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From "Mamta A. Satoor (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (DERBY-1960) Handle null compilation schema to improve statement cache mechanism
Date Tue, 25 Jun 2013 05:06:22 GMT

     [ https://issues.apache.org/jira/browse/DERBY-1960?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel

Mamta A. Satoor updated DERBY-1960:

    Urgency: Normal
     Labels: derby_triage10_11  (was: )
> Handle null compilation schema to improve statement cache mechanism
> -------------------------------------------------------------------
>                 Key: DERBY-1960
>                 URL: https://issues.apache.org/jira/browse/DERBY-1960
>             Project: Derby
>          Issue Type: Improvement
>          Components: SQL
>    Affects Versions:
>         Environment: Any
>            Reporter: Yip Ng
>              Labels: derby_triage10_11
> A compilation schema with null value indicates that the trigger action statement text
does not depend on the current schema. This means:
> 1. It is safe to compile this statement in any schema since there is no dependency with
>     the CURRENT SCHEMA. i.e.: All relevent fields are qualified with a specific schema.
> 2. The statement cache mechanism can utilize this piece of information to enable
>     better statement plan sharing across different schemas; thus, avoiding unnecessary
>     statement compilation. 
> This is a follow-up work of DERBY-630.  To improve the statement cache mechanism, the
system needs to handle the null compilation schema in statement preparation logic.  It may
require some work on the SQL parser to determine whether the compiled statement depends on
the CURRENT SCHEMA or not, so that the compilation schema can be properly set. 

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