Use chdb stable ABI v2 for standard golang err handling

README.md

@@ -30,40 +30,11 @@
 ./chdb-go --path /tmp/chdb # interactive persistent mode
 ```
 
-3. Shortcuts
-
-- `\l` to list databases;
-- `\dt dbname` to list tables in database;
-
 ```bash
 chdb-io/chdb-go [main] » ./chdb-go 
 Enter your SQL commands; type 'exit' to quit.
  :) CREATE DATABASE IF NOT EXISTS testdb;
 
- :) \l
-┏━━━━━━━━━━━━━━━━━━━━┓
-┃ name               ┃
-┡━━━━━━━━━━━━━━━━━━━━┩
-│ INFORMATION_SCHEMA │
-├────────────────────┤
-│ _local             │
-├────────────────────┤
-│ information_schema │
-├────────────────────┤
-│ system             │
-├────────────────────┤
-│ testdb             │
-└────────────────────┘
-
- :) CREATE TABLE IF NOT EXISTS testdb.testtable (id UInt32) ENGINE = MergeTree()
-:-] ORDER BY id;
-
- :) \dt testdb
-┏━━━━━━━━━━━┓
-┃ name      ┃
-┡━━━━━━━━━━━┩
-│ testtable │
-└───────────┘
 
 ```
 
@@ -72,34 +43,50 @@ Enter your SQL commands; type 'exit' to quit.
 package main
 
 import (
-    "fmt"
-    "github.com/chdb-io/chdb-go/chdb"
+	"fmt"
+	"os"
+	"path/filepath"
+
+	"github.com/chdb-io/chdb-go/chdb"
 )
 
 func main() {
-    // Stateless Query (ephemeral)
-    result := chdb.Query("SELECT version()", "CSV")
-    fmt.Println(result)
-
-    // Stateful Query (persistent)
-    session, _ := NewSession(path)
-    defer session.Cleanup()
-
-    session.Query("CREATE DATABASE IF NOT EXISTS testdb; " +
-    "CREATE TABLE IF NOT EXISTS testdb.testtable (id UInt32) ENGINE = MergeTree() ORDER BY id;")
-
-    session.Query("USE testdb; INSERT INTO testtable VALUES (1), (2), (3);")
-
-    ret := session.Query("SELECT * FROM testtable;")
-    fmt.Println(ret)
+	// Stateless Query (ephemeral)
+	result, err := chdb.Query("SELECT version()", "CSV")
+	if err != nil {
+		fmt.Println(err)
+	}
+	fmt.Println(result)
+
+	tmp_path := filepath.Join(os.TempDir(), "chdb_test")
+	defer os.RemoveAll(tmp_path)
+	// Stateful Query (persistent)
+	session, _ := chdb.NewSession(tmp_path)
+	defer session.Cleanup()
+
+	_, err = session.Query("CREATE DATABASE IF NOT EXISTS testdb; " +
+		"CREATE TABLE IF NOT EXISTS testdb.testtable (id UInt32) ENGINE = MergeTree() ORDER BY id;")
+	if err != nil {
+		fmt.Println(err)
+		return
+	}
+
+	_, err = session.Query("USE testdb; INSERT INTO testtable VALUES (1), (2), (3);")
+	if err != nil {
+		fmt.Println(err)
+		return
+	}
+
+	ret, err := session.Query("SELECT * FROM testtable;")
+	if err != nil {
+		fmt.Println(err)
+	} else {
+		fmt.Println(ret)
+	}
 }
 ```
 
