Revert "stdlib matches native pgx scanning support"

This reverts commit f6980e4.

The enabling change was reverted from Go. It was determined that a
different interface could not only provide the new functionality, but
also improve performance.

refs: #2403

Author: jackc

pgtype/pgtype.go

@@ -1980,8 +1980,6 @@ func (m *Map) Encode(oid uint32, formatCode int16, value any, buf []byte) (newBu
 //
 // This uses the type of v to look up the PostgreSQL OID that v presumably came from. This means v must be registered
 // with m by calling RegisterDefaultPgType.
-//
-// As of Go 1.26, this should be unnecessary.
 func (m *Map) SQLScanner(v any) sql.Scanner {
 	if s, ok := v.(sql.Scanner); ok {
 		return s

stdlib/bench_test.go

@@ -8,8 +8,6 @@ import (
 	"strings"
 	"testing"
 	"time"
-
-	"github.com/jackc/pgx/v5/pgtype"
 )
 
 func getSelectRowsCounts(b *testing.B) []int64 {
@@ -109,48 +107,3 @@ func BenchmarkSelectRowsScanNull(b *testing.B) {
 		})
 	}
 }
-
-func BenchmarkFlatArrayEncodeArgument(b *testing.B) {
-	db := openDB(b)
-	defer closeDB(b, db)
-
-	input := make(pgtype.FlatArray[string], 10)
-	for i := range input {
-		input[i] = fmt.Sprintf("String %d", i)
-	}
-
-	for b.Loop() {
-		var n int64
-		err := db.QueryRow("select cardinality($1::text[])", input).Scan(&n)
-		if err != nil {
-			b.Fatal(err)
-		}
-		if n != int64(len(input)) {
-			b.Fatalf("Expected %d, got %d", len(input), n)
-		}
-	}
-}
-
-func BenchmarkFlatArrayScanResult(b *testing.B) {
-	db := openDB(b)
-	defer closeDB(b, db)
-
-	var input string
-	for i := range 10 {
-		if i > 0 {
-			input += ","
-		}
-		input += fmt.Sprintf(`'String %d'`, i)
-	}
-
-	for b.Loop() {
-		var result pgtype.FlatArray[string]
-		err := db.QueryRow(fmt.Sprintf("select array[%s]::text[]", input)).Scan(&result)
-		if err != nil {
-			b.Fatal(err)
-		}
-		if len(result) != 10 {
-			b.Fatalf("Expected %d, got %d", len(result), 10)
-		}
-	}
-}

stdlib/sql.go

@@ -57,24 +57,12 @@
 //
 // # PostgreSQL Specific Data Types
 //
-// As of Go 1.26 the database/sql allows drivers to implement their own scanning logic by implementing the
-// driver.RowsColumnScanner interface. This allows PostgreSQL arrays to be scanned directly into Go slices.
-//
-//	var a []int64
-//	err := db.QueryRow("select '{1,2,3}'::bigint[]").Scan(&a)
-//
-// In older versions of Go, *pgtype.Map.SQLScanner can be used as an adapter that makes these types usable as a
-// sql.Scanner.
+// The pgtype package provides support for PostgreSQL specific types. *pgtype.Map.SQLScanner is an adapter that makes
+// these types usable as a sql.Scanner.
 //
 //	m := pgtype.NewMap()
 //	var a []int64
 //	err := db.QueryRow("select '{1,2,3}'::bigint[]").Scan(m.SQLScanner(&a))
-//
-// The pgtype package provides support for PostgreSQL specific types. These types can be used directly in Go 1.26 and
-// with *pgtype.Map.SQLScanner in older Go versions.
-//
-//	var r pgtype.Range[pgtype.Int4]
-//	err := db.QueryRow("select int4range(1, 5)").Scan(&r)
 package stdlib
 
 import (
@@ -903,12 +891,6 @@ func convertNamedArguments(args []any, argsV []driver.NamedValue) {
 	}
 }
 
-func (r *Rows) ScanColumn(dest any, index int) error {
-	m := r.conn.conn.TypeMap()
-	fd := r.rows.FieldDescriptions()[index]
-	return m.Scan(fd.DataTypeOID, fd.Format, r.rows.RawValues()[index], dest)
-}
-
 type wrapTx struct {
 	ctx context.Context
 	tx  pgx.Tx

stdlib/sql_go1.26_test.go

@@ -110,32 +110,6 @@ func testWithAllQueryExecModes(t *testing.T, f func(t *testing.T, db *sql.DB)) {
 	}
 }
 
-func testWithKnownOIDQueryExecModes(t *testing.T, f func(t *testing.T, db *sql.DB)) {
-	for _, mode := range []pgx.QueryExecMode{
-		pgx.QueryExecModeCacheStatement,
-		pgx.QueryExecModeCacheDescribe,
-		pgx.QueryExecModeDescribeExec,
-	} {
-		t.Run(mode.String(),
-			func(t *testing.T) {
-				config, err := pgx.ParseConfig(os.Getenv("PGX_TEST_DATABASE"))
-				require.NoError(t, err)
-
-				config.DefaultQueryExecMode = mode
-				db := stdlib.OpenDB(*config)
-				defer func() {
-					err := db.Close()
-					require.NoError(t, err)
-				}()
-
-				f(t, db)
-
-				ensureDBValid(t, db)
-			},
-		)
-	}
-}
-
 // Do a simple query to ensure the DB is still usable. This is of less use in stdlib as the connection pool should
 // cover broken connections.
 func ensureDBValid(t testing.TB, db *sql.DB) {
@@ -537,6 +511,43 @@ func TestConnQueryScanGoArray(t *testing.T) {
 	})
 }
 
+func TestConnQueryScanArray(t *testing.T) {
+	testWithAllQueryExecModes(t, func(t *testing.T, db *sql.DB) {
+		m := pgtype.NewMap()
+
+		var a pgtype.Array[int64]
+		err := db.QueryRow("select '{1,2,3}'::bigint[]").Scan(m.SQLScanner(&a))
+		require.NoError(t, err)
+		assert.Equal(t, pgtype.Array[int64]{Elements: []int64{1, 2, 3}, Dims: []pgtype.ArrayDimension{{Length: 3, LowerBound: 1}}, Valid: true}, a)
+
+		err = db.QueryRow("select null::bigint[]").Scan(m.SQLScanner(&a))
+		require.NoError(t, err)
+		assert.Equal(t, pgtype.Array[int64]{Elements: nil, Dims: nil, Valid: false}, a)
+	})
+}
+
+func TestConnQueryScanRange(t *testing.T) {
+	testWithAllQueryExecModes(t, func(t *testing.T, db *sql.DB) {
+		skipCockroachDB(t, db, "Server does not support int4range")
+
+		m := pgtype.NewMap()
+
+		var r pgtype.Range[pgtype.Int4]
+		err := db.QueryRow("select int4range(1, 5)").Scan(m.SQLScanner(&r))
+		require.NoError(t, err)
+		assert.Equal(
+			t,
+			pgtype.Range[pgtype.Int4]{
+				Lower:     pgtype.Int4{Int32: 1, Valid: true},
+				Upper:     pgtype.Int4{Int32: 5, Valid: true},
+				LowerType: pgtype.Inclusive,
+				UpperType: pgtype.Exclusive,
+				Valid:     true,
+			},
+			r)
+	})
+}
+
 // Test type that pgx would handle natively in binary, but since it is not a
 // database/sql native type should be passed through as a string
 func TestConnQueryRowPgxBinary(t *testing.T) {