ORC-753: [C++] Clear stream state of ColumnReader after seek#645
Merged
xndai merged 1 commit intoapache:masterfrom Feb 27, 2021
Merged
ORC-753: [C++] Clear stream state of ColumnReader after seek#645xndai merged 1 commit intoapache:masterfrom
xndai merged 1 commit intoapache:masterfrom
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@dongjoon-hyun I have split this minor fix from the PPD patch. Please review it when you have time. Thanks! |
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+1, late LGTM. Thank you, @wgtmac . |
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What changes were proposed in this pull request?
C++ ORC ColumnReaders of some types have cached buffer state to issue next I/O. This is fine if we read streams continuously. However, if we try to skip some row groups and seek to a random row group, the cached buffer state is wrong and may lead to undefined behavior. This patch fixes it by clearing all stream states in the ColumnReader.
Why are the changes needed?
This fix is a prerequisite to introduce PPD to C++ ORC reader in that the read pattern requires seeking to any row group.
How was this patch tested?
This is a trivial fix and just make sure it doesn't break any unit test case.