feat(redshift): columns require an id attribute (under feature flag) (a…

…ws#24272)

Adds an `id` attribute to retain tables on changing of the column name. This will essentially fire an `ALTER` statement to rename the column, whilst persisting the id, so columns cannot be dropped.

Closes aws#24234.

----

*By submitting this pull request, I confirm that my contribution is made under the terms of the Apache-2.0 license*

packages/@aws-cdk/aws-redshift/README.md

@@ -214,6 +214,21 @@ new Table(this, 'Table', {
 });
 ```
 
+Table columns can also contain an `id` attribute, which can allow table columns to be renamed.
+
+**NOTE** To use the `id` attribute, you must also enable the `@aws-cdk/aws-redshift:columnId` feature flag.
+
+```ts fixture=cluster
+new Table(this, 'Table', {
+  tableColumns: [
+    { id: 'col1', name: 'col1', dataType: 'varchar(4)' }, 
+    { id: 'col2', name: 'col2', dataType: 'float' }
+  ],
+  cluster: cluster,
+  databaseName: 'databaseName',
+});
+```
+
 ### Granting Privileges
 
 You can give a user privileges to perform certain actions on a table by using the

packages/@aws-cdk/aws-redshift/lib/private/database-query-provider/table.ts

@@ -10,6 +10,7 @@ export async function handler(props: TableAndClusterProps, event: AWSLambda.Clou
   const tableNameSuffix = props.tableName.generateSuffix === 'true' ? `${event.RequestId.substring(0, 8)}` : '';
   const tableColumns = props.tableColumns;
   const tableAndClusterProps = props;
+  const useColumnIds = props.useColumnIds;
 
   if (event.RequestType === 'Create') {
     const tableName = await createTable(tableNamePrefix, tableNameSuffix, tableColumns, tableAndClusterProps);
@@ -23,6 +24,7 @@ export async function handler(props: TableAndClusterProps, event: AWSLambda.Clou
       tableNamePrefix,
       tableNameSuffix,
       tableColumns,
+      useColumnIds,
       tableAndClusterProps,
       event.OldResourceProperties as TableAndClusterProps,
     );
@@ -77,6 +79,7 @@ async function updateTable(
   tableNamePrefix: string,
   tableNameSuffix: string,
   tableColumns: Column[],
+  useColumnIds: boolean,
   tableAndClusterProps: TableAndClusterProps,
   oldResourceProperties: TableAndClusterProps,
 ): Promise<string> {
@@ -94,19 +97,44 @@ async function updateTable(
 
   const oldTableColumns = oldResourceProperties.tableColumns;
   const columnDeletions = oldTableColumns.filter(oldColumn => (
-    tableColumns.every(column => oldColumn.name !== column.name)
+    tableColumns.every(column => {
+      if (useColumnIds) {
+        return oldColumn.id ? oldColumn.id !== column.id : oldColumn.name !== column.name;
+      }
+      return oldColumn.name !== column.name;
+    })
   ));
   if (columnDeletions.length > 0) {
     alterationStatements.push(...columnDeletions.map(column => `ALTER TABLE ${tableName} DROP COLUMN ${column.name}`));
   }
 
   const columnAdditions = tableColumns.filter(column => {
-    return !oldTableColumns.some(oldColumn => column.name === oldColumn.name && column.dataType === oldColumn.dataType);
+    return !oldTableColumns.some(oldColumn => {
+      if (useColumnIds) {
+        return oldColumn.id ? oldColumn.id === column.id : oldColumn.name === column.name;
+      }
+      return oldColumn.name === column.name;
+    });
   }).map(column => `ADD ${column.name} ${column.dataType}`);
   if (columnAdditions.length > 0) {
     alterationStatements.push(...columnAdditions.map(addition => `ALTER TABLE ${tableName} ${addition}`));
   }
 
+  if (useColumnIds) {
+    const columnNameUpdates = tableColumns.reduce((updates, column) => {
+      const oldColumn = oldTableColumns.find(oldCol => oldCol.id && oldCol.id === column.id);
+      if (oldColumn && oldColumn.name !== column.name) {
+        updates[oldColumn.name] = column.name;
+      }
+      return updates;
+    }, {} as Record<string, string>);
+    if (Object.keys(columnNameUpdates).length > 0) {
+      alterationStatements.push(...Object.entries(columnNameUpdates).map(([oldName, newName]) => (
+        `ALTER TABLE ${tableName} RENAME COLUMN ${oldName} TO ${newName}`
+      )));
+    }
+  }
+
   const oldDistStyle = oldResourceProperties.distStyle;
   if ((!oldDistStyle && tableAndClusterProps.distStyle) ||
     (oldDistStyle && !tableAndClusterProps.distStyle)) {

packages/@aws-cdk/aws-redshift/lib/private/handler-props.ts

@@ -21,6 +21,7 @@ export interface TableHandlerProps {
   readonly distStyle?: TableDistStyle;
   readonly sortStyle: TableSortStyle;
   readonly tableComment?: string;
+  readonly useColumnIds: boolean;
 }
 
 export interface TablePrivilege {

packages/@aws-cdk/aws-redshift/lib/table.ts

@@ -1,4 +1,6 @@
+/* eslint-disable import/no-extraneous-dependencies */
 import * as cdk from '@aws-cdk/core';
+import { REDSHIFT_COLUMN_ID } from '@aws-cdk/cx-api';
 import { Construct, IConstruct } from 'constructs';
