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https://issues.apache.org/jira/browse/HADOOP-17347?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17257885#comment-17257885
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Rajesh Balamohan commented on HADOOP-17347:
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>> If the read is for the last 8 bytes, read the full file.
Can you plz share details on this? Does this mean that it is going to load 4 MB
(or buffer size) worth of data during footer reads? If so, it would be
expensive for short jobs that rely on footer reads.
> ABFS: Read optimizations
> ------------------------
>
> Key: HADOOP-17347
> URL: https://issues.apache.org/jira/browse/HADOOP-17347
> Project: Hadoop Common
> Issue Type: Sub-task
> Components: fs/azure
> Affects Versions: 3.4.0
> Reporter: Bilahari T H
> Assignee: Bilahari T H
> Priority: Major
> Labels: pull-request-available
> Time Spent: 12h 10m
> Remaining Estimate: 0h
>
> Optimize read performance for the following scenarios
> # Read small files completely
> Files that are of size smaller than the read buffer size can be considered
> as small files. In case of such files it would be better to read the full
> file into the AbfsInputStream buffer.
> # Read last block if the read is for footer
> If the read is for the last 8 bytes, read the full file.
> This will optimize reads for parquet files. [Parquet file
> format|https://www.ellicium.com/parquet-file-format-structure/]
> Both these optimizations will be present under configs as follows
> # fs.azure.read.smallfilescompletely
> # fs.azure.read.optimizefooterread
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