 ### Golang API docs
 
 - See [lowApi.md](lowApi.md) for the low level APIs.
 - See [chdb.md](chdb.md) for high level APIs.
-
-### Thanks
-
-- cli implementation is based on [clickhouse-cli](https://github.com/memlimit/clickhouse-cli)

chdb/driver/driver.go

@@ -27,7 +27,7 @@ func init() {
 	sql.Register("chdb", Driver{})
 }
 
-type queryHandle func(string, ...string) *chdbstable.LocalResult
+type queryHandle func(string, ...string) (*chdbstable.LocalResult, error)
 
 type connector struct {
 	udfPath string
@@ -127,7 +127,10 @@ func (c *conn) Query(query string, values []driver.Value) (driver.Rows, error) {
 }
 
 func (c *conn) QueryContext(ctx context.Context, query string, args []driver.NamedValue) (driver.Rows, error) {
-	result := c.QueryFun(query, "Arrow", c.udfPath)
+	result, err := c.QueryFun(query, "Arrow", c.udfPath)
+	if err != nil {
+		return nil, err
+	}
 	buf := result.Buf()
 	if buf == nil {
 		return nil, fmt.Errorf("result is nil")

chdb/driver/driver_test.go

@@ -90,7 +90,10 @@ func TestDbWithSession(t *testing.T) {
 
 	session.Query("USE testdb; INSERT INTO testtable VALUES (1), (2), (3);")
 
-	ret := session.Query("SELECT * FROM testtable;")
+	ret, err := session.Query("SELECT * FROM testtable;")
+	if err != nil {
+		t.Fatalf("Query fail, err: %s", err)
+	}
 	if string(ret.Buf()) != "1\n2\n3\n" {
 		t.Errorf("Query result should be 1\n2\n3\n, got %s", string(ret.Buf()))
 	}

chdb/session.go

@@ -36,7 +36,7 @@ func NewSession(paths ...string) (*Session, error) {
 }
 
 // Query calls queryToBuffer with a default output format of "CSV" if not provided.
-func (s *Session) Query(queryStr string, outputFormats ...string) *chdbstable.LocalResult {
+func (s *Session) Query(queryStr string, outputFormats ...string) (result *chdbstable.LocalResult, err error) {
 	outputFormat := "CSV" // Default value
 	if len(outputFormats) > 0 {
 		outputFormat = outputFormats[0]

chdb/session_test.go

@@ -64,7 +64,10 @@ func TestQuery(t *testing.T) {
 
 	session.Query("USE testdb; INSERT INTO testtable VALUES (1), (2), (3);")
 
-	ret := session.Query("SELECT * FROM testtable;")
+	ret, err := session.Query("SELECT * FROM testtable;")
+	if err != nil {
+		t.Errorf("Query failed: %s", err)
+	}
 	if string(ret.Buf()) != "1\n2\n3\n" {
 		t.Errorf("Query result should be 1\n2\n3\n, got %s", string(ret.Buf()))
 	}

chdb/wrapper.go

@@ -5,7 +5,7 @@ import (
 )
 
 // Query calls queryToBuffer with a default output format of "CSV" if not provided.
-func Query(queryStr string, outputFormats ...string) *chdbstable.LocalResult {
+func Query(queryStr string, outputFormats ...string) (result *chdbstable.LocalResult, err error) {
 	outputFormat := "CSV" // Default value
 	if len(outputFormats) > 0 {
 		outputFormat = outputFormats[0]
@@ -14,7 +14,7 @@ func Query(queryStr string, outputFormats ...string) *chdbstable.LocalResult {
 }
 
 // queryToBuffer constructs the arguments for QueryStable and calls it.
-func queryToBuffer(queryStr, outputFormat, path, udfPath string) *chdbstable.LocalResult {
+func queryToBuffer(queryStr, outputFormat, path, udfPath string) (result *chdbstable.LocalResult, err error) {
 	argv := []string{"clickhouse", "--multiquery"}
 
 	// Handle output format

chdb/wrapper_test.go

@@ -1,17 +1,14 @@
 package chdb
 
 import (
-	"io/ioutil"
 	"os"
+	"path/filepath"
 	"testing"
 )
 
 func TestQueryToBuffer(t *testing.T) {
 	// Create a temporary directory
-	tempDir, err := ioutil.TempDir("", "example")
-	if err != nil {
-		t.Fatalf("Failed to create temporary directory: %v", err)
-	}
+	tempDir := filepath.Join(os.TempDir(), "chdb_test")
 	defer os.RemoveAll(tempDir)
 
