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https://issues.apache.org/jira/browse/HIVE-24040?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17209610#comment-17209610
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Zoltan Haindrich commented on HIVE-24040:
-----------------------------------------
{code}
select cast('a' as char(10)) = cast('a ' as varchar(50))
{code}
in psql I got some interesting results:
{code}
select length(cast('a ' as varchar(10))),length(cast('a ' as char(10) )
),cast('a ' as varchar(10))=cast('a ' as char(10) );
length | length | ?column?
--------+--------+----------
2 | 1 | t
{code}
in Hive for the above case the comparision should happen in "string" for which
the lengths are different => will not match
{code}
select length(cast(cast('a' as char(10)) as string)),length(cast(cast('a ' as
varchar(50)) as string))
+------+------+
| _c0 | _c1 |
+------+------+
| 1 | 2 |
+------+------+
{code}
I feel that this is somewhere in the gray zone...will dig into the sql specs...
> Slightly odd behaviour with CHAR comparisons and string literals
> ----------------------------------------------------------------
>
> Key: HIVE-24040
> URL: https://issues.apache.org/jira/browse/HIVE-24040
> Project: Hive
> Issue Type: Bug
> Reporter: Tim Armstrong
> Priority: Major
>
> If t is a char column, this statement behaves a bit strangely - since the RHS
> is a STRING, I would have expected it to behave consistently with other
> CHAR/STRING comparisons, where the CHAR column has its trailing spaces
> removed and the STRING does not have its trailing spaces removed.
> {noformat}
> select count(*) from ax where t = cast('a ' as string);
> {noformat}
> Instead it seems to be treated the same as if it was a plain literal,
> interpreted as CHAR, i.e.
> {noformat}
> select count(*) from ax where t = 'a ';
> {noformat}
> Here are some more experiments I did based on
> https://github.com/apache/hive/blob/master/ql/src/test/queries/clientpositive/in_typecheck_char.q
> that seem to show some inconsistencies.
> {noformat}
> -- Hive version 3.1.3000.7.2.1.0-287 r4e72e59f1c2a51a64e0ff37b14bd396cd4e97b98
> create table ax(s char(1),t char(10));
> insert into ax values ('a','a'),('a','a '),('b','bb');
> -- varchar literal preserves trailing space
> select count(*) from ax where t = cast('a ' as varchar(50));
> +------+
> | _c0 |
> +------+
> | 0 |
> +------+
> -- explicit cast of literal to string removes trailing space
> select count(*) from ax where t = cast('a ' as string);
> +------+
> | _c0 |
> +------+
> | 2 |
> +------+
> -- other string expressions preserve trailing space
> select count(*) from ax where t = concat('a', ' ');
> +------+
> | _c0 |
> +------+
> | 0 |
> +------+
> -- varchar col preserves trailing space
> create table stringv as select cast('a ' as varchar(50));
> select count(*) from ax, stringv where t = `_c0`;
> +------+
> | _c0 |
> +------+
> | 0 |
> +------+
> -- string col preserves trailing space
> create table stringa as select 'a ';
> select count(*) from ax, stringa where t = `_c0`;
> +------+
> | _c0 |
> +------+
> | 0 |
> +------+
> {noformat}
> [~jcamachorodriguez] [~kgyrtkirk]
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