[jira] [Resolved] (IMPALA-12373) Implement Small String Optimization for StringValue

["Zoltán Borók-Nagy (Jira)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/IMPALA-12373?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Zoltán Borók-Nagy resolved IMPALA-12373.
----------------------------------------
    Fix Version/s: Impala 4.4.0
       Resolution: Fixed

> Implement Small String Optimization for StringValue
> ---------------------------------------------------
>
>                 Key: IMPALA-12373
>                 URL: https://issues.apache.org/jira/browse/IMPALA-12373
>             Project: IMPALA
>          Issue Type: Improvement
>            Reporter: Zoltán Borók-Nagy
>            Assignee: Zoltán Borók-Nagy
>            Priority: Major
>              Labels: Performance
>             Fix For: Impala 4.4.0
>
>         Attachments: small_string.cpp
>
>
> Implement Small String Optimization for StringValue.
> Current memory layout of StringValue is:
> {noformat}
>   char* ptr;  // 8 byte
>   int len;    // 4 byte
> {noformat}
> For small strings with size up to 8 we could store the string contents in the bytes of the 'ptr'. Something like that:
> {noformat}
>   union {
>     char* ptr;
>     char small_buf[sizeof(ptr)];
>   };
>   int len;
> {noformat}
> Many C++ string implementations use the {{Small String Optimization}} to speed up work with small strings. For example:
> {code:java}
> Microsoft STL, libstdc++, libc++, Boost, Folly.{code}



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