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https://issues.apache.org/jira/browse/DERBY-2280?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12493169
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A B commented on DERBY-2280:
----------------------------
Thanks for the updated patch, Saurabh.
I ran jdbcapi/DatabaseMetaDataTest with a clean codeline and it passed for me.
But as you say, if I run it with your changes applied the test fails when
checking NULLABILITY. The failure occurs because the nullability of the
UNSIGNED_ATTRIBUTE and AUTO_INCREMENT columns becomes "false" with your
changes, wherease it used to be "true".
Without your patch, at least one row in the VALUES clause (actually, two
rows--the row for BLOB and the row for CLOB) has a NULL value for
UNSIGNED_ATTRIBUTE and AUTO_INCREMENT:
('BLOB',2004,2147483647,CAST (NULL AS CHAR),CAST (NULL AS CHAR),'length', \
1,FALSE,0,CAST (NULL AS BOOLEAN),FALSE,CAST (NULL AS BOOLEAN), \
CAST (NULL AS INTEGER),CAST (NULL AS INTEGER),CAST (NULL AS INTEGER)),\
('CLOB',2005,2147483647,'''','''','length', \
1,TRUE,1,CAST (NULL AS BOOLEAN),FALSE,CAST (NULL AS BOOLEAN), \
CAST (NULL AS INTEGER),CAST (NULL AS INTEGER),CAST (NULL AS INTEGER)), \
Since there is at least one row which is null, the type definition for the
corresponding columns implicitly becomes nullable, and thus we see (before your
changes) a NULLABILITY of "true".
But with your patch applied, every row in the VALUES clause used for
getTypeInfo() returns a constant value (TRUE or FALSE) for UNSIGNED_ATTRIBUTE
and AUTO_INCREMENT:
('BLOB',2004,2147483647,CAST (NULL AS CHAR),CAST (NULL AS
CHAR),'length', \
- 1,FALSE,0,CAST (NULL AS BOOLEAN),FALSE,CAST (NULL AS BOOLEAN), \
+ 1,FALSE,0,TRUE,FALSE,FALSE, \
CAST (NULL AS INTEGER),CAST (NULL AS INTEGER),CAST (NULL AS
INTEGER)),\
('CLOB',2005,2147483647,'''','''','length', \
- 1,TRUE,1,CAST (NULL AS BOOLEAN),FALSE,CAST (NULL AS BOOLEAN), \
+ 1,TRUE,1,TRUE,FALSE,FALSE, \
CAST (NULL AS INTEGER),CAST (NULL AS INTEGER),CAST (NULL AS
INTEGER)), \
A constant value that is not null implicitly has a type definition that is not
nullable. So since _all_ rows now have a constant value for the
UNSIGNED_ATTRIBUTE and AUTO_INCREMENT columns, the type definitions for those
two columns become "not nullable", which translates into a "false" NULLABILITY.
Hence the failure in DatabaseMetaDataTest.
This difference in behavior is, I think, related to the discussion for
DERBY-2307. That issue talks about how the derived nullability of a column for
getTypeInfo() is correct for some columns (ex. DATA_TYPE) but incorrect for
others (ex. TYPE_NAME). The difference is that all columns which use an
explict CAST operand assume a nullability of "true", while a column that has
all constants with no CASTs assumes a nullability of "false".
That said, it's not clear to me what the nullability of the AUTO_INCREMENT and
UNSIGNED_ATTRIBUTE columns should be. I posted a question to DERBY-2307; we'll
have to figure that out before we know how to handle the DatabaseMetaDataTest
failure that you are seeing with your patch...
Minor comment on the _v2 patch:
Spacing for the changes to DatabaseMetaDataTest.java are inconsistent. Some of
the new code uses tabs whereas other pieces use spaces. Since the surrounding
(unchanged) code uses 4-space indentation, I think it'd be best to use that for
the new code, as well...
> DatabaseMetaData.getTypeInfo() UNSIGNED_ATTRIBUTE and AUTO_INCREMENT column
> returns incorrect information for BLOB & CLOB data type
> -----------------------------------------------------------------------------------------------------------------------------------
>
> Key: DERBY-2280
> URL: https://issues.apache.org/jira/browse/DERBY-2280
> Project: Derby
> Issue Type: Bug
> Components: JDBC
> Affects Versions: 10.0.2.1, 10.1.1.0, 10.1.2.1, 10.1.3.1, 10.2.1.6,
> 10.2.2.0, 10.3.0.0
> Reporter: Saurabh Vyas
> Assigned To: Saurabh Vyas
> Priority: Minor
> Attachments: Derby-2280.diff, Derby-2280.stat, Derby-2280_v2.diff
>
>
> getTypeInfo() method should return FALSE for UNSIGNED_ATTRIBUTE and
> AUTO_INCREMENT in case of BLOB & CLOB data type.
> Currently it returns NULL value.
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