fix(redshift): adding distKey to an existing table fails deployment (#…

…26789)

The current implementation executes a `CREATE TABLE` if the table has no `distKey` specified and one is added, or if a `distKey` is present and is removed.
The resulting table is created with the same name, causing the update operation to fail.
This fixes the problem by using [`ALTER TABLE`](https://docs.aws.amazon.com/redshift/latest/dg/r_ALTER_TABLE.html) when adding/removing `distKey` on a table update. 

Closes #26733.

----

*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-alpha/lib/private/database-query-provider/table.ts

@@ -164,9 +164,14 @@ async function updateTable(
 
   const oldDistKey = getDistKeyColumn(oldTableColumns)?.name;
   const newDistKey = getDistKeyColumn(tableColumns)?.name;
-  if ((!oldDistKey && newDistKey ) || (oldDistKey && !newDistKey)) {
-    return createTable(tableNamePrefix, tableNameSuffix, tableColumns, tableAndClusterProps);
+  if (!oldDistKey && newDistKey) {
+    // Table has no existing distribution key, add a new one
+    alterationStatements.push(`ALTER TABLE ${tableName} ALTER DISTSTYLE KEY DISTKEY ${newDistKey}`);
+  } else if (oldDistKey && !newDistKey) {
+    // Table has a distribution key, remove and set to AUTO
+    alterationStatements.push(`ALTER TABLE ${tableName} ALTER DISTSTYLE AUTO`);
   } else if (oldDistKey !== newDistKey) {
+    // Table has an existing distribution key, change it
     alterationStatements.push(`ALTER TABLE ${tableName} ALTER DISTKEY ${newDistKey}`);
   }
 

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

@@ -384,21 +384,21 @@ describe('update', () => {
       }));
     });
 
-    test('replaces if distKey is added', async () => {
+    test('adds key without creating table if distKey is added', async () => {
       const newResourceProperties: ResourcePropertiesType = {
         ...resourceProperties,
         tableColumns: [{ name: 'col1', dataType: 'varchar(1)', distKey: true }],
       };
 
-      await expect(manageTable(newResourceProperties, event)).resolves.not.toMatchObject({
+      await expect(manageTable(newResourceProperties, event)).resolves.toMatchObject({
         PhysicalResourceId: physicalResourceId,
       });
       expect(mockExecuteStatement).toHaveBeenCalledWith(expect.objectContaining({
-        Sql: `CREATE TABLE ${tableNamePrefix}${requestIdTruncated} (col1 varchar(1)) DISTKEY(col1)`,
+        Sql: `ALTER TABLE ${physicalResourceId} ALTER DISTSTYLE KEY DISTKEY col1`,
       }));
     });
 
-    test('replaces if distKey is removed', async () => {
+    test('removes key without replacing table if distKey is removed', async () => {
       const newEvent: AWSLambda.CloudFormationCustomResourceEvent = {
         ...event,
         OldResourceProperties: {
@@ -410,11 +410,11 @@ describe('update', () => {
         ...resourceProperties,
       };
 
-      await expect(manageTable(newResourceProperties, newEvent)).resolves.not.toMatchObject({
+      await expect(manageTable(newResourceProperties, newEvent)).resolves.toMatchObject({
         PhysicalResourceId: physicalResourceId,
       });
       expect(mockExecuteStatement).toHaveBeenCalledWith(expect.objectContaining({
-        Sql: `CREATE TABLE ${tableNamePrefix}${requestIdTruncated} (col1 varchar(1))`,
+        Sql: `ALTER TABLE ${physicalResourceId} ALTER DISTSTYLE AUTO`,
       }));
     });