 	// Define test cases
@@ -21,6 +18,7 @@ func TestQueryToBuffer(t *testing.T) {
 		outputFormat   string
 		path           string
 		udfPath        string
+		expectedErrMsg string
 		expectedResult string
 	}{
 		{
@@ -29,6 +27,7 @@ func TestQueryToBuffer(t *testing.T) {
 			outputFormat:   "CSV",
 			path:           "",
 			udfPath:        "",
+			expectedErrMsg: "",
 			expectedResult: "123\n",
 		},
 		// Session
@@ -39,35 +38,59 @@ func TestQueryToBuffer(t *testing.T) {
 			outputFormat:   "CSV",
 			path:           tempDir,
 			udfPath:        "",
+			expectedErrMsg: "",
 			expectedResult: "",
 		},
+		// {
+		// 	name:           "Session Query 2",
+		// 	queryStr:       "USE testdb; INSERT INTO testtable VALUES (1), (2), (3);",
+		// 	outputFormat:   "CSV",
+		// 	path:           tempDir,
+		// 	udfPath:        "",
+		// 	expectedErrMsg: "",
+		// 	expectedResult: "",
+		// },
+		// {
+		// 	name:           "Session Query 3",
+		// 	queryStr:       "SELECT * FROM testtable;",
+		// 	outputFormat:   "CSV",
+		// 	path:           tempDir,
+		// 	udfPath:        "",
+		// 	expectedErrMsg: "",
+		// 	expectedResult: "1\n2\n3\n",
+		// },
 		{
-			name:           "Session Query 2",
-			queryStr:       "USE testdb; INSERT INTO testtable VALUES (1), (2), (3);",
+			name:           "Error Query",
+			queryStr:       "SELECT * FROM nonexist; ",
 			outputFormat:   "CSV",
 			path:           tempDir,
 			udfPath:        "",
+			expectedErrMsg: "Code: 60. DB::Exception: Table _local.nonexist does not exist. (UNKNOWN_TABLE)",
 			expectedResult: "",
 		},
-		{
-			name:           "Session Query 3",
-			queryStr:       "SELECT * FROM testtable;",
-			outputFormat:   "CSV",
-			path:           tempDir,
-			udfPath:        "",
-			expectedResult: "1\n2\n3\n",
-		},
 	}
 
 	for _, tc := range testCases {
 		t.Run(tc.name, func(t *testing.T) {
 			// Call queryToBuffer
-			result := queryToBuffer(tc.queryStr, tc.outputFormat, tc.path, tc.udfPath)
+			result, err := queryToBuffer(tc.queryStr, tc.outputFormat, tc.path, tc.udfPath)
 
 			// Verify
-			if string(result.Buf()) != tc.expectedResult {
-				t.Errorf("%v queryToBuffer() with queryStr %v, outputFormat %v, path %v, udfPath %v, expect result: %v, got result: %v",
-					tc.name, tc.queryStr, tc.outputFormat, tc.path, tc.udfPath, tc.expectedResult, string(result.Buf()))
+			if tc.expectedErrMsg != "" {
+				if err == nil {
+					t.Errorf("%v queryToBuffer() with queryStr %v, outputFormat %v, path %v, udfPath %v, expect error message: %v, got no error",
+						tc.name, tc.queryStr, tc.outputFormat, tc.path, tc.udfPath, tc.expectedErrMsg)
+				} else {
+					if err.Error() != tc.expectedErrMsg {
+						t.Errorf("%v queryToBuffer() with queryStr %v, outputFormat %v, path %v, udfPath %v, expect error message: %v, got error message: %v",
+							tc.name, tc.queryStr, tc.outputFormat, tc.path, tc.udfPath, tc.expectedErrMsg, err.Error())
+					}
+				}
+			} else {
+				if string(result.Buf()) != tc.expectedResult {
+					t.Errorf("%v queryToBuffer() with queryStr %v, outputFormat %v, path %v, udfPath %v, expect result: %v, got result: %v",
+						tc.name, tc.queryStr, tc.outputFormat, tc.path, tc.udfPath, tc.expectedResult, string(result.Buf()))
+				}
 			}
 		})
 	}

chdbstable/chdb.go

@@ -7,40 +7,62 @@ package chdbstable
 */
 import "C"
 import (
+	"errors"
 	"runtime"
 	"unsafe"
 )
 
