Flip IgnoreTransactions default from 0 to 1 for multi-statement transaction preview (#1176)

## Summary
- Changes default value of `IgnoreTransactions` parameter from `0` to
`1`, making transactions disabled by default
- Updates `supportsTransactions()` to respect the `IgnoreTransactions`
flag, returning `false` when transactions are ignored (default) and
`true` when explicitly enabled
- Adds test case for when transactions are explicitly enabled via
`IgnoreTransactions=0`

## Background
The multi-statement transaction feature is currently in private preview
for limited workspaces. When BI tools (Tableau, Power BI, DBeaver)
detect transaction support via `supportsTransactions()`, they
automatically use transaction methods, causing failures for customers
not enrolled in the preview.

This change prevents unexpected failures for non-preview customers while
allowing preview participants to opt-in by explicitly setting
`IgnoreTransactions=0` in their connection string.

## Migration Path
- **Non-preview customers**: No action required - transactions are now
disabled by default
- **Preview participants**: Set `IgnoreTransactions=0` in connection
string to enable transaction support
- **GA migration**: When multi-statement transactions reach GA, flip the
default back to `0`

## Test plan
- [ ] Verify existing tests pass
- [ ] Verify default connection returns `supportsTransactions() = false`
- [ ] Verify connection with `IgnoreTransactions=0` returns
`supportsTransactions() = true`
- [ ] Verify transaction methods (`setAutoCommit`, `commit`, `rollback`)
are no-ops by default

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Signed-off-by: Vikrant Puppala <vikrant.puppala@databricks.com>
Co-authored-by: Claude Opus 4.5 <noreply@anthropic.com>

Author: vikrantpuppala

NEXT_CHANGELOG.md

@@ -6,6 +6,7 @@
 - Added token caching for all authentication providers to reduce token endpoint calls.
 
 ### Updated
+- Changed default value of `IgnoreTransactions` from `0` to `1` to disable multi-statement transactions by default. Preview participants can opt-in by setting `IgnoreTransactions=0`. Also updated `supportsTransactions()` to respect this flag.
 
 ### Fixed
 

src/main/java/com/databricks/jdbc/api/impl/DatabricksConnectionContext.java

@@ -1164,7 +1164,7 @@ public boolean isBatchedInsertsEnabled() {
 
   @Override
   public boolean getIgnoreTransactions() {
-    return getParameter(DatabricksJdbcUrlParams.IGNORE_TRANSACTIONS, "0").equals("1");
+    return getParameter(DatabricksJdbcUrlParams.IGNORE_TRANSACTIONS).equals("1");
   }
 
   @Override

src/main/java/com/databricks/jdbc/api/impl/DatabricksDatabaseMetaData.java

@@ -834,7 +834,7 @@ public int getDefaultTransactionIsolation() throws SQLException {
   public boolean supportsTransactions() throws SQLException {
     LOGGER.debug("public boolean supportsTransactions()");
     throwExceptionIfConnectionIsClosed();
-    return true;
+    return !session.getConnectionContext().getIgnoreTransactions();
   }
 
   @Override

src/main/java/com/databricks/jdbc/common/DatabricksJdbcUrlParams.java

@@ -169,7 +169,7 @@ public enum DatabricksJdbcUrlParams {
       "EnableSQLValidationForIsValid",
       "Enable SQL query execution for connection validation in isValid() method",
       "0"),
-  IGNORE_TRANSACTIONS("IgnoreTransactions", "Ignore transaction-related method calls", "0"),
+  IGNORE_TRANSACTIONS("IgnoreTransactions", "Ignore transaction-related method calls", "1"),
   FETCH_AUTOCOMMIT_FROM_SERVER(
       "FetchAutoCommitFromServer",
       "Fetch auto-commit state from server using SQL query instead of using cached value",

src/test/java/com/databricks/jdbc/api/impl/DatabricksConnectionTest.java

@@ -61,6 +61,10 @@ public class DatabricksConnectionTest {
               .collect(Collectors.joining(";")));
   private static final String IGNORE_TRANSACTIONS_JDBC_URL =
       "jdbc:databricks://sample-host.18.azuredatabricks.net:4423/default;transportMode=http;ssl=1;AuthMech=3;httpPath=/sql/1.0/warehouses/99999999;IgnoreTransactions=1";
+  private static final String TRANSACTIONS_ENABLED_JDBC_URL =
+      String.format(
+          "jdbc:databricks://sample-host.18.azuredatabricks.net:4423/%s;transportMode=http;ssl=1;AuthMech=3;httpPath=/sql/1.0/warehouses/99999999;ConnCatalog=%s;ConnSchema=%s;logLevel=FATAL;IgnoreTransactions=0",
+          SCHEMA, CATALOG, SCHEMA);
   private static final ImmutableSessionInfo IMMUTABLE_SESSION_INFO =
       ImmutableSessionInfo.builder().computeResource(warehouse).sessionId(SESSION_ID).build();
   @Mock DatabricksSdkClient databricksClient;
@@ -69,11 +73,14 @@ public class DatabricksConnectionTest {
   private static DatabricksConnection connection;
 
   private static IDatabricksConnectionContext connectionContext;
+  private static IDatabricksConnectionContext transactionsEnabledContext;
 
