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https://issues.apache.org/jira/browse/IMPALA-11081?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Quanlong Huang updated IMPALA-11081:
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Target Version: Impala 4.1.2
> Partition key scan optimization may return incorrect results when partition
> file have more than one block
> ---------------------------------------------------------------------------------------------------------
>
> Key: IMPALA-11081
> URL: https://issues.apache.org/jira/browse/IMPALA-11081
> Project: IMPALA
> Issue Type: Bug
> Affects Versions: Impala 4.0.0
> Reporter: carolinchen
> Assignee: YifanZhang
> Priority: Critical
>
> 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 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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