Golang Statement.StatementTag方法代碼示例

func (p *planner) prepare(stmt parser.Statement) (planNode, *roachpb.Error) {
	p.prepareOnly = true
	switch n := stmt.(type) {
	case *parser.Delete:
		return p.Delete(n)
	case *parser.Insert:
		return p.Insert(n, false)
	case *parser.Select:
		return p.Select(n)
	case *parser.Show:
		return p.Show(n)
	case *parser.ShowColumns:
		return p.ShowColumns(n)
	case *parser.ShowDatabases:
		return p.ShowDatabases(n)
	case *parser.ShowGrants:
		return p.ShowGrants(n)
	case *parser.ShowIndex:
		return p.ShowIndex(n)
	case *parser.ShowTables:
		return p.ShowTables(n)
	case *parser.Update:
		return p.Update(n)
	default:
		return nil, roachpb.NewUErrorf("prepare statement not supported: %s", stmt.StatementTag())

		// TODO(mjibson): add support for parser.Values.
		// Broken because it conflicts with INSERT's use of VALUES.
	}
}

// the current transaction might have been committed/rolled back when this returns.
func (e *Executor) execStmt(
	stmt parser.Statement, planMaker *planner, autoCommit bool,
) (Result, error) {
	var result Result
	plan, err := planMaker.makePlan(stmt, nil, autoCommit)
	if err != nil {
		return result, err
	}

	if err := plan.Start(); err != nil {
		return result, err
	}

	result.PGTag = stmt.StatementTag()
	result.Type = stmt.StatementType()

	switch result.Type {
	case parser.RowsAffected:
		result.RowsAffected += countRowsAffected(plan)

	case parser.Rows:
		result.Columns = plan.Columns()
		for _, c := range result.Columns {
			if err := checkResultDatum(c.Typ); err != nil {
				return result, err
			}
		}

		// valuesAlloc is used to allocate the backing storage for the
		// ResultRow.Values slices in chunks.
		var valuesAlloc []parser.Datum
		const maxChunkSize = 64 // Arbitrary, could use tuning.
		chunkSize := 4          // Arbitrary as well.

		for plan.Next() {
			// The plan.Values DTuple needs to be copied on each iteration.
			values := plan.Values()

			n := len(values)
			if len(valuesAlloc) < n {
				valuesAlloc = make([]parser.Datum, len(result.Columns)*chunkSize)
				if chunkSize < maxChunkSize {
					chunkSize *= 2
				}
			}
			row := ResultRow{Values: valuesAlloc[:0:n]}
			valuesAlloc = valuesAlloc[n:]

			for _, val := range values {
				if err := checkResultDatum(val); err != nil {
					return result, err
				}
				row.Values = append(row.Values, val)
			}
			result.Rows = append(result.Rows, row)
		}
	}
	return result, plan.Err()
}

// the current transaction might have been committed/rolled back when this returns.
func (e *Executor) execStmt(
	stmt parser.Statement, planMaker *planner,
	timestamp time.Time, autoCommit bool) (Result, *roachpb.Error) {
	var result Result
	plan, pErr := planMaker.makePlan(stmt, autoCommit)
	if pErr != nil {
		return result, pErr
	}

	result.PGTag = stmt.StatementTag()
	result.Type = stmt.StatementType()

	switch result.Type {
	case parser.RowsAffected:
		result.RowsAffected += countRowsAffected(plan)

	case parser.Rows:
		result.Columns = plan.Columns()
		for _, c := range result.Columns {
			if err := checkResultDatum(c.Typ); err != nil {
				return result, roachpb.NewError(err)
			}
		}

		for plan.Next() {
			// The plan.Values DTuple needs to be copied on each iteration.
			values := plan.Values()
			row := ResultRow{Values: make([]parser.Datum, 0, len(values))}
			for _, val := range values {
				if err := checkResultDatum(val); err != nil {
					return result, roachpb.NewError(err)
				}
				row.Values = append(row.Values, val)
			}
			result.Rows = append(result.Rows, row)
		}
	}

	return result, plan.PErr()
}

func (e *Executor) execStmt(stmt parser.Statement, planMaker *planner) (Result, *roachpb.Error) {
	var result Result
	switch stmt.(type) {
	case *parser.BeginTransaction:
		if planMaker.txn != nil {
			return result, roachpb.NewError(errTransactionInProgress)
		}
		// Start a transaction here and not in planMaker to prevent begin
		// transaction from being called within an auto-transaction below.
		planMaker.setTxn(client.NewTxn(e.db), time.Now())
		planMaker.txn.SetDebugName("sql", 0)
	case *parser.CommitTransaction, *parser.RollbackTransaction:
		if planMaker.txn == nil {
			return result, roachpb.NewError(errNoTransactionInProgress)
		} else if planMaker.txn.Proto.Status == roachpb.ABORTED {
			// Reset to allow starting a new transaction.
			planMaker.resetTxn()
			return result, nil
		}
	case *parser.SetTransaction:
		if planMaker.txn == nil {
			return result, roachpb.NewError(errNoTransactionInProgress)
		}
	default:
		if planMaker.txn != nil && planMaker.txn.Proto.Status == roachpb.ABORTED {
			return result, roachpb.NewError(&roachpb.SqlTransactionAbortedError{})
		}
	}

	// Bind all the placeholder variables in the stmt to actual values.
	if err := parser.FillArgs(stmt, &planMaker.params); err != nil {
		return result, roachpb.NewError(err)
	}

	// Create a function which both makes and executes the plan, populating
	// result.
	//
	// TODO(pmattis): Should this be a separate function? Perhaps we should move
	// some of the common code back out into execStmts and have execStmt contain
	// only the body of this closure.
	f := func(timestamp time.Time, autoCommit bool) *roachpb.Error {
		planMaker.evalCtx.StmtTimestamp = parser.DTimestamp{Time: timestamp}
		plan, pErr := planMaker.makePlan(stmt, autoCommit)
		if pErr != nil {
			return pErr
		}

		result.PGTag = stmt.StatementTag()
		result.Type = stmt.StatementType()

		switch result.Type {
		case parser.RowsAffected:
			for plan.Next() {
				result.RowsAffected++
			}

		case parser.Rows:
			result.Columns = plan.Columns()
			for _, c := range result.Columns {
				if err := checkResultDatum(c.Typ); err != nil {
					return err
				}
			}

			for plan.Next() {
				// The plan.Values DTuple needs to be copied on each iteration.
				values := plan.Values()
				row := ResultRow{Values: make([]parser.Datum, 0, len(values))}
				for _, val := range values {
					if err := checkResultDatum(val); err != nil {
						return err
					}
					row.Values = append(row.Values, val)
				}
				result.Rows = append(result.Rows, row)
			}
		}

		return plan.PErr()
	}

	// If there is a pending transaction.
	if planMaker.txn != nil {
		pErr := f(time.Now(), false)
		return result, pErr
	}

	if testingWaitForMetadata {
		// We might need to verify metadata. Lock the system config so that
		// no gossip updates sneak in under us.
		// This lock does not change semantics. Even outside of tests, the
		// planner is initialized with a static systemConfig, so locking
		// the Executor's systemConfig cannot change the semantics of the
		// SQL operation being performed under lock.
		//
		// The case of a multi-request transaction is not handled here,
		// because those transactions outlive the verification callback.
		// This can be addressed when we move to a connection-oriented
		// protocol and server-side transactions.
		e.systemConfigCond.L.Lock()
//.........這裏部分代碼省略.........