[jira] [Closed] (IMPALA-7739) Errata in documentation of decode() method

["Alex Rodoni (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/IMPALA-7739?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Alex Rodoni closed IMPALA-7739.
-------------------------------
       Resolution: Fixed
    Fix Version/s: Impala 3.1.0

> Errata in documentation of decode() method
> ------------------------------------------
>
>                 Key: IMPALA-7739
>                 URL: https://issues.apache.org/jira/browse/IMPALA-7739
>             Project: IMPALA
>          Issue Type: Improvement
>          Components: Docs
>    Affects Versions: Impala 3.0
>            Reporter: Paul Rogers
>            Assignee: Alex Rodoni
>            Priority: Minor
>             Fix For: Impala 3.1.0
>
>
> Consider the description of {{decode()}} in [the docs|https://impala.apache.org/docs/build3x/html/topics/impala_conditional_functions.html]. Original text:
> {quote}
> decode(type expression, type search1, type result1 [, type search2, type result2 ...] [, type default] )
> Purpose: Compares an expression to one or more possible values, and returns a corresponding result when a match is found.
> Return type: same as the initial argument value, except that integer values are promoted to BIGINT and floating-point values are promoted to DOUBLE; use CAST() when inserting into a smaller numeric column
> Usage notes:
> * Can be used as shorthand for a CASE expression.
> * The original expression and the search expressions must of the same type or convertible types. * The result expression can be a different type, but all result expressions must be of the same type.
> * Returns a successful match If the original expression is NULL and a search expression is also NULL. the
> * Returns NULL if the final default value is omitted and none of the search expressions match the original expression.
> {quote}
> Revise:
> * Remove “type” prefix for arguments (here and in all functions), it really adds no value and is actually confusing because the argument is not a type, it is a value.
> * Usage notes: Comparison is done using the IS NOT DISTINCT (<=>) operator: this NULL can be used as a search condition.
> * Since this is a list, great between the two items in the second item in usage.
> * The third item has a dangling “the” at the end.
> * Reword the fourth item: “If none of the search expressions match the expression, then returns the default (if given) or NULL (if no default is given.)”
> Suggested revised text:
> Purpose: Compares an expression to one or more possible values using the IS NOT DISTINCT operator, and returns a corresponding result when a match is found.
> Usage notes:
> * Can be used as shorthand for a CASE expression.
> * The expression and the search expressions must of the same type or convertible types.
> * The result expression can be a different type, but all result expressions must be of the same type.
> * Returns a successful match If the original expression is NULL and a search expression is also NULL. (Uses IS NOT DISTINCT to do the comparison.)
> * NULL can be used as a search expression.
> * Returns NULL if the final default value is omitted and none of the search expressions match the original expression.



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