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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-481-06-aa-genreferences.diff
Attaching derby-481-06-aa-genReferences.diff. This patch makes it illegal for
generated columns to reference other generated columns, per the functional
spec. Running regression tests now.
Touches the following files:
M java/engine/org/apache/derby/impl/sql/compile/ResultColumnList.java
M java/engine/org/apache/derby/iapi/sql/dictionary/TableDescriptor.java
Adds some small helper methods to assist the machinery in
TableElementList.bindAndValidateGenerationClauses.
M java/engine/org/apache/derby/impl/sql/compile/TableElementList.java
Adds logic to raise an exception if a generation clause mentions generated
columns.
M java/engine/org/apache/derby/impl/sql/compile/AlterTableNode.java
M java/engine/org/apache/derby/impl/sql/compile/CreateTableNode.java
Adds new argument to calls to TableElementList.bindAndValidateGenerationClauses.
M java/engine/org/apache/derby/loc/messages.xml
M java/shared/org/apache/derby/shared/common/reference/SQLState.java
Adds new error message raised when generation clauses reference generated
columns.
M
java/testing/org/apache/derbyTesting/functionTests/tests/lang/GeneratedColumnsTest.java
Adds tests for this behavior. While I was in there, I added tests to verify
some other functionality: generation clauses can't reference other tables or
run subqueries.
> 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,
> 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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