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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:
--------------------------------
Attachment: derby-481-03-aa-grammar.diff
Attaching derby-481-03-aa-grammar.diff. I am running regression tests now.
This patch does the following:
1) Makes it possible to declare generated columns in CREATE TABLE statements.
2) Adjusts the dblook tool to emit the correct DDL for tables with generated
columns.
3) Adds some basic syntax tests for CREATE TABLE statements which declare
generated columns.
4) Verifies that you can declare generated columns only after hard-upgrading to
10.5.
I will file new JIRAs to track the following known deficiencies:
A) You cannot add generated columns using ALTER TABLE yet. This behavior can
not be tested until we check in the UPDATE logic for generated columns.
B) The ANSI/ISO grammar lets you omit the column datatype on columns with
generation clauses. The patch does not support this elegant shorthand.
Touches the following files:
----------------
-- PARSING
----------------
M java/engine/org/apache/derby/impl/sql/compile/sqlgrammar.jj
Wires GENERATED ALWAYS AS (...) into the CREATE/ALTER TABLE grammar. This bit
of grammar is known in the SQL spec as a "generation clause".
M java/engine/org/apache/derby/impl/sql/compile/NodeFactoryImpl.java
M java/engine/org/apache/derby/iapi/sql/compile/C_NodeTypes.java
M java/engine/org/apache/derby/impl/sql/compile/C_NodeNames.java
A java/engine/org/apache/derby/impl/sql/compile/GenerationClauseNode.java
M java/engine/org/apache/derby/impl/sql/compile/ColumnDefinitionNode.java
Adds a new kind of Abstract Syntax Tree (AST) node to represent generation
clauses. In the AST, generation clauses decorate column definitions.
----------------
-- BINDING
----------------
M java/engine/org/apache/derby/impl/sql/compile/TableElementList.java
Logic to drive the bind() phase for generation clauses.
M java/engine/org/apache/derby/impl/sql/compile/StaticMethodCallNode.java
M java/engine/org/apache/derby/iapi/sql/compile/CompilerContext.java
M java/engine/org/apache/derby/impl/sql/compile/QueryTreeNode.java
M java/engine/org/apache/derby/impl/sql/compile/ValueNode.java
Bind-time logic to prevent non-deterministic functions from appearing in
generation clauses.
M java/engine/org/apache/derby/impl/sql/compile/AlterTableNode.java
M java/engine/org/apache/derby/impl/sql/compile/DDLStatementNode.java
M java/engine/org/apache/derby/impl/sql/compile/CreateTableNode.java
Factored some very similar bind-time logic out of the AST nodes for CREATE and
ALTER TABLE. Consolidated this logic in the superclass of these two nodes.
----------------
-- TOOLS
----------------
M java/engine/org/apache/derby/catalog/types/DefaultInfoImpl.java
M java/tools/org/apache/derby/impl/tools/dblook/DB_Table.java
Code to make the dblook utility correctly emit generation clauses when printing
CREATE TABLE statements.
----------------
-- TESTS
----------------
M
java/testing/org/apache/derbyTesting/functionTests/tests/lang/GeneratedColumnsTest.java
Uncomments the basic grammar tests. Adds a test to verify that generation
clauses are correctly stored in SYSCOLUMNS.COLUMNDEFAULT.
M
java/testing/org/apache/derbyTesting/functionTests/tests/upgradeTests/Changes10_5.java
Adds a test case to verify that you can declare generation clauses only after
hard-upgrading to 10.5.
M
java/testing/org/apache/derbyTesting/functionTests/tests/tools/dblook_makeDB.sql
M
java/testing/org/apache/derbyTesting/functionTests/master/DerbyNet/dblook_test_net.out
M
java/testing/org/apache/derbyTesting/functionTests/master/DerbyNet/dblook_test_net_territory.out
M
java/testing/org/apache/derbyTesting/functionTests/master/dblook_test_territory.out
M
java/testing/org/apache/derbyTesting/functionTests/master/DerbyNetClient/dblook_test_net.out
M
java/testing/org/apache/derbyTesting/functionTests/master/DerbyNetClient/dblook_test_net_territory.out
M java/testing/org/apache/derbyTesting/functionTests/master/dblook_test.out
Beefs up the dblook test with some examples of CREATE TABLE statements which
have generation clauses.
> 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, 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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