feat(pgsql): enhance data type mapping to support serial types

pkg/readers/pgsql/reader_test.go

@@ -177,20 +177,20 @@ func TestMapDataType(t *testing.T) {
 		udtName  string
 		expected string
 	}{
-		{"integer", "int4", "int"},
-		{"bigint", "int8", "int64"},
-		{"smallint", "int2", "int16"},
-		{"character varying", "varchar", "string"},
-		{"text", "text", "string"},
-		{"boolean", "bool", "bool"},
+		{"integer", "int4", "integer"},
+		{"bigint", "int8", "bigint"},
+		{"smallint", "int2", "smallint"},
+		{"character varying", "varchar", "varchar"},
+		{"text", "text", "text"},
+		{"boolean", "bool", "boolean"},
 		{"timestamp without time zone", "timestamp", "timestamp"},
 		{"timestamp with time zone", "timestamptz", "timestamptz"},
 		{"json", "json", "json"},
 		{"jsonb", "jsonb", "jsonb"},
 		{"uuid", "uuid", "uuid"},
-		{"numeric", "numeric", "decimal"},
-		{"real", "float4", "float32"},
-		{"double precision", "float8", "float64"},
+		{"numeric", "numeric", "numeric"},
+		{"real", "float4", "real"},
+		{"double precision", "float8", "double precision"},
 		{"date", "date", "date"},
 		{"time without time zone", "time", "time"},
 		{"bytea", "bytea", "bytea"},
@@ -199,12 +199,31 @@ func TestMapDataType(t *testing.T) {
 
 	for _, tt := range tests {
 		t.Run(tt.pgType, func(t *testing.T) {
-			result := reader.mapDataType(tt.pgType, tt.udtName)
+			result := reader.mapDataType(tt.pgType, tt.udtName, false)
 			if result != tt.expected {
 				t.Errorf("mapDataType(%s, %s) = %s, expected %s", tt.pgType, tt.udtName, result, tt.expected)
 			}
 		})
 	}
+
+	// Test serial type detection with hasNextval=true
+	serialTests := []struct {
+		pgType   string
+		expected string
+	}{
+		{"integer", "serial"},
+		{"bigint", "bigserial"},
+		{"smallint", "smallserial"},
+	}
+
+	for _, tt := range serialTests {
+		t.Run(tt.pgType+"_with_nextval", func(t *testing.T) {
+			result := reader.mapDataType(tt.pgType, "", true)
+			if result != tt.expected {
+				t.Errorf("mapDataType(%s, '', true) = %s, expected %s", tt.pgType, result, tt.expected)
+			}
+		})
+	}
 }
 
 func TestParseIndexDefinition(t *testing.T) {