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Posted to issues@calcite.apache.org by "Jiajun Xie (Jira)" <ji...@apache.org> on 2022/04/12 01:15:00 UTC

[jira] [Updated] (CALCITE-5091) RelMdRowCount can return more accurate rowCount when fetch is deterministic and offset is dynamic

     [ https://issues.apache.org/jira/browse/CALCITE-5091?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Jiajun Xie updated CALCITE-5091:
--------------------------------
    Description: 
The sql from https://issues.apache.org/jira/browse/CALCITE-5048
{code:java}
select * from emp order by ename limit 1 offset ?
{code}

*RelMdRowCount#getRowCount* will return 14d, because it always return rowCount when offset is dynamic.
{code:java}
    if (rel.offset instanceof RexDynamicParam) {
      return rowCount;
    }
{code}

Obviously, rowCount will not exceed 1 because *LIMIT 1*. We can improve it.

  was:
The sql from https://issues.apache.org/jira/browse/CALCITE-5048
{code:java}
select * from emp order by ename limit 1 offset ?
{code}

*RelMdRowCount#getRowCount* will return 14d, because it always return rowCount when offset is dynamic.
{code:java}
    if (rel.offset instanceof RexDynamicParam) {
      return rowCount;
    }
{code}

Obviously, rowCount will not exceed 1 because* LIMIT 1*. We can improve it.


> RelMdRowCount can return more accurate rowCount when fetch is deterministic and offset is dynamic
> -------------------------------------------------------------------------------------------------
>
>                 Key: CALCITE-5091
>                 URL: https://issues.apache.org/jira/browse/CALCITE-5091
>             Project: Calcite
>          Issue Type: Improvement
>          Components: core
>    Affects Versions: 1.30.0
>            Reporter: Jiajun Xie
>            Assignee: Jiajun Xie
>            Priority: Minor
>
> The sql from https://issues.apache.org/jira/browse/CALCITE-5048
> {code:java}
> select * from emp order by ename limit 1 offset ?
> {code}
> *RelMdRowCount#getRowCount* will return 14d, because it always return rowCount when offset is dynamic.
> {code:java}
>     if (rel.offset instanceof RexDynamicParam) {
>       return rowCount;
>     }
> {code}
> Obviously, rowCount will not exceed 1 because *LIMIT 1*. We can improve it.



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