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Posted to dev@jackrabbit.apache.org by "Thomas Mueller (JIRA)" <ji...@apache.org> on 2011/02/16 08:46:57 UTC
[jira] Resolved: (JCR-2892) Large fetch sizes have potentially
deleterious effects on VM memory requirements when using Oracle
[ https://issues.apache.org/jira/browse/JCR-2892?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Thomas Mueller resolved JCR-2892.
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Resolution: Cannot Reproduce
Do you have a reproducible test case where it uses a lot of memory or even runs out of memory?
As far as I see, the persistence manager only ever selects one row at a time (using a where condition), except for the consistency check, where only the node id is selected. Therefore, I don't see where it could use a lot of memory.
Please re-open if you have a test case where it's actually a problem, or if you can point to the code where many complete rows are selected.
> 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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