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Posted to issues-all@impala.apache.org by "Daniel Becker (JIRA)" <ji...@apache.org> on 2019/07/08 07:40:00 UTC
[jira] [Reopened] (IMPALA-8710) Increase allowed bit width to 64
for bit packing
[ https://issues.apache.org/jira/browse/IMPALA-8710?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Daniel Becker reopened IMPALA-8710:
-----------------------------------
The implementation introduced a buffer overflow error. The new implementation of the innermost function of bit unpacking (UnpackValue) is simpler in my opinion but if we avoid the buffer overflow, there are significant performance regressions from bit width 9 to 15 for odd bit widths. This seems to be a compiler thing. The modification that introduced the buffer overflow was done to avoid this regression.
> Increase allowed bit width to 64 for bit packing
> ------------------------------------------------
>
> Key: IMPALA-8710
> URL: https://issues.apache.org/jira/browse/IMPALA-8710
> Project: IMPALA
> Issue Type: Sub-task
> Components: Backend
> Reporter: Daniel Becker
> Assignee: Daniel Becker
> Priority: Major
>
> Increase the allowed bit width for bit packing and bit unpacking to 64
> bits. This is needed to support Parquet Delta Encoding.
>
> Also add new methods to BitWriter and BatchedBitReader handling Uleb and
> ZigZag integers for 64 bits.
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