diff --git a/lib/kernel/KernelSessionBackend.ts b/lib/kernel/KernelSessionBackend.ts
index 6cbc745e..685f5b8c 100644
--- a/lib/kernel/KernelSessionBackend.ts
+++ b/lib/kernel/KernelSessionBackend.ts
@@ -393,19 +393,8 @@ export default class KernelSessionBackend implements ISessionBackend {
 
   public async getPrimaryKeys(request: PrimaryKeysRequest): Promise<IOperationBackend> {
     this.failIfClosed();
-    // The kernel requires a catalog for primary-key lookup (`Identifier::new`
-    // rejects an empty string). The Thrift backend can forward an undefined
-    // catalog and let the server resolve a default; the kernel path cannot,
-    // so reject up front with a clear, actionable message rather than passing
-    // `''` and surfacing the kernel's opaque "identifier must not be empty".
-    if (request.catalogName === undefined || request.catalogName === '') {
-      throw new HiveDriverError(
-        'kernel getPrimaryKeys requires a catalog — pass `catalogName` explicitly. (The Thrift backend ' +
-          'can omit it and let the server resolve a default; the kernel kernel path requires it.)',
-      );
-    }
     return this.runMetadata(() =>
-      this.connection.getPrimaryKeys(request.catalogName as string, request.schemaName, request.tableName),
+      this.connection.getPrimaryKeys(request.catalogName, request.schemaName, request.tableName),
     );
   }
 
diff --git a/native/kernel/index.d.ts b/native/kernel/index.d.ts
index 51644c72..206f792c 100644
--- a/native/kernel/index.d.ts
+++ b/native/kernel/index.d.ts
@@ -403,7 +403,7 @@ export declare class Connection {
    * Primary keys for the given table. All three identifiers are
    * exact — ODBC `SQLPrimaryKeys` does not support patterns.
    */
-  getPrimaryKeys(catalog: string, schema: string, table: string): Promise<Statement>
+  getPrimaryKeys(catalog: string | undefined | null, schema: string | undefined | null, table: string): Promise<Statement>
   /**
    * Foreign-key relationships. The foreign side must be fully
    * specified (catalog + schema + table); the parent side is
diff --git a/tests/unit/DBSQLSession.test.ts b/tests/unit/DBSQLSession.test.ts
index 59c19813..11f6142f 100644
--- a/tests/unit/DBSQLSession.test.ts
+++ b/tests/unit/DBSQLSession.test.ts
@@ -5,6 +5,7 @@ import DBSQLSession, { numberToInt64 } from '../../lib/DBSQLSession';
 import InfoValue from '../../lib/dto/InfoValue';
 import Status from '../../lib/dto/Status';
 import DBSQLOperation from '../../lib/DBSQLOperation';
+import { PrimaryKeysRequest } from '../../lib/contracts/IDBSQLSession';
 import ISessionBackend from '../../lib/contracts/ISessionBackend';
 import ParameterError from '../../lib/errors/ParameterError';
 import { TSessionHandle, TProtocolVersion } from '../../thrift/TCLIService_types';
@@ -514,6 +515,25 @@ describe('DBSQLSession', () => {
   });
 
   describe('getPrimaryKeys', () => {
+    it('should forward null, omitted, and empty namespace names unchanged for Thrift', async () => {
+      for (const catalogName of [undefined, null, '', 'catalog']) {
+        for (const schemaName of [undefined, null, '', 'schema']) {
+          const context = new ClientContextStub();
+          const session = createSessionForTest({ handle: sessionHandleStub, context });
+          // eslint-disable-next-line no-await-in-loop
+          const result = await session.getPrimaryKeys({
+            catalogName,
+            schemaName,
+            tableName: 't1',
+          } as PrimaryKeysRequest);
+          expect(result).instanceOf(DBSQLOperation);
+          expect(context.driver.getPrimaryKeysReq?.catalogName).to.equal(catalogName);
+          expect(context.driver.getPrimaryKeysReq?.schemaName).to.equal(schemaName);
+          expect(context.driver.getPrimaryKeysReq?.tableName).to.equal('t1');
+        }
+      }
+    });
+
     it('should run operation', async () => {
       const session = createSessionForTest({ handle: sessionHandleStub, context: new ClientContextStub() });
       const result = await session.getPrimaryKeys({
diff --git a/tests/unit/kernel/execution.test.ts b/tests/unit/kernel/execution.test.ts
index af7d53c3..e1d35f4f 100644
--- a/tests/unit/kernel/execution.test.ts
+++ b/tests/unit/kernel/execution.test.ts
@@ -21,6 +21,7 @@ import KernelSessionBackend from '../../../lib/kernel/KernelSessionBackend';
 import KernelOperationBackend from '../../../lib/kernel/KernelOperationBackend';
 import { KernelNativeBinding, KernelConnection, KernelStatement } from '../../../lib/kernel/KernelNativeLoader';
 import IClientContext, { ClientConfig } from '../../../lib/contracts/IClientContext';
+import { PrimaryKeysRequest } from '../../../lib/contracts/IDBSQLSession';
 import IDBSQLLogger, { LogLevel } from '../../../lib/contracts/IDBSQLLogger';
 import HiveDriverError from '../../../lib/errors/HiveDriverError';
 import ParameterError from '../../../lib/errors/ParameterError';
@@ -1094,25 +1095,23 @@ describe('KernelSessionBackend', () => {
     ]);
   });
 
-  it('getPrimaryKeys rejects an omitted catalog up front (the kernel requires one)', async () => {
+  it('getPrimaryKeys forwards null, omitted, and empty namespace names unchanged', async () => {
     const connection = new FakeNativeConnection();
     const session = makeSession(connection);
-    for (const request of [
-      { schemaName: 'def', tableName: 't' },
-      { catalogName: '', schemaName: 'def', tableName: 't' },
-    ]) {
-      let thrown: unknown;
-      try {
+    const expected: unknown[][] = [];
+    for (const catalogName of [undefined, null, '', 'main']) {
+      for (const schemaName of [undefined, null, '', 'def']) {
         // eslint-disable-next-line no-await-in-loop
-        await session.getPrimaryKeys(request);
-      } catch (err) {
-        thrown = err;
+        const operation = await session.getPrimaryKeys({
+          catalogName,
+          schemaName,
+          tableName: 't',
+        } as PrimaryKeysRequest);
+        expect(operation).to.be.instanceOf(KernelOperationBackend);
+        expected.push(['getPrimaryKeys', catalogName, schemaName, 't']);
       }
-      expect(thrown, `expected reject for ${JSON.stringify(request)}`).to.be.instanceOf(HiveDriverError);
-      expect((thrown as Error).message).to.match(/requires a catalog/);
     }
-    // The kernel call must NOT be reached (no empty-identifier sent over FFI).
-    expect(connection.metadataCalls.filter((c) => c[0] === 'getPrimaryKeys')).to.have.length(0);
+    expect(connection.metadataCalls).to.deep.equal(expected);
   });
 
   it('getInfo synthesizes the three server-answered info types and rejects the rest', async () => {