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From "Rick Hillegas (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (DERBY-5235) Remove the artificial limit on the length of VARCHAR values, allowing them to be java.lang.Integer.MAX_VALUE long
Date Thu, 19 May 2011 14:56:47 GMT

    [ https://issues.apache.org/jira/browse/DERBY-5235?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13036238#comment-13036238
] 

Rick Hillegas commented on DERBY-5235:
--------------------------------------

Here's what our standards have to say about long Strings:

According to the 2008 SQL Standard, part 2, section 4.2.1 (Introduction to Character Strings),
cf. section 6.1 (<data type>):

i) The standard String types are CHAR, VARCHAR, CLOB, NCHAR, NVARCHAR, and NCLOB.

According to section 4.2.3.4:

ii)  The =, <>, and NOT NULL operators must work on CLOB. However, the other comparison
operators are not supported: >, <, >=, <=.

iii) Other supported operations are LIKE, SIMILAR, EXISTS, SOME, ANY, and positioning expressions.

iv) CLOBs are not supported in unique and referential constraints, or in GROUP BY, ORDER BY,
DISTINCT, UNION, INTERSECT, and EXCEPT expressions, or in the join conditions of joined tables.

LONG VARCHAR is not a Standard SQL type and so the Standard provides no guidance for its behavior.
However, a java.sql.LONGVARCHAR type was introduced in JDBC 1.0. It differs from java.sql.CHAR
and java.sql.VARCHAR in that its preferred access methods are character streams rather than
Strings. The actual java.sql.CLOB type was not introduced until JDBC 2.0.


> Remove the artificial limit on the length of VARCHAR values, allowing them to be java.lang.Integer.MAX_VALUE
long
> -----------------------------------------------------------------------------------------------------------------
>
>                 Key: DERBY-5235
>                 URL: https://issues.apache.org/jira/browse/DERBY-5235
>             Project: Derby
>          Issue Type: Improvement
>          Components: SQL
>    Affects Versions: 10.9.0.0
>            Reporter: Rick Hillegas
>
> The original Cloudscape limit for the length of VARCHAR values was java.lang.Integer.MAX_VALUE.
That is the limit in Cloudscape 5.1. Nothing in Derby should break if we restore the original
limit. The current limit is an artificial bound introduced to make Derby agree with DB2. 32672
is the upper bound on the length of a DB2 VARCHAR: http://publib.boulder.ibm.com/infocenter/db2luw/v8/index.jsp?topic=/com.ibm.db2.udb.doc/admin/r0001029.htm

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