[jira] [Commented] (JCR-2892) Large fetch sizes have potentially deleterious effects on VM memory requirements when using Oracle

["Jukka Zitting (Commented) (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/JCR-2892?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13150490#comment-13150490 ] 

Jukka Zitting commented on JCR-2892:
------------------------------------

Merged to the 2.2 branch in revision 1202191.
                
> Large fetch sizes have potentially deleterious effects on VM memory requirements when using Oracle
> --------------------------------------------------------------------------------------------------
>
>                 Key: JCR-2892
>                 URL: https://issues.apache.org/jira/browse/JCR-2892
>             Project: Jackrabbit Content Repository
>          Issue Type: Bug
>          Components: jackrabbit-core, sql
>    Affects Versions: 2.2.2
>         Environment: Oracle 10g+
>            Reporter: Christopher Elkins
>            Assignee: Claus Köll
>             Fix For: 2.2.10, 2.3.2
>
>         Attachments: JCR-2892.patch, oracleFetchSize.patch
>
>
> Since Release 10g, Oracle JDBC drivers use the fetch size to allocate buffers for caching row data.
> cf. http://www.oracle.com/technetwork/database/enterprise-edition/memory.pdf
> r1060431 hard-codes the fetch size for all ResultSet-returning statements to 10,000. This value has significant, potentially deleterious, effects on the heap space required for even moderately-sized repositories. For example, the BUNDLE table (from 'oracle.ddl') has two columns -- NODE_ID raw(16) and BUNDLE_DATA blob -- which require 16 b and 4 kb of buffer space, respectively. This requires a buffer of more than 40 mb [(16+4096) * 10000 = 41120000].
> If the issue described in JCR-2832 is truly specific to PostgreSQL, I think its resolution should be moved to a PostgreSQL-specific ConnectionHelper subclass. Failing that, there should be a way to override this hard-coded value in OracleConnectionHelper.

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