Deprecate EnableArrow flag — Arrow always enabled except on AIX/IBM Power

EnableArrow=0 is now ignored on non-AIX platforms. Arrow serialization
is always enabled. A deprecation warning is logged when EnableArrow=0
is explicitly set.

For JSON inline results with SEA, use EnableQueryResultDownload=0
instead. On AIX (os.name=AIX) or IBM Power (os.arch contains ppc),
the flag is still honoured due to Arrow native library issues.

Removed the client-type check that forced Thrift when Arrow was
disabled — no longer needed since Arrow is always on.

Co-authored-by: Isaac
Signed-off-by: Gopal Lal <gopal.lal@databricks.com>

Author: gopalldb

NEXT_CHANGELOG.md

@@ -12,6 +12,8 @@
 
 4. **Native geospatial type support (`GEOMETRY` and `GEOGRAPHY`) is now enabled by default.** `getObject()` now returns `IGeometry`/`IGeography` instances instead of EWKT strings. Set `EnableGeoSpatialSupport=0` to restore the previous behavior.
 
+5. **`EnableArrow` connection property is deprecated and ignored.** Arrow serialization is now always enabled. Setting `EnableArrow=0` previously disabled Arrow and forced columnar/JSON inline results; this value is now ignored and a deprecation warning is logged. For JSON inline results with SEA, disable CloudFetch via `EnableQueryResultDownload=0`. The only exception is AIX platforms, where `EnableArrow` is still honoured due to known Arrow native library compatibility issues.
+
 ### Added
 
 ### Updated

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

@@ -505,10 +505,6 @@ public DatabricksClientType getClientTypeFromContext() {
           remainingMs);
       return DatabricksClientType.THRIFT;
     }
-    // Check if Arrow is disabled - Thrift is required for inline mode
-    if (!Objects.equals(getParameter(DatabricksJdbcUrlParams.ENABLE_ARROW), "1")) {
-      return DatabricksClientType.THRIFT;
-    }
     // Check if CloudFetch is disabled - Thrift is required for inline mode
     if (!isCloudFetchEnabled()) {
       return DatabricksClientType.THRIFT;
@@ -669,7 +665,26 @@ public ProxyConfig.ProxyAuthType getCloudFetchProxyAuthType() {
 
   @Override
   public Boolean shouldEnableArrow() {
-    return Objects.equals(getParameter(DatabricksJdbcUrlParams.ENABLE_ARROW), "1");
+    // Arrow is always enabled unless running on AIX or IBM Power (which have known
+    // issues with the Arrow native library). The EnableArrow connection property is
+    // deprecated and its value is ignored on non-AIX/IBM platforms.
+    String osName = System.getProperty("os.name", "").toLowerCase();
+    String osArch = System.getProperty("os.arch", "").toLowerCase();
+    if (osName.contains("aix") || osArch.contains("ppc")) {
+      // On AIX/IBM Power, honour the user's explicit setting (default is "1" = enabled)
+      return Objects.equals(getParameter(DatabricksJdbcUrlParams.ENABLE_ARROW), "1");
+    }
+
+    // Log deprecation warning if user explicitly set EnableArrow=0 (ignored)
+    String explicitValue = getParameterIgnoreDefault(DatabricksJdbcUrlParams.ENABLE_ARROW);
+    if (explicitValue != null && explicitValue.equals("0")) {
+      LOGGER.warn(
+          "EnableArrow=0 is deprecated and ignored. Arrow serialization is always enabled. "
+              + "To use JSON inline results with SEA, disable CloudFetch via "
+              + "EnableQueryResultDownload=0.");
+    }
+
+    return true;
   }
 
   @Override

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

@@ -55,7 +55,11 @@ public enum DatabricksJdbcUrlParams {
   DISCOVERY_URL("OAuthDiscoveryURL", "OAuth discovery URL"), // Same as OIDC_DISCOVERY_ENDPOINT
   IDENTITY_FEDERATION_CLIENT_ID(
       "Identity_Federation_Client_Id", "OAuth Client ID for Token Federation"),
-  ENABLE_ARROW("EnableArrow", "Enable Arrow", "1"),
+  ENABLE_ARROW(
+      "EnableArrow",
+      "Deprecated: Arrow is always enabled. Value ignored except on AIX. "
+          + "Use EnableQueryResultDownload=0 for JSON inline results with SEA.",
+      "1"),
   DIRECT_RESULT("EnableDirectResults", "Enable direct results", "1"),
   LZ4_COMPRESSION_FLAG(
       "EnableQueryResultLZ4Compression", "Enable LZ4 compression"), // Backward compatibility

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

@@ -351,10 +351,11 @@ public void testEnableCloudFetch() throws DatabricksSQLException {
         (DatabricksConnectionContext)
             DatabricksConnectionContext.parse(TestConstants.VALID_URL_5, properties);
     assertTrue(connectionContext.shouldEnableArrow());
+    // EnableArrow=0 is deprecated and ignored on non-AIX platforms — always returns true
     connectionContext =
         (DatabricksConnectionContext)
             DatabricksConnectionContext.parse(TestConstants.VALID_URL_7, properties);
-    assertFalse(connectionContext.shouldEnableArrow());
+    assertTrue(connectionContext.shouldEnableArrow());
   }
 
   @Test
@@ -1104,11 +1105,12 @@ public void testClientTypeWhenFeatureFlagNotFound() throws DatabricksSQLExceptio
     "false, 1, 1, 1, true, THRIFT", // Explicit useThriftClient=1 returns THRIFT
     "false, 0, 1, 1, true, SEA", // Explicit useThriftClient=0 returns SEA
     "false, 0, 1, 1, false, SEA", // Explicit useThriftClient=0 returns SEA (ignores flag)
-    "false, null, 0, 1, true, THRIFT", // Arrow disabled returns THRIFT
+    "false, null, 0, 1, true, SEA", // Arrow param ignored (deprecated) + CloudFetch enabled +
+    // flag=true → SEA
     "false, null, 1, 0, true, THRIFT", // CloudFetch disabled returns THRIFT
     "false, null, 1, 1, true, SEA", // All enabled + flag=true returns SEA
     "false, null, 1, 1, false, THRIFT", // All enabled + flag=false returns THRIFT
-    "false, null, 0, 0, true, THRIFT", // Both Arrow and CloudFetch disabled returns THRIFT
+    "false, null, 0, 0, true, THRIFT", // CloudFetch disabled returns THRIFT (Arrow param ignored)
   })
   public void testClientTypeDecisionMatrix(
       boolean isCluster,