fix: enforce minimum decimal precision and scale in NewArrowWriter and ColumnsToArrowSchema

Author: flarco

core/dbio/iop/arrow.go

@@ -361,6 +361,13 @@ type ArrowWriter struct {
 }
 
 func NewArrowWriter(w io.Writer, columns Columns) (a *ArrowWriter, err error) {
+
+	// set minimum decimal precision/scale
+	for i, col := range columns {
+		columns[i].DbPrecision = lo.Ternary(col.DbPrecision < env.DdlMinDecLength, int(env.DdlMinDecLength), col.DbPrecision)
+		columns[i].DbScale = lo.Ternary(col.DbScale < env.DdlMinDecScale, env.DdlMinDecScale, col.DbScale)
+	}
+
 	a = &ArrowWriter{
 		columns: columns,
 		mem:     memory.NewGoAllocator(),
@@ -506,8 +513,6 @@ func ColumnsToArrowSchema(columns Columns) *arrow.Schema {
 		case FloatType:
 			arrowType = arrow.PrimitiveTypes.Float64
 		case DecimalType:
-			col.DbPrecision = lo.Ternary(col.DbPrecision < env.DdlMinDecLength, int(env.DdlMinDecLength), col.DbPrecision)
-			col.DbScale = lo.Ternary(col.DbScale < env.DdlMinDecScale, env.DdlMinDecScale, col.DbScale)
 			arrowType = &arrow.Decimal128Type{Precision: int32(col.DbPrecision), Scale: int32(col.DbScale)}
 		case DateType:
 			arrowType = arrow.FixedWidthTypes.Date32