   @BeforeAll
   static void setup() throws DatabricksSQLException {
     connectionContext =
         DatabricksConnectionContext.parse(CATALOG_SCHEMA_JDBC_URL, new Properties());
+    transactionsEnabledContext =
+        DatabricksConnectionContext.parse(TRANSACTIONS_ENABLED_JDBC_URL, new Properties());
   }
 
   @Test
@@ -441,9 +448,9 @@ void testUnsupportedOperations() throws SQLException {
               ResultSet.CONCUR_READ_ONLY,
               ResultSet.CLOSE_CURSORS_AT_COMMIT);
         });
-    assertThrows(
-        DatabricksSQLFeatureNotImplementedException.class, () -> connection.setSavepoint("1"));
-    assertThrows(DatabricksSQLFeatureNotImplementedException.class, connection::setSavepoint);
+    // With default IgnoreTransactions=1, savepoint methods return null (no-op)
+    assertNull(connection.setSavepoint("1"));
+    assertNull(connection.setSavepoint());
     assertThrows(DatabricksSQLFeatureNotImplementedException.class, connection::createClob);
     assertThrows(DatabricksSQLFeatureNotImplementedException.class, connection::createBlob);
     assertThrows(DatabricksSQLFeatureNotImplementedException.class, connection::createNClob);
@@ -454,10 +461,9 @@ void testUnsupportedOperations() throws SQLException {
     assertThrows(
         DatabricksSQLFeatureNotSupportedException.class,
         () -> connection.prepareStatement(SQL, new String[0]));
-    assertThrows(
-        DatabricksSQLFeatureNotImplementedException.class, () -> connection.rollback(null));
-    assertThrows(
-        DatabricksSQLFeatureNotImplementedException.class, () -> connection.releaseSavepoint(null));
+    // With default IgnoreTransactions=1, these are no-ops
+    assertDoesNotThrow(() -> connection.rollback(null));
+    assertDoesNotThrow(() -> connection.releaseSavepoint(null));
     assertThrows(
         DatabricksSQLFeatureNotSupportedException.class,
         () -> connection.setNetworkTimeout(null, 1));
@@ -646,7 +652,7 @@ public void testSetAutoCommitToFalse() throws SQLException {
     when(databricksClient.createSession(
             new Warehouse(WAREHOUSE_ID), CATALOG, SCHEMA, new HashMap<>()))
         .thenReturn(IMMUTABLE_SESSION_INFO);
-    connection = new DatabricksConnection(connectionContext, databricksClient);
+    connection = new DatabricksConnection(transactionsEnabledContext, databricksClient);
     connection.open();
 
     DatabricksConnection spyConnection = spy(connection);
@@ -671,7 +677,7 @@ public void testSetAutoCommitToTrue() throws SQLException {
     when(databricksClient.createSession(
             new Warehouse(WAREHOUSE_ID), CATALOG, SCHEMA, new HashMap<>()))
         .thenReturn(IMMUTABLE_SESSION_INFO);
-    connection = new DatabricksConnection(connectionContext, databricksClient);
+    connection = new DatabricksConnection(transactionsEnabledContext, databricksClient);
     connection.open();
 
     DatabricksConnection spyConnection = spy(connection);
@@ -697,7 +703,7 @@ public void testSetAutoCommitWithServerError() throws SQLException {
     when(databricksClient.createSession(
             new Warehouse(WAREHOUSE_ID), CATALOG, SCHEMA, new HashMap<>()))
         .thenReturn(IMMUTABLE_SESSION_INFO);
-    connection = new DatabricksConnection(connectionContext, databricksClient);
+    connection = new DatabricksConnection(transactionsEnabledContext, databricksClient);
     connection.open();
 
