Golang Batch.Del方法代碼示例

// deleteRow adds to the batch the kv operations necessary to delete a table row
// with the given values.
func (rd *rowDeleter) deleteRow(b *client.Batch, values []parser.Datum) error {
	if err := rd.fks.checkAll(values); err != nil {
		return err
	}

	primaryIndexKey, secondaryIndexEntries, err := rd.helper.encodeIndexes(rd.fetchColIDtoRowIndex, values)
	if err != nil {
		return err
	}

	for _, secondaryIndexEntry := range secondaryIndexEntries {
		if log.V(2) {
			log.Infof("Del %s", secondaryIndexEntry.Key)
		}
		b.Del(secondaryIndexEntry.Key)
	}

	// Delete the row.
	rd.startKey = roachpb.Key(primaryIndexKey)
	rd.endKey = roachpb.Key(encoding.EncodeNotNullDescending(primaryIndexKey))
	if log.V(2) {
		log.Infof("DelRange %s - %s", rd.startKey, rd.endKey)
	}
	b.DelRange(&rd.startKey, &rd.endKey, false)
	rd.startKey, rd.endKey = nil, nil

	return nil
}

// RenameDatabase renames the database.
// Privileges: security.RootUser user.
//   Notes: postgres requires superuser, db owner, or "CREATEDB".
//          mysql >= 5.1.23 does not allow database renames.
func (p *planner) RenameDatabase(n *parser.RenameDatabase) (planNode, error) {
	if n.Name == "" || n.NewName == "" {
		return nil, errEmptyDatabaseName
	}

	if p.session.User != security.RootUser {
		return nil, fmt.Errorf("only %s is allowed to rename databases", security.RootUser)
	}

	dbDesc, err := p.getDatabaseDesc(string(n.Name))
	if err != nil {
		return nil, err
	}
	if dbDesc == nil {
		return nil, sqlbase.NewUndefinedDatabaseError(string(n.Name))
	}

	if n.Name == n.NewName {
		// Noop.
		return &emptyNode{}, nil
	}

	// Now update the nameMetadataKey and the descriptor.
	descKey := sqlbase.MakeDescMetadataKey(dbDesc.GetID())
	dbDesc.SetName(string(n.NewName))

	if err := dbDesc.Validate(); err != nil {
		return nil, err
	}

	newKey := databaseKey{string(n.NewName)}.Key()
	oldKey := databaseKey{string(n.Name)}.Key()
	descID := dbDesc.GetID()
	descDesc := sqlbase.WrapDescriptor(dbDesc)

	b := client.Batch{}
	b.CPut(newKey, descID, nil)
	b.Put(descKey, descDesc)
	b.Del(oldKey)

	if err := p.txn.Run(&b); err != nil {
		if _, ok := err.(*roachpb.ConditionFailedError); ok {
			return nil, fmt.Errorf("the new database name %q already exists", string(n.NewName))
		}
		return nil, err
	}

	p.setTestingVerifyMetadata(func(systemConfig config.SystemConfig) error {
		if err := expectDescriptorID(systemConfig, newKey, descID); err != nil {
			return err
		}
		if err := expectDescriptor(systemConfig, descKey, descDesc); err != nil {
			return err
		}
		return expectDeleted(systemConfig, oldKey)
	})

	return &emptyNode{}, nil
}

// flush writes all dirty nodes and the tree to the transaction.
func (tc *treeContext) flush(b *client.Batch) {
	if tc.dirty {
		b.Put(keys.RangeTreeRoot, tc.tree)
	}
	for key, cachedNode := range tc.nodes {
		if cachedNode.dirty {
			if cachedNode.node == nil {
				b.Del(keys.RangeTreeNodeKey(roachpb.RKey(key)))
			} else {
				b.Put(keys.RangeTreeNodeKey(roachpb.RKey(key)), cachedNode.node)
			}
		}
	}
}

// deleteIndexRow adds to the batch the kv operations necessary to delete a
// table row from the given index.
func (rd *rowDeleter) deleteIndexRow(
	ctx context.Context, b *client.Batch, idx *sqlbase.IndexDescriptor, values []parser.Datum,
) error {
	if err := rd.fks.checkAll(values); err != nil {
		return err
	}
	secondaryIndexEntry, err := sqlbase.EncodeSecondaryIndex(
		rd.helper.tableDesc, idx, rd.fetchColIDtoRowIndex, values)
	if err != nil {
		return err
	}
	if log.V(2) {
		log.Infof(ctx, "Del %s", secondaryIndexEntry.Key)
	}
	b.Del(secondaryIndexEntry.Key)
	return nil
}

func delMeta(b *client.Batch, key roachpb.Key, desc *roachpb.RangeDescriptor) {
	b.Del(key)
}

//.........這裏部分代碼省略.........
			// backwards compatible with the original BaseFormatVersion.

