[jira] [Resolved] (IMPALA-4940) DECIMAL V2 multiply result type

["Taras Bobrovytsky (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/IMPALA-4940?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Taras Bobrovytsky resolved IMPALA-4940.
---------------------------------------
    Resolution: Fixed

{code}
commit 6259641077250dcd3360e2e6c2bf9023b201d858
Author: Taras Bobrovytsky <tb...@cloudera.com>
Date:   Thu Jul 6 10:43:34 2017 -0700

    IMPALA-4939, IMPALA-4940: Decimal V2 multiplication

    Implement the new DECIMAL return type rules for multiply expressions,
    active when query option DECIMAL_V2=1. The algorithm for determining
    the type of the result of multiplication is described in the JIRA.
{code}

> DECIMAL V2 multiply result type
> -------------------------------
>
>                 Key: IMPALA-4940
>                 URL: https://issues.apache.org/jira/browse/IMPALA-4940
>             Project: IMPALA
>          Issue Type: Bug
>          Components: Frontend
>    Affects Versions: Impala 2.9.0
>            Reporter: Dan Hecht
>            Assignee: Taras Bobrovytsky
>
> Similar to IMPALA-4370 but for multiply.  Impala's current multiply result type is:
> {code}
> rP = P1 + P2
> rS = S1 + S2
> If (rP > 38) then
>    rP = 38
>    rS = min(38, rS)
> {code}
> The proposed result type under V2 is:
> {code}
> rP = P1 + P2 + 1
> rS = S1 + S2
> // createAdjustedDecimalType()
> If (rP > 38) then
>    minS = min(rS, 6)
>    rS = rS - (rP - 38)  
>    rS = max(minS, rS)
>    rP = 38
> {code}
> However, in order for this to be useful, we need to fix IMPALA-4939. Otherwise, we can't actually compute values that need the new result type anyway.



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