Paul Rogers created IMPALA-7740:
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Summary: Incorrect doc description for nvl2()
Key: IMPALA-7740
URL: https://issues.apache.org/jira/browse/IMPALA-7740
Project: IMPALA
Issue Type: Bug
Components: Docs
Affects Versions: Impala 3.0
Reporter: Paul Rogers
Impala offers the NVL2() function from
[Oracle|https://docs.oracle.com/cd/B28359_01/olap.111/b28126/dml_functions_2049.htm#OLADM625].
A clearer definition is
[here|https://www.techonthenet.com/oracle/functions/nvl2.php]:
{quote}
The syntax for the NVL2 function in Oracle/PLSQL is:
{{NVL2( string1, value_if_not_null, value_if_null )}}
{quote}
Contrast that with the [Impala
description|https://impala.apache.org/docs/build3x/html/topics/impala_conditional_functions.html]:
{quote}
Enhanced variant of the nvl() function. Tests an expression and returns
different result values depending on whether it is NULL or not. _If the first
argument is NULL, returns the second argument. If the first argument is not
NULL, returns the third argument._ Equivalent to the nvl2() function from
Oracle Database.
{quote}
(Emphasis added.) The description is exactly backward. To see this:
{noformat}
select n, nvl2(n, 10, 20) from ints;
+------+---------------------------+
| n | if(n is not null, 10, 20) |
+------+---------------------------+
| NULL | 20 |
| 0 | 10 |
+------+---------------------------+
{noformat}
Hence, the implementation follows Oracle, the documentation is wrong.
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