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https://issues.apache.org/jira/browse/HIVE-4078?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13593107#comment-13593107
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Gopal V commented on HIVE-4078:
-------------------------------
This is not a pair of operations as previously assumed, but does the
deserialization repeatedly for each alias
{code}
for (int i = 0; i < numAliases; i++) {
...
// create map join task and set big table as i
ObjectPair<MapRedTask, String> newTaskAlias =
convertTaskToMapJoinTask(xml, i);
MapRedTask newTask = newTaskAlias.getFirst();
bigTableAlias = newTaskAlias.getSecond();
}
{code}
> Remove the serialize-deserialize pair in CommonJoinResolver
> -----------------------------------------------------------
>
> Key: HIVE-4078
> URL: https://issues.apache.org/jira/browse/HIVE-4078
> Project: Hive
> Issue Type: Bug
> Components: Query Processor
> Reporter: Gopal V
> Assignee: Gopal V
> Attachments: HIVE-4078-20130227.patch, HIVE-4078.patch
>
>
> CommonJoinProcessor tries to clone a MapredWork while attempting a conversion
> to a map-join
> {code}
> // deep copy a new mapred work from xml
> InputStream in = new ByteArrayInputStream(xml.getBytes("UTF-8"));
> MapredWork newWork = Utilities.deserializeMapRedWork(in,
> physicalContext.getConf());
> {code}
> which is a very heavy operation memory wise & cpu-wise.
> Instead of cloning via XMLEncoder, it is faster to use BeanUtils.cloneBean()
> which is following same data paths (get/set bean methods) instead.
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