fix(kingbase): prioritize selected schema search path

agents/common/src/main/java/com/dbx/agent/BatchExecutor.java

@@ -79,26 +79,7 @@ public final class BatchExecutor {
     }
 
     private static void applySchema(Connection conn, String schema, Function<String, String> setSchemaSql) throws Exception {
-        if (schema == null || schema.trim().isEmpty()) {
-            return;
-        }
-        try {
-            conn.setSchema(schema);
-            return;
-        } catch (Exception | AbstractMethodError ignored) {
-        }
-        try {
-            conn.setCatalog(schema);
-            return;
-        } catch (Exception | AbstractMethodError ignored) {
-        }
-        String schemaSql = setSchemaSql.apply(schema);
-        if (schemaSql == null || schemaSql.trim().isEmpty()) {
-            return;
-        }
-        try (Statement stmt = conn.createStatement()) {
-            stmt.execute(schemaSql);
-        }
+        JdbcSchemaSwitcher.apply(conn, schema, setSchemaSql);
     }
 
     private static <T> T unchecked(ThrowingSupplier<T> supplier) {

agents/common/src/main/java/com/dbx/agent/JdbcExecutor.java

@@ -565,31 +565,12 @@ public final class JdbcExecutor {
     }
 
     private void applySchema(Connection conn, String schema, Function<String, String> setSchemaSql) throws SQLException {
-        if (schema == null || schema.trim().isEmpty()) {
-            return;
-        }
-        // Prefer JDBC standard APIs over database-specific SQL.
-        // setSchema (JDBC 4.1) and setCatalog (JDBC 1.0) work universally
-        // across all JDBC drivers without needing to know the database dialect.
         try {
-            conn.setSchema(schema);
-            return;
-        } catch (SQLException | AbstractMethodError ignored) {
-            // setSchema not supported by this driver
-        }
-        try {
-            conn.setCatalog(schema);
-            return;
-        } catch (SQLException | AbstractMethodError ignored) {
-            // setCatalog not supported either
-        }
-        // Fallback: execute database-specific SQL (e.g. USE, SET SCHEMA, etc.)
-        String schemaSql = setSchemaSql.apply(schema);
-        if (schemaSql == null || schemaSql.trim().isEmpty()) {
-            return;
-        }
-        try (Statement stmt = conn.createStatement()) {
-            stmt.execute(schemaSql);
+            JdbcSchemaSwitcher.apply(conn, schema, setSchemaSql);
+        } catch (SQLException e) {
+            throw e;
+        } catch (Exception e) {
+            throw new SQLException(e);
         }
     }
 

agents/common/src/main/java/com/dbx/agent/JdbcSchemaSwitcher.java

@@ -0,0 +1,68 @@
+package com.dbx.agent;
+
+import java.sql.Connection;
+import java.sql.SQLException;
+import java.sql.Statement;
+import java.util.function.Function;
+
+final class JdbcSchemaSwitcher {
+    private JdbcSchemaSwitcher() {
+    }
+
+    static void apply(Connection conn, String schema, Function<String, String> setSchemaSql) throws Exception {
+        if (schema == null || schema.trim().isEmpty()) {
+            return;
+        }
+
+        SchemaSqlResult schemaSqlResult = applySchemaSql(conn, schema, setSchemaSql);
+        Exception schemaSqlError = schemaSqlResult.error;
+        if (schemaSqlError == null) {
+            return;
+        }
+
+        try {
+            conn.setSchema(schema);
+            return;
+        } catch (SQLException | AbstractMethodError ignored) {
+            // Some JDBC drivers only expose schema switching through SQL.
+        }
+        try {
+            conn.setCatalog(schema);
+            return;
+        } catch (SQLException | AbstractMethodError ignored) {
+            // Last fallback failed as well; surface the SQL-switch error below.
+        }
+
+        if (schemaSqlResult.attempted) {
+            throw schemaSqlError;
+        }
+    }
+
+    private static SchemaSqlResult applySchemaSql(Connection conn, String schema, Function<String, String> setSchemaSql) {
+        String schemaSql;
+        try {
+            schemaSql = setSchemaSql.apply(schema);
+        } catch (RuntimeException e) {
+            return new SchemaSqlResult(true, e);
+        }
+        if (schemaSql == null || schemaSql.trim().isEmpty()) {
+            return new SchemaSqlResult(false, new SQLException("No schema switch SQL provided"));
+        }
+        try (Statement stmt = conn.createStatement()) {
+            stmt.execute(schemaSql);
+            return new SchemaSqlResult(true, null);
+        } catch (SQLException | AbstractMethodError e) {
+            return new SchemaSqlResult(true, e instanceof SQLException ? (SQLException) e : new SQLException(e));
+        }
+    }
+
+    private static final class SchemaSqlResult {
+        private final boolean attempted;
+        private final Exception error;
+
+        private SchemaSqlResult(boolean attempted, Exception error) {
+            this.attempted = attempted;
+            this.error = error;
+        }
+    }
+}

agents/common/src/main/java/com/dbx/agent/TransactionExecutor.java

@@ -71,30 +71,7 @@ public final class TransactionExecutor {
     }
 
     private static void applySchema(Connection conn, String schema, Function<String, String> setSchemaSql) throws Exception {
-        if (schema == null || schema.trim().isEmpty()) {
-            return;
-        }
-        // Prefer JDBC standard APIs over database-specific SQL.
-        try {
-            conn.setSchema(schema);
-            return;
-        } catch (Exception | AbstractMethodError ignored) {
-            // setSchema not supported by this driver
-        }
-        try {
-            conn.setCatalog(schema);
-            return;
-        } catch (Exception | AbstractMethodError ignored) {
-            // setCatalog not supported either
-        }
-        // Fallback: execute database-specific SQL (e.g. USE, SET SCHEMA, etc.)
-        String schemaSql = setSchemaSql.apply(schema);
-        if (schemaSql == null || schemaSql.trim().isEmpty()) {
-            return;
-        }
-        try (Statement stmt = conn.createStatement()) {
-            stmt.execute(schemaSql);
-        }
+        JdbcSchemaSwitcher.apply(conn, schema, setSchemaSql);
     }
 
     private static boolean supportsTransactions(Connection conn) {