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https://issues.apache.org/jira/browse/DERBY-481?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Rick Hillegas updated DERBY-481:
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Attachment: derby-481-11-aa-notNull.diff
Attaching derby-481-11-aa-notNull.diff. Running tests now. This patch adds
support for NOT NULL constraints on generated columns. Makes the following
changes:
A) Exposes the "normalization" logic in NormalizeResultSet and applies this
logic to generated columns. This logic is what enforces NOT NULL constraints.
This logic was already being called by the INSERT and UPDATE execution-time
logic after populating the target row. Using the terms introduced above with
the summary of patch derby-481-04-aa-insert.diff: the normalization logic was
being called immediately after (1') executed but it wasn't being called after
(2') was executed. Now this logic is also called on generated columns after
they are populated--that is, after (2') runs.
B) Loosens a condition which prevents ALTER TABLE from adding new columns which
don't have DEFAULT clauses. Now it's ok to add these clauses with NOT NULL if
they are generated columns.
C) Adds some tests to verify (A) and (B).
Touches the following files:
M java/engine/org/apache/derby/impl/sql/execute/NormalizeResultSet.java
Exposes the "normalization" logic which is called after (1') runs.
M java/engine/org/apache/derby/impl/sql/GenericColumnDescriptor.java
M java/engine/org/apache/derby/iapi/sql/ResultColumnDescriptor.java
Adds a new method to ResultColumnDescriptors so that they can be asked whether
they represent generated columns. This is useful so that we only call the
normalization logic on generated columns rather than all columns in the target
row.
M java/engine/org/apache/derby/impl/sql/execute/NoRowsResultSetImpl.java
Calls the normalization logic on generated columns just after (2') runs.
Slightly changes the signature of evaluateGenerationClauses().
M java/engine/org/apache/derby/impl/sql/execute/InsertResultSet.java
M java/engine/org/apache/derby/impl/sql/execute/UpdateResultSet.java
Reworks calls to evaluateGenerationClauses().
M java/engine/org/apache/derby/impl/sql/compile/ColumnDefinitionNode.java
Changes the ALTER TABLE logic for (B).
M
java/testing/org/apache/derbyTesting/functionTests/tests/lang/GeneratedColumnsTest.java
Adds new tests.
> implement SQL generated columns
> -------------------------------
>
> Key: DERBY-481
> URL: https://issues.apache.org/jira/browse/DERBY-481
> Project: Derby
> Issue Type: New Feature
> Components: SQL
> Affects Versions: 10.0.2.1
> Reporter: Rick Hillegas
> Assignee: Rick Hillegas
> Attachments: derby-481-00-aa-prototype.diff,
> derby-481-01-aa-catalog.diff, derby-481-02-aa-utilities.diff,
> derby-481-03-aa-grammar.diff, derby-481-04-aa-insert.diff,
> derby-481-05-aa-update.diff, derby-481-06-aa-genreferences.diff,
> derby-481-07-aa-noSQLinRoutines.diff, derby-481-07-ab-noSQLinRoutines.diff,
> derby-481-08-aa-castToDeclaredType.diff, derby-481-09-aa-dummyDefaults.diff,
> derby-481-10-aa-foreignKeyActions.diff, derby-481-11-aa-notNull.diff,
> GeneratedColumns.html
>
>
> Satheesh has pointed out that generated columns, a SQL 2003 feature, would
> satisfy the performance requirements of Expression Indexes (bug 455).
> Generated columns may not be as elegant as Expression Indexes, but they are
> easier to implement. We would allow the following new kind of column
> definition in CREATE TABLE and ALTER TABLE statements:
> columnName GENERATED ALWAYS AS ( expression )
> If expression were an indexableExpression (as defined in bug 455), then we
> could create indexes on it. There is no work for the optimizer to do here.
> The Language merely has to compute the generated column at INSERT/UPDATE time.
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