			idx, ok := ru.updateColIDtoRowIndex[family.DefaultColumnID]
			if !ok {
				continue
			}

			ru.key = keys.MakeFamilyKey(primaryIndexKey, uint32(family.ID))
			if log.V(2) {
				log.Infof("Put %s -> %v", ru.key, ru.marshalled[idx].PrettyPrint())
			}
			b.Put(&ru.key, &ru.marshalled[idx])
			ru.key = nil

			continue
		}

		ru.key = keys.MakeFamilyKey(primaryIndexKey, uint32(family.ID))
		ru.valueBuf = ru.valueBuf[:0]

		var lastColID sqlbase.ColumnID
		familySortedColumnIDs, ok := ru.helper.sortedColumnFamily(family.ID)
		if !ok {
			panic("invalid family sorted column id map")
		}
		for _, colID := range familySortedColumnIDs {
			if ru.helper.columnInPK(colID) {
				if family.ID != 0 {
					return nil, errors.Errorf("primary index column %d must be in family 0, was %d", colID, family.ID)
				}
				// Skip primary key columns as their values are encoded in the key of
				// each family. Family 0 is guaranteed to exist and acts as a sentinel.
				continue
			}

			idx, ok := ru.fetchColIDtoRowIndex[colID]
			if !ok {
				return nil, errors.Errorf("column %d was expected to be fetched, but wasn't", colID)
			}
			col := ru.fetchCols[idx]

			if ru.newValues[idx].Compare(parser.DNull) == 0 {
				continue
			}

			if lastColID > col.ID {
				panic(fmt.Errorf("cannot write column id %d after %d", col.ID, lastColID))
			}
			colIDDiff := col.ID - lastColID
			lastColID = col.ID
			ru.valueBuf, err = sqlbase.EncodeTableValue(ru.valueBuf, colIDDiff, ru.newValues[idx])
			if err != nil {
				return nil, err
			}
		}

		if family.ID != 0 && len(ru.valueBuf) == 0 {
			// The family might have already existed but every column in it is being
			// set to NULL, so delete it.
			if log.V(2) {
				log.Infof("Del %s", ru.key)
			}

			b.Del(&ru.key)
		} else {
			ru.value.SetTuple(ru.valueBuf)
			if log.V(2) {
				log.Infof("Put %s -> %v", ru.key, ru.value.PrettyPrint())
			}
			b.Put(&ru.key, &ru.value)
		}

		ru.key = nil
	}

	// Update secondary indexes.
	for i, newSecondaryIndexEntry := range newSecondaryIndexEntries {
		secondaryIndexEntry := secondaryIndexEntries[i]
		secondaryKeyChanged := !bytes.Equal(newSecondaryIndexEntry.Key, secondaryIndexEntry.Key)
		if secondaryKeyChanged {
			if err := ru.fks.checkIdx(ru.helper.indexes[i].ID, oldValues, ru.newValues); err != nil {
				return nil, err
			}

			if log.V(2) {
				log.Infof("Del %s", secondaryIndexEntry.Key)
			}
			b.Del(secondaryIndexEntry.Key)
			// Do not update Indexes in the DELETE_ONLY state.
			if _, ok := ru.deleteOnlyIndex[i]; !ok {
				if log.V(2) {
					log.Infof("CPut %s -> %v", newSecondaryIndexEntry.Key, newSecondaryIndexEntry.Value.PrettyPrint())
				}
				b.CPut(newSecondaryIndexEntry.Key, &newSecondaryIndexEntry.Value, nil)
			}
		}
	}

	return ru.newValues, nil
}

// Execute the entire schema change in steps. startBackfillNotification is
// called before the backfill starts; it can be nil.
func (sc SchemaChanger) exec(
	startBackfillNotification func() error,
	oldNameNotInUseNotification func(),
) error {
	// Acquire lease.
	lease, err := sc.AcquireLease()
	if err != nil {
		return err
	}
	needRelease := true
	// Always try to release lease.
	defer func(l *sqlbase.TableDescriptor_SchemaChangeLease) {
		// If the schema changer deleted the descriptor, there's no longer a lease to be
		// released.
		if !needRelease {
			return
		}
		if err := sc.ReleaseLease(*l); err != nil {
			log.Warning(err)
		}
	}(&lease)

	// Increment the version and unset tableDescriptor.UpVersion.
	desc, err := sc.MaybeIncrementVersion()
	if err != nil {
		return err
	}

	if desc.GetTable().Deleted() {
		lease, err = sc.ExtendLease(lease)
		if err != nil {
			return err
		}
		// Wait for everybody to see the version with the deleted bit set. When
		// this returns, nobody has any leases on the table, nor can get new leases,
		// so the table will no longer be modified.
		if err := sc.waitToUpdateLeases(); err != nil {
			return err
		}

		// Truncate the table and delete the descriptor.
		if err := sc.truncateAndDropTable(&lease, desc.GetTable()); err != nil {
			return err
		}
		needRelease = false
		return nil
	}

	if desc.GetTable().Renamed() {
		lease, err = sc.ExtendLease(lease)
		if err != nil {
			return err
		}
		// Wait for everyone to see the version with the new name. When this
		// returns, no new transactions will be using the old name for the table, so
		// the old name can now be re-used (by CREATE).
		if err := sc.waitToUpdateLeases(); err != nil {
			return err
		}

		if oldNameNotInUseNotification != nil {
			oldNameNotInUseNotification()
		}
		// Free up the old name(s).
		err := sc.db.Txn(func(txn *client.Txn) error {
			b := client.Batch{}
			for _, renameDetails := range desc.GetTable().Renames {
				tbKey := tableKey{
					sqlbase.ID(renameDetails.OldParentID), renameDetails.OldName}.Key()
				b.Del(tbKey)
			}
			if err := txn.Run(&b); err != nil {
				return err
			}
			return nil
		})
		if err != nil {
			return err
		}

		// Clean up - clear the descriptor's state.
		_, err = sc.leaseMgr.Publish(sc.tableID, func(desc *sqlbase.TableDescriptor) error {
			desc.Renames = nil
			return nil
		}, nil)
		if err != nil {
			return err
		}
	}

	// Wait for the schema change to propagate to all nodes after this function
	// returns, so that the new schema is live everywhere. This is not needed for
	// correctness but is done to make the UI experience/tests predictable.
	defer func() {
		if err := sc.waitToUpdateLeases(); err != nil {
			log.Warning(err)
		}
	}()
//.........這裏部分代碼省略.........