Golang TableName.Table方法代碼示例

// getTableID retrieves the table ID for the specified table.
func getTableID(p *planner, tn *parser.TableName) (sqlbase.ID, error) {
	if err := tn.QualifyWithDatabase(p.session.Database); err != nil {
		return 0, err
	}

	virtual, err := getVirtualTableDesc(tn)
	if err != nil {
		return 0, err
	}
	if virtual != nil {
		return virtual.GetID(), nil
	}

	dbID, err := p.getDatabaseID(tn.Database())
	if err != nil {
		return 0, err
	}

	nameKey := tableKey{dbID, tn.Table()}
	key := nameKey.Key()
	gr, err := p.txn.Get(key)
	if err != nil {
		return 0, err
	}
	if !gr.Exists() {
		return 0, sqlbase.NewUndefinedTableError(parser.AsString(tn))
	}
	return sqlbase.ID(gr.ValueInt()), nil
}

// expandStar returns the array of column metadata and name
// expressions that correspond to the expansion of a star.
func (src *dataSourceInfo) expandStar(
	v parser.VarName, qvals qvalMap,
) (columns []ResultColumn, exprs []parser.TypedExpr, err error) {
	if len(src.sourceColumns) == 0 {
		return nil, nil, fmt.Errorf("cannot use \"%s\" without a FROM clause", v)
	}

	colSel := func(idx int) {
		col := src.sourceColumns[idx]
		if !col.hidden {
			qval := qvals.getQVal(columnRef{src, idx})
			columns = append(columns, ResultColumn{Name: col.Name, Typ: qval.datum})
			exprs = append(exprs, qval)
		}
	}

	tableName := parser.TableName{}
	if a, ok := v.(*parser.AllColumnsSelector); ok {
		tableName = a.TableName
	}
	if tableName.Table() == "" {
		for i := 0; i < len(src.sourceColumns); i++ {
			colSel(i)
		}
	} else {
		norm := sqlbase.NormalizeTableName(tableName)

		qualifiedTn, err := src.checkDatabaseName(norm)
		if err != nil {
			return nil, nil, err
		}

		colRange, ok := src.sourceAliases[qualifiedTn]
		if !ok {
			return nil, nil, fmt.Errorf("table %q not found", tableName.String())
		}
		for _, i := range colRange {
			colSel(i)
		}
	}

	return columns, exprs, nil
}

// getTableDesc implements the SchemaAccessor interface.
func (p *planner) getTableDesc(tn *parser.TableName) (*sqlbase.TableDescriptor, error) {
	virtual, err := getVirtualTableDesc(tn)
	if err != nil || virtual != nil {
		return virtual, err
	}

	dbDesc, err := p.mustGetDatabaseDesc(tn.Database())
	if err != nil {
		return nil, err
	}

	desc := sqlbase.TableDescriptor{}
	found, err := p.getDescriptor(tableKey{parentID: dbDesc.ID, name: tn.Table()}, &desc)
	if err != nil {
		return nil, err
	}
	if !found {
		return nil, nil
	}
	return &desc, nil
}

// findColumn looks up the column specified by a VarName. The normalized VarName
// is returned.
func (sources multiSourceInfo) findColumn(
	c *parser.ColumnItem,
) (info *dataSourceInfo, colIdx int, err error) {
	if len(c.Selector) > 0 {
		return nil, invalidColIdx, util.UnimplementedWithIssueErrorf(8318, "compound types not supported yet: %q", c)
	}

	colName := sqlbase.NormalizeName(c.ColumnName)
	var tableName parser.TableName
	if c.TableName.Table() != "" {
		tableName = sqlbase.NormalizeTableName(c.TableName)

		tn, err := sources.checkDatabaseName(tableName)
		if err != nil {
			return nil, invalidColIdx, err
		}
		tableName = tn

