Golang TableDescriptor.FindColumnByID方法代碼示例

// makeRowDeleter creates a rowDeleter for the given table.
//
// The returned rowDeleter contains a fetchCols field that defines the
// expectation of which values are passed as values to deleteRow. Any column
// passed in requestedCols will be included in fetchCols.
func makeRowDeleter(
	txn *client.Txn,
	tableDesc *sqlbase.TableDescriptor,
	fkTables tableLookupsByID,
	requestedCols []sqlbase.ColumnDescriptor,
	checkFKs bool,
) (rowDeleter, error) {
	indexes := tableDesc.Indexes
	for _, m := range tableDesc.Mutations {
		if index := m.GetIndex(); index != nil {
			indexes = append(indexes, *index)
		}
	}

	fetchCols := requestedCols[:len(requestedCols):len(requestedCols)]
	fetchColIDtoRowIndex := colIDtoRowIndexFromCols(fetchCols)

	maybeAddCol := func(colID sqlbase.ColumnID) error {
		if _, ok := fetchColIDtoRowIndex[colID]; !ok {
			col, err := tableDesc.FindColumnByID(colID)
			if err != nil {
				return err
			}
			fetchColIDtoRowIndex[col.ID] = len(fetchCols)
			fetchCols = append(fetchCols, *col)
		}
		return nil
	}
	for _, colID := range tableDesc.PrimaryIndex.ColumnIDs {
		if err := maybeAddCol(colID); err != nil {
			return rowDeleter{}, err
		}
	}
	for _, index := range indexes {
		for _, colID := range index.ColumnIDs {
			if err := maybeAddCol(colID); err != nil {
				return rowDeleter{}, err
			}
		}
	}

	rd := rowDeleter{
		helper:               rowHelper{tableDesc: tableDesc, indexes: indexes},
		fetchCols:            fetchCols,
		fetchColIDtoRowIndex: fetchColIDtoRowIndex,
	}
	if checkFKs {
		var err error
		if rd.fks, err = makeFKDeleteHelper(txn, *tableDesc, fkTables, fetchColIDtoRowIndex); err != nil {
			return rowDeleter{}, err
		}
	}

	return rd, nil
}

//.........這裏部分代碼省略.........
	for _, index := range tableDesc.Indexes {
		if needsUpdate(index) {
			indexes = append(indexes, index)
		}
	}

	var deleteOnlyIndex map[int]struct{}
	for _, m := range tableDesc.Mutations {
		if index := m.GetIndex(); index != nil {
			if needsUpdate(*index) {
				indexes = append(indexes, *index)

				switch m.State {
				case sqlbase.DescriptorMutation_DELETE_ONLY:
					if deleteOnlyIndex == nil {
						// Allocate at most once.
						deleteOnlyIndex = make(map[int]struct{}, len(tableDesc.Mutations))
					}
					deleteOnlyIndex[len(indexes)-1] = struct{}{}

				case sqlbase.DescriptorMutation_WRITE_ONLY:
				}
			}
		}
	}

	ru := rowUpdater{
		helper:                rowHelper{tableDesc: tableDesc, indexes: indexes},
		updateCols:            updateCols,
		updateColIDtoRowIndex: updateColIDtoRowIndex,
		deleteOnlyIndex:       deleteOnlyIndex,
		primaryKeyColChange:   primaryKeyColChange,
		marshalled:            make([]roachpb.Value, len(updateCols)),
		newValues:             make([]parser.Datum, len(tableDesc.Columns)+len(tableDesc.Mutations)),
	}

	if primaryKeyColChange {
		// These fields are only used when the primary key is changing.
		var err error
		// When changing the primary key, we delete the old values and reinsert
		// them, so request them all.
		if ru.rd, err = makeRowDeleter(txn, tableDesc, fkTables, tableDesc.Columns, skipFKs); err != nil {
			return rowUpdater{}, err
		}
		ru.fetchCols = ru.rd.fetchCols
		ru.fetchColIDtoRowIndex = colIDtoRowIndexFromCols(ru.fetchCols)
		if ru.ri, err = MakeRowInserter(txn, tableDesc, fkTables, tableDesc.Columns, skipFKs); err != nil {
			return rowUpdater{}, err
		}
	} else {
		ru.fetchCols = requestedCols[:len(requestedCols):len(requestedCols)]
		ru.fetchColIDtoRowIndex = colIDtoRowIndexFromCols(ru.fetchCols)

		maybeAddCol := func(colID sqlbase.ColumnID) error {
			if _, ok := ru.fetchColIDtoRowIndex[colID]; !ok {
				col, err := tableDesc.FindColumnByID(colID)
				if err != nil {
					return err
				}
				ru.fetchColIDtoRowIndex[col.ID] = len(ru.fetchCols)
				ru.fetchCols = append(ru.fetchCols, *col)
			}
			return nil
		}
		for _, colID := range tableDesc.PrimaryIndex.ColumnIDs {
			if err := maybeAddCol(colID); err != nil {
				return rowUpdater{}, err
			}
		}
		for _, fam := range tableDesc.Families {
			familyBeingUpdated := false
			for _, colID := range fam.ColumnIDs {
				if _, ok := ru.updateColIDtoRowIndex[colID]; ok {
					familyBeingUpdated = true
					break
				}
			}
			if familyBeingUpdated {
				for _, colID := range fam.ColumnIDs {
					if err := maybeAddCol(colID); err != nil {
						return rowUpdater{}, err
					}
				}
			}
		}
		for _, index := range indexes {
			for _, colID := range index.ColumnIDs {
				if err := maybeAddCol(colID); err != nil {
					return rowUpdater{}, err
				}
			}
		}
	}

	var err error
	if ru.fks, err = makeFKUpdateHelper(txn, *tableDesc, fkTables, ru.fetchColIDtoRowIndex); err != nil {
		return rowUpdater{}, err
	}
	return ru, nil
}