Syed Shameerur Rahman created HIVE-22891:
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Summary: Skip PartitonDesc Extraction In CombineHiveRecord For
Non-LLAP Execution Mode
Key: HIVE-22891
URL: https://issues.apache.org/jira/browse/HIVE-22891
Project: Hive
Issue Type: Task
Reporter: Syed Shameerur Rahman
Assignee: Syed Shameerur Rahman
Fix For: 4.0.0
{code:java}
try {
// TODO: refactor this out
if (pathToPartInfo == null) {
MapWork mrwork;
if (HiveConf.getVar(conf,
HiveConf.ConfVars.HIVE_EXECUTION_ENGINE).equals("tez")) {
mrwork = (MapWork) Utilities.getMergeWork(jobConf);
if (mrwork == null) {
mrwork = Utilities.getMapWork(jobConf);
}
} else {
mrwork = Utilities.getMapWork(jobConf);
}
pathToPartInfo = mrwork.getPathToPartitionInfo();
} PartitionDesc part = extractSinglePartSpec(hsplit);
inputFormat = HiveInputFormat.wrapForLlap(inputFormat, jobConf, part);
} catch (HiveException e) {
throw new IOException(e);
}
{code}
The above piece of code in CombineHiveRecordReader.java was introduced in
HIVE-15147. This overwrites inputFormat based on the PartitionDesc which is not
required in non-LLAP mode of execution as the method
HiveInputFormat.wrapForLlap() simply returns the previously defined inputFormat
in case of non-LLAP mode. The method call extractSinglePartSpec() has some
serious performance implications. If there are large no. of small files, each
call in the method extractSinglePartSpec() takes approx ~ (2 - 3) seconds.
Hence the same query which runs in Hive 1.x / Hive 2 is way faster than the
query run on latest hive.
{code:java}
2020-02-11 07:15:04,701 INFO [main]
org.apache.hadoop.hive.ql.io.orc.ReaderImpl: Reading ORC rows from
<S3://>2020-02-11
07:15:06,468 WARN [main] org.apache.hadoop.hive.ql.io.CombineHiveRecordReader:
Multiple partitions found; not going to pass a part spec to LLAP IO:
{{logdate=2020-02-03, hour=01, event=win}} and {{logdate=2020-02-03, hour=02,
event=act}}
2020-02-11 07:15:06,468 INFO [main]
org.apache.hadoop.hive.ql.io.CombineHiveRecordReader: succeeded in getting
org.apache.hadoop.mapred.FileSplit{code}
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