Golang QuerySpec.SelectQuery方法代码示例

func (self *CoordinatorImpl) shouldQuerySequentially(shards []*cluster.ShardData, querySpec *parser.QuerySpec) bool {
	// if the query isn't a select, then it doesn't matter
	if querySpec.SelectQuery != nil {
		return false
	}

	// if the query is a regex, we can't predic the number of responses
	// we get back
	if querySpec.IsRegex() {
		return true
	}
	groupByClause := querySpec.SelectQuery().GetGroupByClause()
	// if there's no group by clause, then we're returning raw points
	// with some math done on them, thus we can't predict the number of
	// points
	if groupByClause == nil {
		return true
	}
	// if there's a group by clause but no group by interval, we can't
	// predict the cardinality of the columns used in the group by
	// interval, thus we can't predict the number of responses returned
	// from the shard
	if querySpec.GetGroupByInterval() == nil {
		return true
	}
	// if there's a group by time and other columns, then the previous
	// logic holds
	if len(groupByClause.Elems) > 1 {
		return true
	}

	// parallel querying only if we're querying a single series, with
	// group by time only
	return false
}

func (self *Shard) Query(querySpec *parser.QuerySpec, processor cluster.QueryProcessor) error {
	if querySpec.IsListSeriesQuery() {
		return self.executeListSeriesQuery(querySpec, processor)
	} else if querySpec.IsDeleteFromSeriesQuery() {
		return self.executeDeleteQuery(querySpec, processor)
	}

	seriesAndColumns := querySpec.SelectQuery().GetReferencedColumns()

	if !self.hasReadAccess(querySpec) {
		return errors.New("User does not have access to one or more of the series requested.")
	}

	for series, columns := range seriesAndColumns {
		if regex, ok := series.GetCompiledRegex(); ok {
			seriesNames := self.metaStore.GetSeriesForDatabaseAndRegex(querySpec.Database(), regex)
			for _, name := range seriesNames {
				if !querySpec.HasReadAccess(name) {
					continue
				}
				err := self.executeQueryForSeries(querySpec, name, columns, processor)
				if err != nil {
					return err
				}
			}
		} else {
			err := self.executeQueryForSeries(querySpec, series.Name, columns, processor)
			if err != nil {
				return err
			}
		}
	}
	return nil
}

func (self *CoordinatorImpl) getShardsAndProcessor(querySpec *parser.QuerySpec, writer SeriesWriter) ([]*cluster.ShardData, cluster.QueryProcessor, chan bool, error) {
	shards := self.clusterConfiguration.GetShards(querySpec)
	shouldAggregateLocally := self.shouldAggregateLocally(shards, querySpec)

	var err error
	var processor cluster.QueryProcessor

	responseChan := make(chan *protocol.Response)
	seriesClosed := make(chan bool)

	selectQuery := querySpec.SelectQuery()
	if selectQuery != nil {
		if !shouldAggregateLocally {
			// if we should aggregate in the coordinator (i.e. aggregation
			// isn't happening locally at the shard level), create an engine
			processor, err = engine.NewQueryEngine(querySpec.SelectQuery(), responseChan)
		} else {
			// if we have a query with limit, then create an engine, or we can
			// make the passthrough limit aware
			processor = engine.NewPassthroughEngineWithLimit(responseChan, 100, selectQuery.Limit)
		}
	} else if !shouldAggregateLocally {
		processor = engine.NewPassthroughEngine(responseChan, 100)
	}

	if err != nil {
		return nil, nil, nil, err
	}

	if processor == nil {
		return shards, nil, nil, nil
	}

	go func() {
		for {
			response := <-responseChan

			if *response.Type == endStreamResponse || *response.Type == accessDeniedResponse {
				writer.Close()
				seriesClosed <- true
				return
			}
			if !(*response.Type == queryResponse && querySpec.IsExplainQuery()) {
				if response.Series != nil && len(response.Series.Points) > 0 {
					writer.Write(response.Series)
				}
			}
		}
	}()

	return shards, processor, seriesClosed, nil
}

func (self *CoordinatorImpl) checkPermission(user common.User, querySpec *parser.QuerySpec) error {
	// if this isn't a regex query do the permission check here
	fromClause := querySpec.SelectQuery().GetFromClause()

