small nits and moving examples into _test files

.gitignore

@@ -3,3 +3,5 @@
 run.sh
 duckdb/
 .idea
+./duckdb
+duckdb

duckdb_test.go

@@ -5,6 +5,8 @@ import (
 	"database/sql"
 	"database/sql/driver"
 	"encoding/json"
+	"fmt"
+	"log"
 	"math/big"
 	"os"
 	"reflect"
@@ -88,6 +90,38 @@ func TestConnector_Close(t *testing.T) {
 	require.NoError(t, connector.Close())
 }
 
+func ExampleNewConnector() {
+	c, err := NewConnector("duckdb?access_mode=READ_WRITE", func(execer driver.ExecerContext) error {
+		initQueries := []string{
+			`SET memory_limit = '10GB';`,
+			`SET threads TO 1;`,
+		}
+
+		ctx := context.Background()
+		for _, query := range initQueries {
+			_, err := execer.ExecContext(ctx, query, nil)
+			if err != nil {
+				return err
+			}
+		}
+		return nil
+	})
+	checkErr(err, "failed to create new duckdb connector: %s")
+	defer c.Close()
+
+	db := sql.OpenDB(c)
+	defer db.Close()
+
+	var value string
+	row := db.QueryRow(`SELECT value FROM duckdb_settings() WHERE name = 'memory_limit';`)
+	if row.Scan(&value) != nil {
+		log.Fatalf("failed to scan row: %s", err)
+	}
+
+	fmt.Printf("Setting memory_limit is %s", value)
+	// Output: Setting memory_limit is 9.3 GiB
+}
+
 func TestConnPool(t *testing.T) {
 	db := openDB(t)
 	db.SetMaxOpenConns(2) // set connection pool size greater than 1
@@ -629,6 +663,28 @@ func TestQueryTimeout(t *testing.T) {
 	require.NoError(t, db.Close())
 }
 
+func Example_simpleConnection() {
+	// Connect to DuckDB using '[database/sql.Open]'.
+	db, err := sql.Open("duckdb", "?access_mode=READ_WRITE")
+	checkErr(err, "failed to open connection to duckdb: %s")
+	defer db.Close()
+
+	ctx := context.Background()
+
+	createStmt := `CREATE table users(name VARCHAR, age INTEGER)`
+	_, err = db.ExecContext(ctx, createStmt)
+	checkErr(err, "failed to create table: %s")
+
+	insertStmt := `INSERT INTO users(name, age) VALUES (?, ?);`
+	res, err := db.ExecContext(ctx, insertStmt, "Marc", 30)
+	checkErr(err, "failed to insert users: %s")
+
+	rowsAffected, err := res.RowsAffected()
+	checkErr(err, "failed to get number of rows affected")
+	fmt.Printf("Inserted %d row(s) into users table", rowsAffected)
+	// Output: Inserted 1 row(s) into users table
+}
+
 func openDB(t *testing.T) *sql.DB {
 	db, err := sql.Open("duckdb", "")
 	require.NoError(t, err)
@@ -645,3 +701,9 @@ func createTable(db *sql.DB, t *testing.T, sql string) *sql.Result {
 func createFooTable(db *sql.DB, t *testing.T) *sql.Result {
 	return createTable(db, t, `CREATE TABLE foo(bar VARCHAR, baz INTEGER)`)
 }
+
+func checkErr(err error, msg string) {
+	if err != nil {
+		log.Fatalf(msg, err)
+	}
+}

errors.go

@@ -91,7 +91,7 @@ var (
 
 	errUnsupportedMapKeyType = errors.New("MAP key type not supported")
 	errEmptyName             = errors.New("empty name")
-	errInvalidDecimalWidth   = fmt.Errorf("the DECIMAL with must be between 1 and %d", MAX_DECIMAL_WIDTH)
+	errInvalidDecimalWidth   = fmt.Errorf("the DECIMAL with must be between 1 and %d", max_decimal_width)
 	errInvalidDecimalScale   = errors.New("the DECIMAL scale must be less than or equal to the width")
 	errSetSQLNULLValue       = errors.New("cannot write to a NULL column")
 

type_info.go

@@ -114,7 +114,7 @@ func NewTypeInfo(t Type) (TypeInfo, error) {
 // NewDecimalInfo returns DECIMAL type information.
 // Its input parameters are the width and scale of the DECIMAL type.
 func NewDecimalInfo(width uint8, scale uint8) (TypeInfo, error) {
-	if width < 1 || width > MAX_DECIMAL_WIDTH {
+	if width < 1 || width > max_decimal_width {
 		return nil, getError(errAPI, errInvalidDecimalWidth)
 	}
 	if scale > width {

types.go

@@ -21,12 +21,12 @@ func convertNumericType[srcT numericType, destT numericType](val srcT) destT {
 	return destT(val)
 }
 
-const UUIDLength = 16
+const uuid_length = 16
 
-type UUID [UUIDLength]byte
+type UUID [uuid_length]byte
 
 func (u *UUID) Scan(v any) error {
-	if n := copy(u[:], v.([]byte)); n != UUIDLength {
+	if n := copy(u[:], v.([]byte)); n != uuid_length {
 		return fmt.Errorf("invalid UUID length: %d", n)
 	}
 	return nil
@@ -36,7 +36,7 @@ func (u *UUID) Scan(v any) error {
 // The value is computed as: upper * 2^64 + lower
 
 func hugeIntToUUID(hi C.duckdb_hugeint) []byte {
-	var uuid [UUIDLength]byte
+	var uuid [uuid_length]byte
 	// We need to flip the sign bit of the signed hugeint to transform it to UUID bytes
 	binary.BigEndian.PutUint64(uuid[:8], uint64(hi.upper)^1<<63)
 	binary.BigEndian.PutUint64(uuid[8:], uint64(hi.lower))
@@ -117,7 +117,7 @@ func (s *Composite[T]) Scan(v any) error {
 	return mapstructure.Decode(v, &s.t)
 }
 
-const MAX_DECIMAL_WIDTH = 38
+const max_decimal_width = 38
 
 type Decimal struct {
 	Width uint8

vector_setters.go

@@ -395,10 +395,10 @@ func setUUID[S any](vec *vector, rowIdx C.idx_t, val S) error {
 	case UUID:
 		uuid = v
 	case []uint8:
-		if len(v) != UUIDLength {
+		if len(v) != uuid_length {
 			return castError(reflect.TypeOf(val).String(), reflect.TypeOf(uuid).String())
 		}
-		for i := 0; i < UUIDLength; i++ {
+		for i := 0; i < uuid_length; i++ {
 			uuid[i] = v[i]
 		}
 	default: