[jira] [Updated] (CALCITE-1165) VolcanoCost comparing floating point numbers might cause problems in a few places

["Julian Hyde (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/CALCITE-1165?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Julian Hyde updated CALCITE-1165:
---------------------------------
    Summary: VolcanoCost comparing floating point numbers might cause problems in a few places  (was: VocanoCost comparing floating point numbers might cause problems in a few places)

> VolcanoCost comparing floating point numbers might cause problems in a few places
> ---------------------------------------------------------------------------------
>
>                 Key: CALCITE-1165
>                 URL: https://issues.apache.org/jira/browse/CALCITE-1165
>             Project: Calcite
>          Issue Type: Bug
>          Components: core
>    Affects Versions: 1.7.0
>            Reporter: Maryann Xue
>            Assignee: Julian Hyde
>            Priority: Minor
>
> The floating number comparison can be inaccurate and can break some logic in VolcanoPlanner. For example,
> 1) VolcanoPlanner.validate(): 
> {code}
>         for (RelNode rel : subset.getRels()) {
>           RelOptCost relCost = getCost(rel, mq);
>           if (relCost.isLt(subset.bestCost)) {
>             throw new AssertionError(
>                 "rel [" + rel.getDescription()
>                 + "] has lower cost " + relCost
>                 + " than best cost " + subset.bestCost
>                 + " of subset [" + subset.getDescription() + "]");
>           }
>         }
> {code}
> 2) VolcanoPlanner.getCost(RelNode, RelMetadataQuery)
> {code}
>     RelOptCost cost = mq.getNonCumulativeCost(rel);
>     if (!zeroCost.isLt(cost)) {
>       // cost must be positive, so nudge it
>       cost = costFactory.makeTinyCost();
>     }
> {code}



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