[jira] [Closed] (TRAFODION-21) The existing plan is not reused even when a HQC constant can fit the corresponding parameter

["Qifan Chen (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/TRAFODION-21?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Qifan Chen closed TRAFODION-21.
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    Resolution: Fixed

> The existing plan is not reused even when a HQC constant can fit the corresponding parameter
> --------------------------------------------------------------------------------------------
>
>                 Key: TRAFODION-21
>                 URL: https://issues.apache.org/jira/browse/TRAFODION-21
>             Project: Apache Trafodion
>          Issue Type: Bug
>            Reporter: Qifan Chen
>              Labels: performance
>
> When no histogram interval check is necessary, an existing HQC query plan is not reused even when a HQC constant can fit the corresponding HQC parameter by the type. 
> The problem is with HQC caching of meta-data queries such as the following one:
> select text from TRAFODION.\"_MD_\".TEXT where text_uid = 1395060834168658846 and text_type = 4 and sub_id = 10 for read committed access order by seq_num",
> Column TEXT_UID is of LargeInt with a magnitude of 189. The constant 1395060834168658846 is parsed into a numeric constant value with a magnitude of 190.  The existing code calls natype->errorsCanOccur() which returns true because the constant's magnitude of 190 is larger than target type's magnitude of 189. Since the constant does not fit LargeInt, caching reuse is impossible. 
> The correct approach is to call Constant::canBeSafelyCoercedTo() instead. Here the constant 1395060834168658846 fits comfortably within a LargeInt, and therefore the HQC cached query plan can be reused. 
> With the fix, compGeneral/TEST042 passes. 



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