 import { ICluster } from './cluster';
 import { DatabaseOptions } from './database-options';
@@ -55,9 +57,18 @@ export enum TableAction {
  */
 export interface Column {
   /**
-   * The unique name/identifier of the column.
+   * The unique identifier of the column.
    *
-   * **NOTE**. After deploying this column, you cannot change its name. Doing so will cause the column to be dropped and recreated.
+   * This is not the name of the column, and renaming this identifier will cause a new column to be created and the old column to be dropped.
+   *
+   * **NOTE** - This field will be set, however, only by setting the `@aws-cdk/aws-redshift:columnId` feature flag will this field be used.
+   *
+   * @default - the column name is used as the identifier
+   */
+  readonly id?: string;
+
+  /**
+   * The name of the column. This will appear on Amazon Redshift.
    */
   readonly name: string;
 
@@ -217,6 +228,7 @@ export class Table extends TableBase {
   constructor(scope: Construct, id: string, props: TableProps) {
     super(scope, id);
 
+    this.addColumnIds(props.tableColumns);
     this.validateDistKeyColumns(props.tableColumns);
     if (props.distStyle) {
       this.validateDistStyle(props.distStyle, props.tableColumns);
@@ -229,6 +241,8 @@ export class Table extends TableBase {
     this.cluster = props.cluster;
     this.databaseName = props.databaseName;
 
+    const useColumnIds = !!cdk.FeatureFlags.of(this).isEnabled(REDSHIFT_COLUMN_ID);
+
     this.resource = new DatabaseQuery<TableHandlerProps>(this, 'Resource', {
       removalPolicy: cdk.RemovalPolicy.RETAIN,
       ...props,
@@ -242,6 +256,7 @@ export class Table extends TableBase {
         distStyle: props.distStyle,
         sortStyle: props.sortStyle ?? this.getDefaultSortStyle(props.tableColumns),
         tableComment: props.tableComment,
+        useColumnIds,
       },
     });
 
@@ -297,6 +312,18 @@ export class Table extends TableBase {
     const sortKeyColumns = getSortKeyColumns(columns);
     return (sortKeyColumns.length === 0) ? TableSortStyle.AUTO : TableSortStyle.COMPOUND;
   }
+
+  private addColumnIds(columns: Column[]): void {
+    const columnIds = new Set<string>();
+    for (const column of columns) {
+      if (column.id) {
+        if (columnIds.has(column.id)) {
+          throw new Error(`Column id '${column.id}' is not unique.`);
+        }
+        columnIds.add(column.id);
+      }
+    }
+  }
 }
 
 /**

packages/@aws-cdk/aws-redshift/test/database-query-provider/table.test.ts

@@ -19,6 +19,7 @@ const adminUserArn = 'adminUserArn';
 const databaseName = 'databaseName';
 const physicalResourceId = 'PhysicalResourceId';
 const resourceProperties: ResourcePropertiesType = {
+  useColumnIds: true,
   tableName: {
     prefix: tableNamePrefix,
     generateSuffix: 'true',
@@ -270,6 +271,59 @@ describe('update', () => {
     }));
   });
 
+  describe('column name', () => {
+    test('does not replace if column name changed', async () => {
+      const newEvent = {
+        ...event,
+        OldResourceProperties: {
+          ...event.OldResourceProperties,
+          tableColumns: [
+            { id: 'col1', name: 'col1', dataType: 'varchar(1)' },
+          ],
+        },
+      };
+      const newTableColumnName = 'col2';
+      const newResourceProperties: ResourcePropertiesType = {
+        ...resourceProperties,
+        tableColumns: [
+          { id: 'col1', name: newTableColumnName, dataType: 'varchar(1)' },
+        ],
+      };
+
+      await expect(manageTable(newResourceProperties, newEvent)).resolves.toMatchObject({
+        PhysicalResourceId: physicalResourceId,
+      });
+      expect(mockExecuteStatement).toHaveBeenCalledWith(expect.objectContaining({
+        Sql: `ALTER TABLE ${physicalResourceId} RENAME COLUMN col1 TO ${newTableColumnName}`,
+      }));
+    });
+
+    test('does not replace if column id assigned, from undefined', async () => {
+      const newEvent = {
+        ...event,
+        OldResourceProperties: {
+          ...event.OldResourceProperties,
+          tableColumns: [
+            { name: 'col1', dataType: 'varchar(1)' },
+          ],
+        },
+      };
+      const newResourceProperties: ResourcePropertiesType = {
+        ...resourceProperties,
+        tableColumns: [
+          { id: 'col1', name: 'col1', dataType: 'varchar(1)' },
+        ],
+      };
+
+      await expect(manageTable(newResourceProperties, newEvent)).resolves.toMatchObject({
+        PhysicalResourceId: physicalResourceId,
+      });
+      expect(mockExecuteStatement).not.toHaveBeenCalledWith(expect.objectContaining({
+        Sql: `ALTER TABLE ${physicalResourceId} RENAME COLUMN col1 TO col1`,
+      }));
+    });
+  });
+
   describe('distStyle and distKey', () => {
     test('replaces if distStyle is added', async () => {
       const newResourceProperties: ResourcePropertiesType = {