details:

• only if VALUE index is used, works fine with hash-based index.
• affects only less and less or equal, greater (or equal) are fine.
• if explicitly making the condition case insensitive (which should prevent using the index) test succeeds.
• can reproduce in Java, so appears to be a core database issue.

Edit: added internal integration test for Java to repro.

[greenrobot]

affects only less, less or equal

You're saying that "greater than" and "greater or equal" work (with an index)?

[greenrobot-team]

You're saying that "greater than" and "greater or equal" work (with an index)?

To also update here (there is an internal issue for this): yes.

[greenrobot-team]

We have released version 2.3.0 which resolves this issue. Please update using flutter pub upgrade (or dart pub upgrade for Dart Native projects).

Thanks again!