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Posted to dev@hive.apache.org by "Mostafa Mokhtar (JIRA)" <ji...@apache.org> on 2014/09/05 02:21:24 UTC
[jira] [Created] (HIVE-7990) With fetch column stats disabled
number of elements in grouping set is not taken into account
Mostafa Mokhtar created HIVE-7990:
-------------------------------------
Summary: With fetch column stats disabled number of elements in grouping set is not taken into account
Key: HIVE-7990
URL: https://issues.apache.org/jira/browse/HIVE-7990
Project: Hive
Issue Type: Bug
Components: File Formats
Affects Versions: 0.13.1
Environment: Loading into orc
Reporter: Mostafa Mokhtar
Assignee: Prasanth J
Fix For: 0.14.0
When loading into an un-paritioned ORC table WriterImpl$StructTreeWriter.write method is synchronized.
When hive.optimize.sort.dynamic.partition is enabled the current thread will be the only writer and the synchronization is not needed.
Also checking for memory per row is an over kill , this can be done per 1K rows or such
{code}
public void addRow(Object row) throws IOException {
synchronized (this) {
treeWriter.write(row);
rowsInStripe += 1;
if (buildIndex) {
rowsInIndex += 1;
if (rowsInIndex >= rowIndexStride) {
createRowIndexEntry();
}
}
}
memoryManager.addedRow();
}
{code}
This can improve ORC load performance by 7%
{code}
Stack Trace Sample Count Percentage(%)
WriterImpl.addRow(Object) 5,852 65.782
WriterImpl$StructTreeWriter.write(Object) 5,163 58.037
MemoryManager.addedRow() 666 7.487
MemoryManager.notifyWriters() 648 7.284
WriterImpl.checkMemory(double) 645 7.25
WriterImpl.flushStripe() 643 7.228
WriterImpl$StructTreeWriter.writeStripe(OrcProto$StripeFooter$Builder, int) 584 6.565
{code}
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