-// LocalResult mirrors the C struct local_result in Go.
+// ChdbError is returned when the C function returns an error.
+type ChdbError struct {
+	msg string
+}
+
+func (e *ChdbError) Error() string {
+	return e.msg
+}
+
+// ErrNilResult is returned when the C function returns a nil pointer.
+var ErrNilResult = errors.New("chDB C function returned nil pointer")
+
+// LocalResult mirrors the C struct local_result_v2 in Go.
 type LocalResult struct {
-	cResult *C.struct_local_result
+	cResult *C.struct_local_result_v2
 }
 
 // newLocalResult creates a new LocalResult and sets a finalizer to free C memory.
-func newLocalResult(cResult *C.struct_local_result) *LocalResult {
+func newLocalResult(cResult *C.struct_local_result_v2) *LocalResult {
 	result := &LocalResult{cResult: cResult}
 	runtime.SetFinalizer(result, freeLocalResult)
 	return result
 }
 
 // freeLocalResult is called by the garbage collector.
 func freeLocalResult(result *LocalResult) {
-	C.free_result(result.cResult)
+	C.free_result_v2(result.cResult)
 }
 
-// QueryStable calls the C function query_stable.
-func QueryStable(argc int, argv []string) *LocalResult {
+// QueryStable calls the C function query_stable_v2.
+func QueryStable(argc int, argv []string) (result *LocalResult, err error) {
 	cArgv := make([]*C.char, len(argv))
 	for i, s := range argv {
 		cArgv[i] = C.CString(s)
 		defer C.free(unsafe.Pointer(cArgv[i]))
 	}
 
-	cResult := C.query_stable(C.int(argc), &cArgv[0])
-	return newLocalResult(cResult)
+	cResult := C.query_stable_v2(C.int(argc), &cArgv[0])
+	if cResult == nil {
+		// According to the C ABI of chDB v1.2.0, the C function query_stable_v2
+		// returns nil if the query returns no data. This is not an error. We
+		// will change this behavior in the future.
+		return newLocalResult(cResult), nil
+	}
+	if cResult.error_message != nil {
+		return nil, &ChdbError{msg: C.GoString(cResult.error_message)}
+	}
+	return newLocalResult(cResult), nil
 }
 
-// Accessor methods to access fields of the local_result struct.
+// Accessor methods to access fields of the local_result_v2 struct.
 func (r *LocalResult) Buf() []byte {
 	if r.cResult == nil {
 		return nil

chdbstable/chdb.h

@@ -10,7 +10,7 @@ extern "C" {
 #endif
 
 #define CHDB_EXPORT __attribute__((visibility("default")))
-struct CHDB_EXPORT local_result
+struct local_result
 {
     char * buf;
     size_t len;
@@ -20,9 +20,23 @@ struct CHDB_EXPORT local_result
     uint64_t bytes_read;
 };
 
+struct local_result_v2
+{
+    char * buf;
+    size_t len;
+    void * _vec; // std::vector<char> *, for freeing
+    double elapsed;
+    uint64_t rows_read;
+    uint64_t bytes_read;
+    char * error_message;
+};
+
 CHDB_EXPORT struct local_result * query_stable(int argc, char ** argv);
 CHDB_EXPORT void free_result(struct local_result * result);
 
+CHDB_EXPORT struct local_result_v2 * query_stable_v2(int argc, char ** argv);
+CHDB_EXPORT void free_result_v2(struct local_result_v2 * result);
+
 #ifdef __cplusplus
 }
 #endif