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https://issues.apache.org/jira/browse/JCR-2892?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12995726#comment-12995726
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Thomas Mueller commented on JCR-2892:
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Wow, I would never have thought the Oracle driver actually allocates the
memory... sounds like a really bad idea to do nowadays, but well this is
Oracle. Anyway, if you do have a failing test case, then of course the fetch
size needs to be changed.
> 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
>
> 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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