     DatabricksConnection spyConnection = spy(connection);
@@ -744,7 +750,7 @@ public void testCommitSuccess() throws SQLException {
     when(databricksClient.createSession(
             new Warehouse(WAREHOUSE_ID), CATALOG, SCHEMA, new HashMap<>()))
         .thenReturn(IMMUTABLE_SESSION_INFO);
-    connection = new DatabricksConnection(connectionContext, databricksClient);
+    connection = new DatabricksConnection(transactionsEnabledContext, databricksClient);
     connection.open();
 
     DatabricksConnection spyConnection = spy(connection);
@@ -785,7 +791,7 @@ public void testCommitWithServerError() throws SQLException {
     when(databricksClient.createSession(
             new Warehouse(WAREHOUSE_ID), CATALOG, SCHEMA, new HashMap<>()))
         .thenReturn(IMMUTABLE_SESSION_INFO);
-    connection = new DatabricksConnection(connectionContext, databricksClient);
+    connection = new DatabricksConnection(transactionsEnabledContext, databricksClient);
     connection.open();
 
     DatabricksConnection spyConnection = spy(connection);
@@ -812,7 +818,7 @@ public void testRollbackSuccess() throws SQLException {
     when(databricksClient.createSession(
             new Warehouse(WAREHOUSE_ID), CATALOG, SCHEMA, new HashMap<>()))
         .thenReturn(IMMUTABLE_SESSION_INFO);
-    connection = new DatabricksConnection(connectionContext, databricksClient);
+    connection = new DatabricksConnection(transactionsEnabledContext, databricksClient);
     connection.open();
 
     DatabricksConnection spyConnection = spy(connection);
@@ -853,7 +859,7 @@ public void testRollbackWithServerError() throws SQLException {
     when(databricksClient.createSession(
             new Warehouse(WAREHOUSE_ID), CATALOG, SCHEMA, new HashMap<>()))
         .thenReturn(IMMUTABLE_SESSION_INFO);
-    connection = new DatabricksConnection(connectionContext, databricksClient);
+    connection = new DatabricksConnection(transactionsEnabledContext, databricksClient);
     connection.open();
 
     DatabricksConnection spyConnection = spy(connection);
@@ -879,7 +885,7 @@ public void testTransactionMethodsPreserveExceptionChain() throws SQLException {
     when(databricksClient.createSession(
             new Warehouse(WAREHOUSE_ID), CATALOG, SCHEMA, new HashMap<>()))
         .thenReturn(IMMUTABLE_SESSION_INFO);
-    connection = new DatabricksConnection(connectionContext, databricksClient);
+    connection = new DatabricksConnection(transactionsEnabledContext, databricksClient);
     connection.open();
 
     DatabricksConnection spyConnection = spy(connection);
@@ -1059,8 +1065,9 @@ public void testSetAutoCommitSkipsServerCallWhenAlreadyFalse() throws SQLExcepti
 
   @Test
   public void testSetAutoCommitDoesNotSkipWithFetchFromServerEnabled() throws SQLException {
-    // Create connection with FetchAutoCommitFromServer=1
-    String urlWithFetch = CATALOG_SCHEMA_JDBC_URL + ";FetchAutoCommitFromServer=1";
+    // Create connection with FetchAutoCommitFromServer=1 and IgnoreTransactions=0
+    String urlWithFetch =
+        CATALOG_SCHEMA_JDBC_URL + ";FetchAutoCommitFromServer=1;IgnoreTransactions=0";
     IDatabricksConnectionContext contextWithFetch =
         DatabricksConnectionContext.parse(urlWithFetch, new Properties());
 

src/test/java/com/databricks/jdbc/api/impl/DatabricksDatabaseMetaDataTest.java

@@ -438,7 +438,20 @@ public void getDefaultTransactionIsolation_returnsExpectedIsolationLevel() throw
   }
 
   @Test
-  public void supportsTransactions_returnsFalse() throws Exception {
+  public void supportsTransactions_returnsFalseByDefault() throws Exception {
+    // Default IgnoreTransactions=1 means transactions are ignored, so supportsTransactions returns
+    // false
+    boolean supportsTransactions = metaData.supportsTransactions();
+    assertFalse(supportsTransactions);
+  }
+
+  @Test
+  public void supportsTransactions_returnsTrueWhenTransactionsEnabled() throws Exception {
+    // When IgnoreTransactions=0, transactions are enabled, so supportsTransactions returns true
+    String urlWithTransactionsEnabled = WAREHOUSE_JDBC_URL + ";IgnoreTransactions=0";
+    when(session.getConnectionContext())
+        .thenReturn(
+            DatabricksConnectionContext.parse(urlWithTransactionsEnabled, new Properties()));
     boolean supportsTransactions = metaData.supportsTransactions();
     assertTrue(supportsTransactions);
   }