[jira] [Resolved] (IMPALA-12076) Potential performance improvement using ZSTD's ZSTD_decompressDCtx interface

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

     [ https://issues.apache.org/jira/browse/IMPALA-12076?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Joe McDonnell resolved IMPALA-12076.
------------------------------------
    Fix Version/s: Impala 4.4.0
         Assignee: Joe McDonnell
       Resolution: Fixed

> Potential performance improvement using ZSTD's ZSTD_decompressDCtx interface
> ----------------------------------------------------------------------------
>
>                 Key: IMPALA-12076
>                 URL: https://issues.apache.org/jira/browse/IMPALA-12076
>             Project: IMPALA
>          Issue Type: Improvement
>          Components: Backend
>    Affects Versions: Impala 4.3.0
>            Reporter: Joe McDonnell
>            Assignee: Joe McDonnell
>            Priority: Major
>             Fix For: Impala 4.4.0
>
>
> In ORC-639, they note that ZSTD's simple interface initializes the context on each call to ZSTD_decompress(). When calling ZSTD_decompress() many times, it is better to allocate the context once and use the ZSTD_decompressDCtx() interface to avoid the repeated initialization.
> The ZSTD code mentions that here:
>  
> {noformat}
> /*= Decompression context
>  *  When decompressing many times,
>  *  it is recommended to allocate a context only once,
>  *  and re-use it for each successive compression operation.
>  *  This will make workload friendlier for system's memory.
>  *  Use one context per thread for parallel execution. */
> typedef struct ZSTD_DCtx_s ZSTD_DCtx;{noformat}
> We should investigate using this for decompress.h/.cc's ZstandardDecompressor. We already do that for the streaming decompression mode, but this should also apply to block decompression. Something similar is possible for compression as well.
>  



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