Unique constraint on non nullable fields still act like a unique index
(because there is no null value) but internally they are backed by non
unique indexes with uniqueWhenNotNull attribute.
anurag
Mike Matrigali wrote:
I thought from functional spec and ongoing discussion that behavior of
unique constraint on non-nullable columns would be unchanged. So this
constraint should still be backed by a unique index.
Anurag Shekhar (JIRA) wrote:
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https://issues.apache.org/jira/browse/DERBY-3330?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12573032#action_12573032
]
Anurag Shekhar commented on DERBY-3330:
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dml019 test group by clause of unique constraint. When unique
constraint was backed by unique index, distinct scan was used but
after making it non unique constraint this was not the case so the
results are not ordered.
I have checked the test suite from nist web site and it mandates only
number of rows and not their sequence.
provide support for unique constraint over nullable columns
-----------------------------------------------------------
Key: DERBY-3330
URL: https://issues.apache.org/jira/browse/DERBY-3330
Project: Derby
Issue Type: New Feature
Components: Store
Affects Versions: 10.4.0.0
Environment: all
Reporter: Anurag Shekhar
Assignee: Anurag Shekhar
Attachments: BTreeController.diff, derby-3330-testcase.diff,
derby-3330.diff, derby-3330v2.diff, derby-3330v3.diff,
derby-3330v4.diff, derby-3330v5.diff, derby-3330v6.diff,
derby-3330v7.diff, derby-3330v8.diff, derby-3330v9.diff,
FunctionalSpec_DERBY-3330-V2.html, FunctionalSpec_DERBY-3330.html,
UniqueConstraint_Implementation.html,
UniqueConstraint_Implementation_V2.html,
UniqueConstraint_Implementation_V3.html
Allow unique constraint over nullable field. Right now derby support
unique constraint only over not null columns.
