Function compareColumns

backend/plugin/schema/differ.go:600–637

compareColumns compares columns between two tables.

(engine storepb.Engine, oldTable, newTable *model.TableMetadata)

// compareColumns compares columns between two tables.
func compareColumns(engine storepb.Engine, oldTable, newTable *model.TableMetadata) []*ColumnDiff {
	var changes []*ColumnDiff

	oldColumns := oldTable.GetProto().GetColumns()
	newColumns := newTable.GetProto().GetColumns()

	// Check for dropped columns
	for _, oldCol := range oldColumns {
		if newTable.GetColumn(oldCol.Name) == nil {
			changes = append(changes, &ColumnDiff{
				Action:    MetadataDiffActionDrop,
				OldColumn: oldCol,
			})
		}
	}

	// Check for new and modified columns
	for _, newCol := range newColumns {
		oldColWrapper := oldTable.GetColumn(newCol.Name)
		if oldColWrapper == nil {
			changes = append(changes, &ColumnDiff{
				Action:    MetadataDiffActionCreate,
				NewColumn: newCol,
			})
		} else {
			oldCol := oldColWrapper.GetProto()
			if !columnsEqual(engine, oldCol, newCol) {
				changes = append(changes, &ColumnDiff{
					Action:    MetadataDiffActionAlter,
					OldColumn: oldCol,
					NewColumn: newCol,
				})
			}
		}
	}

	return changes
}

// columnsEqual checks if two columns are equal.
func columnsEqual(engine storepb.Engine, col1, col2 *storepb.ColumnMetadata) bool {