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https://issues.apache.org/jira/browse/HIVE-9537?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14327408#comment-14327408
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N Campbell commented on HIVE-9537:
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I wouldn't suggest that use MySQL and Postgres alone is ideal to cross check
SQL semantics.
Should the Apache implementation for CHAR(n) stay this way going forward I
recommend you get the documentation improved.
Having seen companies migrate applications across vendors where this sort of
thing burns them. Many may not know what ISO-SQL 20xx states (let alone care)
and will presume that their source vendor(s) have followed the specification
etc.
Given the server side string operations etc, they may as well stay with VARCHAR
and know that trailing spaces are not preserved vs the 'appears' to have spaces
when projected but not in other cases.
See discussion:
http://www.postgresql.org/docs/9.1/static/datatype-character.html
See discussion of MySQL JDBC:
https://dev.mysql.com/doc/connector-j/en/connector-j-reference-configuration-properties.html
re padCharsWithSpace
If you apply a <fold> (upper/lower) the type of the result is supposed to be
from the <character value expression>
Length should be the number of characters in the <string value expression> -
where number of characters is based upon the semantics of the character set of
the <string value expression>
If both operands are fixed length character strings, concatenation result is a
fixed length character string with a length equal to the sum of the lengths of
the operands where the length cannot exceed the maximum allowed for a fixed
length character string.
Cheers.
> string expressions on a fixed length character do not preserve trailing spaces
> ------------------------------------------------------------------------------
>
> Key: HIVE-9537
> URL: https://issues.apache.org/jira/browse/HIVE-9537
> Project: Hive
> Issue Type: Bug
> Components: SQL
> Reporter: N Campbell
> Assignee: Aihua Xu
>
> When a string expression such as upper or lower is applied to a fixed length
> column the trailing spaces of the fixed length character are not preserved.
> {code:sql}
> CREATE TABLE if not exists TCHAR (
> RNUM int,
> CCHAR char(32)
> )
> ROW FORMAT DELIMITED
> FIELDS TERMINATED BY '|'
> LINES TERMINATED BY '\n'
> STORED AS TEXTFILE;
> {code}
> {{cchar}} as a {{char(32)}}.
> {code:sql}
> select cchar, concat(cchar, cchar), concat(lower(cchar), cchar),
> concat(upper(cchar), cchar)
> from tchar;
> {code}
> 0|\N
> 1|
> 2|
> 3|BB
> 4|EE
> 5|FF
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