[jira] [Closed] (IMPALA-11087) Partition key scan optimization may return incorrect results when partition file have more than one block

["carolinchen (Jira)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/IMPALA-11087?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

carolinchen closed IMPALA-11087.
--------------------------------
    Resolution: Fixed

> Partition key scan optimization may return incorrect results when partition file have more than one block
> ---------------------------------------------------------------------------------------------------------
>
>                 Key: IMPALA-11087
>                 URL: https://issues.apache.org/jira/browse/IMPALA-11087
>             Project: IMPALA
>          Issue Type: Bug
>            Reporter: carolinchen
>            Assignee: carolinchen
>            Priority: Major
>
> In https://issues.apache.org/jira/browse/IMPALA-8834  will only generate one scan range for partition key's scan, but it may cause wrong result. 
> In this case, when a partition file with more than one block:
>  # The planner will only transforms the first block into TScanRange,  which does not include footer.
>  # The backend can't find the split with the footer,  so that can neither parse the footer nor do the scan.
> so that  the paritition key scan's result will be incorrect. 
>  
> see this snippet in HdfsScanNode.java:
>  
> {code:java}
> private Pair<Boolean, Long> transformBlocksToScanRanges(
>     FeFsPartition partition, FileDescriptor fileDesc, 
>     boolean fsHasBlocks, long scanRangeBytesLimit, 
>     Analyzer analyzer) { 
>     for (int i = 0; i < fileDesc.getNumFileBlocks(); ++i) {
>       // Only generate one scan range for partition key scans.      
>       if (isPartitionKeyScan_) break;
>     }
> }{code}
> In FE,  if file with more than one block do partition key scan,  transformBlocksToScanRanges will not include footer range. 
>  
> see this snippet in hdfs-scanner.cc:
>  
> {code:java}
> /// Issue just the footer range for each file. This function is only used /// in parquet and orc scanners. We'll then parse the footer and pick out /// the columns we want.  
> Status HdfsScanner::IssueFooterRanges(HdfsScanNodeBase* scan_node, 
>     const THdfsFileFormat::type& file_type, 
>     const std::vector<HdfsFileDesc*>& files) {
>     // Try to find the split with the footer.    
>     ScanRange* footer_split = FindFooterSplit(files[i]);
> }{code}
> In BE, there no footer split won't add range to do the scan. 
>  
>  



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