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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-481-16-aa-dropFunction.diff
Attaching derby-481-16-aa-dropFunction.diff. Running tests now. This patch
prevents you from dropping a function mentioned in a generation clause, per the
spec.
The patch builds on the fact that generation clauses are implemented as a kind
of default. Defaults, in turn, are a persistent object for which we already
have good support in our dependency subsystem.
Touches the following files:
M java/engine/org/apache/derby/impl/sql/execute/ColumnInfo.java
Adds dependency information to this driving data structure.
M
java/engine/org/apache/derby/impl/sql/execute/CreateTableConstantAction.java
M
java/engine/org/apache/derby/impl/sql/execute/AlterTableConstantAction.java
M java/engine/org/apache/derby/impl/sql/compile/TableElementList.java
Adds bind-time logic to fill the ColumnInfo with the dependencies of generated
columns. These dependencies were already being identified but the information
was being thrown on the floor.
M java/engine/org/apache/derby/impl/sql/execute/DDLConstantAction.java
M java/engine/org/apache/derby/impl/sql/compile/AlterTableNode.java
M java/engine/org/apache/derby/impl/sql/compile/CreateViewNode.java
Adds execution-time logic to hammer the dependencies into SYS.SYSDEPENDS. The
enforcement of the dependencies is handled by existing machinery in the
dependency subsystem.
M
java/testing/org/apache/derbyTesting/functionTests/tests/lang/GeneratedColumnsTest.java
Adds test cases.
> 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,
> derby-481-12-aa-padding.diff, derby-481-13-aa-alterDatatype.diff,
> derby-481-14-ab-dropColumn.diff, derby-481-15-aa-renameAndAddDefault.diff,
> derby-481-16-aa-dropFunction.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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