		// Propagate the discovered database name back to the original VarName.
		// (to clarify the output of e.g. EXPLAIN)
		c.TableName.DatabaseName = tableName.DatabaseName
	}

	colIdx = invalidColIdx
	for _, src := range sources {
		findCol := func(src, info *dataSourceInfo, colIdx int, idx int) (*dataSourceInfo, int, error) {
			col := src.sourceColumns[idx]
			if sqlbase.ReNormalizeName(col.Name) == colName {
				if colIdx != invalidColIdx {
					return nil, invalidColIdx, fmt.Errorf("column reference %q is ambiguous", c)
				}
				info = src
				colIdx = idx
			}
			return info, colIdx, nil
		}

		if tableName.Table() == "" {
			for idx := 0; idx < len(src.sourceColumns); idx++ {
				info, colIdx, err = findCol(src, info, colIdx, idx)
				if err != nil {
					return info, colIdx, err
				}
			}
		} else {
			colRange, ok := src.sourceAliases[tableName]
			if !ok {
				// The data source "src" has no column for table tableName.
				// Try again with the net one.
				continue
			}
			for _, idx := range colRange {
				info, colIdx, err = findCol(src, info, colIdx, idx)
				if err != nil {
					return info, colIdx, err
				}
			}
		}
	}

	if colIdx == invalidColIdx {
		return nil, invalidColIdx, fmt.Errorf("column name %q not found", c)
	}

	return info, colIdx, nil
}

// getTableLease implements the SchemaAccessor interface.
func (p *planner) getTableLease(tn *parser.TableName) (*sqlbase.TableDescriptor, error) {
	if log.V(2) {
		log.Infof(p.ctx(), "planner acquiring lease on table %s", tn)
	}

	isSystemDB := tn.Database() == sqlbase.SystemDB.Name
	isVirtualDB := isVirtualDatabase(tn.Database())
	if isSystemDB || isVirtualDB || testDisableTableLeases {
		// We don't go through the normal lease mechanism for:
		// - system tables. The system.lease and system.descriptor table, in
		//   particular, are problematic because they are used for acquiring
		//   leases itself, creating a chicken&egg problem.
		// - virtual tables. These tables' descriptors are not persisted,
		//   so they cannot be leased. Instead, we simply return the static
		//   descriptor and rely on the immutability privileges set on the
		//   descriptors to cause upper layers to reject mutations statements.
		tbl, err := p.mustGetTableDesc(tn)
		if err != nil {
			return nil, err
		}
		if err := filterTableState(tbl); err != nil {
			return nil, err
		}
		return tbl, nil
	}

	dbID, err := p.getDatabaseID(tn.Database())
	if err != nil {
		return nil, err
	}

	// First, look to see if we already have a lease for this table.
	// This ensures that, once a SQL transaction resolved name N to id X, it will
	// continue to use N to refer to X even if N is renamed during the
	// transaction.
	var lease *LeaseState
	for _, l := range p.leases {
		if sqlbase.ReNormalizeName(l.Name) == sqlbase.NormalizeName(tn.TableName) &&
			l.ParentID == dbID {
			lease = l
			if log.V(2) {
				log.Infof(p.ctx(), "found lease in planner cache for table %q", tn)
			}
			break
		}
	}

	// If we didn't find a lease or the lease is about to expire, acquire one.
	if lease == nil || p.removeLeaseIfExpiring(lease) {
		var err error
		lease, err = p.leaseMgr.AcquireByName(p.txn, dbID, tn.Table())
		if err != nil {
			if err == sqlbase.ErrDescriptorNotFound {
				// Transform the descriptor error into an error that references the
				// table's name.
				return nil, sqlbase.NewUndefinedTableError(tn.String())
			}
			return nil, err
		}
		p.leases = append(p.leases, lease)
		// If the lease we just acquired expires before the txn's deadline, reduce
		// the deadline.
		p.txn.UpdateDeadlineMaybe(hlc.Timestamp{WallTime: lease.Expiration().UnixNano()})
	}
	return &lease.TableDescriptor, nil
}