Rajesh Balamohan created HIVE-23468:
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Summary: LLAP: Optimise OrcEncodedDataReader to avoid FS init to NN
Key: HIVE-23468
URL: https://issues.apache.org/jira/browse/HIVE-23468
Project: Hive
Issue Type: Improvement
Reporter: Rajesh Balamohan
OrcEncodedDataReader materializes the supplier<fs> to check if it is a HDFS
system or not. This causes unwanted call to NN even in cases when cache is
completely warmed up.
[https://github.com/apache/hive/blob/master/llap-server/src/java/org/apache/hadoop/hive/llap/io/encoded/OrcEncodedDataReader.java#L540]
[https://github.com/apache/hive/blob/9f40d7cc1d889aa3079f3f494cf810fabe326e44/ql/src/java/org/apache/hadoop/hive/ql/io/HdfsUtils.java#L107]
Workaround is to set "hive.llap.io.use.fileid.path=false" to avoid this case.
IO elevator could get 100% cache hit from FileSystem impl in warmed up scenario.
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