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https://issues.apache.org/jira/browse/HIVE-5298?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13779059#comment-13779059
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Xuefu Zhang commented on HIVE-5298:
-----------------------------------
[~ashutoshc] The issue isn't with pathToPartInfo. The issue is in original code
{code}
try {
for (String onefile : conf.getPathToAliases().keySet()) {
PartitionDesc pd = conf.getPathToPartitionInfo().get(onefile);
{code}
where conf.getPathToAliases().keySet() returns all files that belong to the
table. Thus, the for loop has to go thru each file in the table to get
partition metadata (using pathToPartInfo()). However, it's only necessary to do
so per partition, and a partition may have any number of files.
Let me know if more info is needed.
> AvroSerde performance problem caused by HIVE-3833
> -------------------------------------------------
>
> Key: HIVE-5298
> URL: https://issues.apache.org/jira/browse/HIVE-5298
> Project: Hive
> Issue Type: Improvement
> Components: Query Processor
> Affects Versions: 0.11.0
> Reporter: Xuefu Zhang
> Assignee: Xuefu Zhang
> Fix For: 0.13.0
>
> Attachments: HIVE-5298.1.patch, HIVE-5298.patch
>
>
> HIVE-3833 fixed the targeted problem and made Hive to use partition-level
> metadata to initialize object inspector. In doing that, however, it goes thru
> every file under the table to access the partition metadata, which is very
> inefficient, especially in case of multiple files per partition. This causes
> more problem for AvroSerde because AvroSerde initialization accesses schema,
> which is located on file system. As a result, before hive can process any
> data, it needs to access every file for a table, which can take long enough
> to cause job failure because of lack of job progress.
> The improvement can be made so that partition metadata is only access once
> per partition.
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