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Posted to issues@hive.apache.org by "Peter Vary (Jira)" <ji...@apache.org> on 2020/08/23 08:43:00 UTC
[jira] [Commented] (HIVE-24040) Slightly odd behaviour with CHAR
comparisons and string literals
[ https://issues.apache.org/jira/browse/HIVE-24040?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17182633#comment-17182633 ]
Peter Vary commented on HIVE-24040:
-----------------------------------
[~kuczoram]: You might want to know about this, as I remember you were working to have a standard way to handle this through Parquet and ORC.
> 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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