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https://issues.apache.org/jira/browse/HIVE-20509?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16611768#comment-16611768
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Barnabas Maidics commented on HIVE-20509:
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[~gopalv] can you take a look at the patch?
I don't really understand how we would win 500 bytes. Removing the unnecessary
nulls resulted 72 bytes less memory per partition. It makes sense, since a
null is 8 byte and there were 9 nulls.
> Plan: fix wasted memory in plans with large partition counts
> ------------------------------------------------------------
>
> Key: HIVE-20509
> URL: https://issues.apache.org/jira/browse/HIVE-20509
> Project: Hive
> Issue Type: Bug
> Components: Query Planning
> Reporter: Gopal V
> Assignee: Barnabas Maidics
> Priority: Minor
> Labels: newbie
> Attachments: HIVE-20509.2.patch, HIVE-20509.patch, after.png,
> before.png
>
>
> {code}
> public void addPathToAlias(Path path, String newAlias){
> ArrayList<String> aliases = pathToAliases.get(path);
> if (aliases == null) {
> aliases = new ArrayList<>();
> StringInternUtils.internUriStringsInPath(path);
> pathToAliases.put(path, aliases);
> }
> aliases.add(newAlias.intern());
> }
> {code}
> ArrayList::DEFAULT_CAPACITY is 10, so this wastes 500 bytes of memory due to
> the {{new ArrayList<>();}}.
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