fix(dameng): support low-privilege schema loading

agents/drivers/dameng/src/main/java/com/dbx/agent/dameng/DamengAgent.java

@@ -26,6 +26,7 @@ import java.sql.Connection;
 import java.sql.DriverManager;
 import java.sql.PreparedStatement;
 import java.sql.ResultSet;
+import java.sql.SQLException;
 import java.sql.SQLXML;
 import java.sql.Statement;
 import java.sql.Types;
@@ -73,7 +74,7 @@ public final class DamengAgent extends BaseDatabaseAgent {
         """.stripIndent().trim();
     private static final Set<String> SYSTEM_USERS = Set.of(
         "SYS", "SYSAUDITOR", "SYSSSO", "CTISYS",
-        "SYS_DBA", "_SYS_STATISTICS", "SYS_PHM"
+        "SYSDBA", "SYS_DBA", "_SYS_STATISTICS", "SYS_PHM"
     );
 
     private Connection connection;
@@ -140,7 +141,18 @@ public final class DamengAgent extends BaseDatabaseAgent {
 
     @Override
     public List<String> listSchemas() {
-        return unchecked(this::listVisibleSchemas);
+        return unchecked(() -> {
+            try {
+                return listVisibleSchemas();
+            } catch (SQLException catalogError) {
+                try {
+                    return listVisibleUsers();
+                } catch (Exception fallbackError) {
+                    catalogError.addSuppressed(fallbackError);
+                    throw catalogError;
+                }
+            }
+        });
     }
 
     private List<String> listVisibleUsers() throws Exception {

agents/drivers/dameng/src/test/java/com/dbx/agent/dameng/DamengAgentMetadataTest.java

@@ -112,6 +112,20 @@ class DamengAgentMetadataTest {
         Assertions.assertTrue(sqls.stream().noneMatch(sql -> sql.contains("ALL_OBJECTS")), String.join("\n", sqls));
     }
 
+    @Test
+    void listSchemasFallsBackToAllUsersWithoutSysObjectsPrivilege() {
+        DamengAgent agent = new DamengAgent();
+        List<String> sqls = new ArrayList<>();
+        TestSupport.setPrivateConnection(agent, restrictedSchemaConnection(sqls));
+
+        List<String> schemas = agent.listSchemas();
+
+        Assertions.assertEquals(List.of("APP", "REPORTING"), schemas);
+        Assertions.assertEquals(2, sqls.size(), String.join("\n", sqls));
+        Assertions.assertTrue(sqls.get(0).contains("SYS.SYSOBJECTS"), sqls.get(0));
+        Assertions.assertTrue(sqls.get(1).contains("ALL_USERS"), sqls.get(1));
+    }
+
     @Test
     void mapsMaterializedViewsFromMetadata() {
         DamengAgent agent = new DamengAgent();
@@ -696,6 +710,30 @@ class DamengAgentMetadataTest {
         });
     }
 
+    private static Connection restrictedSchemaConnection(List<String> sqls) {
+        return proxy(Connection.class, (method, args) -> {
+            String name = method.getName();
+            if ("prepareStatement".equals(name)) {
+                String sql = (String) args[0];
+                sqls.add(sql);
+                if (sql.contains("SYS.SYSOBJECTS")) {
+                    return failingMetadataStatement("no SYS.SYSOBJECTS privilege");
+                }
+                if (sql.contains("ALL_USERS")) {
+                    return metadataStatement(List.of(List.of("APP"), List.of("REPORTING")));
+                }
+                throw new AssertionError("Unexpected SQL: " + sql);
+            }
+            if ("close".equals(name)) {
+                return null;
+            }
+            if ("isClosed".equals(name)) {
+                return false;
+            }
+            return defaultValue(method.getReturnType());
+        });
+    }
+
     private static PreparedStatement failingMetadataStatement(String message) {
         return proxy(PreparedStatement.class, (method, args) -> {
             if ("executeQuery".equals(method.getName())) {