[jira] [Created] (TINKERPOP-2490) RangeGlobalStep touches next traverser when high limit is already hit

["Guo Junshi (Jira)" <ji...@apache.org>]

Guo Junshi created TINKERPOP-2490:
-------------------------------------

             Summary: RangeGlobalStep touches next traverser when high limit is already hit
                 Key: TINKERPOP-2490
                 URL: https://issues.apache.org/jira/browse/TINKERPOP-2490
             Project: TinkerPop
          Issue Type: Bug
          Components: process
    Affects Versions: 3.4.8
            Reporter: Guo Junshi


In FilterStep, the processNextStart() method will first retrieve next traverser and then apply filtering logic. But for RangleGlobalStep, if high limit is already hit, there will be no need to get next traverser.
{code:java}
@Override
protected Traverser.Admin<S> processNextStart() {
    while (true) {
        final Traverser.Admin<S> traverser = this.starts.next();
        if (this.filter(traverser))
            return traverser;
    }
}
{code}
An example would be limit step: g.V().limit(1). This query will touch 2 vertices although only 1 vertex will be returned.

This extra data loading will cause performance defects if DB data loading is involved. It is not a functionality bug, but for better performance, we'd better check high range limit first before touching next traversal.



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