	for _, n := range fromClause.Names {
		if _, ok := n.Name.GetCompiledRegex(); ok {
			break
		} else if name := n.Name.Name; !user.HasReadAccess(name) {
			return fmt.Errorf("User doesn't have read access to %s", name)
		}
	}
	return nil
}

func (self *ShardData) Query(querySpec *parser.QuerySpec, response chan *protocol.Response) error {
	// This is only for queries that are deletes or drops. They need to be sent everywhere as opposed to just the local or one of the remote shards.
	// But this boolean should only be set to true on the server that receives the initial query.
	if querySpec.RunAgainstAllServersInShard {
		if querySpec.IsDeleteFromSeriesQuery() {
			return self.logAndHandleDeleteQuery(querySpec, response)
		} else if querySpec.IsDropSeriesQuery() {
			return self.logAndHandleDropSeriesQuery(querySpec, response)
		}
	}

	if self.localShard != nil {
		var processor QueryProcessor
		if querySpec.IsListSeriesQuery() {
			processor = engine.NewListSeriesEngine(response)
		} else if querySpec.IsDeleteFromSeriesQuery() || querySpec.IsDropSeriesQuery() || querySpec.IsSinglePointQuery() {
			maxDeleteResults := 10000
			processor = engine.NewPassthroughEngine(response, maxDeleteResults)
		} else {
			if self.ShouldAggregateLocally(querySpec) {
				processor = engine.NewQueryEngine(querySpec.SelectQuery(), response)
			} else {
				maxPointsToBufferBeforeSending := 1000
				processor = engine.NewPassthroughEngine(response, maxPointsToBufferBeforeSending)
			}
		}
		err := self.localShard.Query(querySpec, processor)
		processor.Close()
		return err
	}

	healthyServers := make([]*ClusterServer, 0, len(self.clusterServers))
	for _, s := range self.clusterServers {
		if !s.IsUp() {
			continue
		}
		healthyServers = append(healthyServers, s)
	}
	healthyCount := len(healthyServers)
	if healthyCount == 0 {
		message := fmt.Sprintf("No servers up to query shard %d", self.id)
		response <- &protocol.Response{Type: &endStreamResponse, ErrorMessage: &message}
		return errors.New(message)
	}
	randServerIndex := int(time.Now().UnixNano() % int64(healthyCount))
	server := healthyServers[randServerIndex]
	request := self.createRequest(querySpec)

	return server.MakeRequest(request, response)
}

func (self *CoordinatorImpl) shouldQuerySequentially(shards []*cluster.ShardData, querySpec *parser.QuerySpec) bool {
	// if the query isn't a select, then it doesn't matter
	if querySpec.SelectQuery() == nil {
		return false
	}

	// if the query is a regex, we can't predic the number of responses
	// we get back
	if querySpec.IsRegex() {
		return true
	}
	groupByClause := querySpec.SelectQuery().GetGroupByClause()
	// if there's no group by clause, then we're returning raw points
	// with some math done on them, thus we can't predict the number of
	// points
	if groupByClause == nil {
		return true
	}
	// if there's a group by clause but no group by interval, we can't
	// predict the cardinality of the columns used in the group by
	// interval, thus we can't predict the number of responses returned
	// from the shard
	if querySpec.GetGroupByInterval() == nil {
		return true
	}
	// if there's a group by time and other columns, then the previous
	// logic holds
	if len(groupByClause.Elems) > 1 {
		return true
	}

	if !self.shouldAggregateLocally(shards, querySpec) {
		return true
	}

	for _, shard := range shards {
		bufferSize := shard.QueryResponseBufferSize(querySpec, self.config.LevelDbPointBatchSize)
		// if the number of repsonses is too big, do a sequential querying
		if bufferSize > self.config.ClusterMaxResponseBufferSize {
			return true
		}
	}

	// parallel querying only if we're querying a single series, with
	// group by time only
	return false
}

func (self *Shard) fetchSinglePoint(querySpec *parser.QuerySpec, series string, fields []*metastore.Field) (*protocol.Series, error) {
	query := querySpec.SelectQuery()
	fieldCount := len(fields)
	fieldNames := make([]string, 0, fieldCount)
	point := &protocol.Point{Values: make([]*protocol.FieldValue, 0, fieldCount)}
	timestamp := common.TimeToMicroseconds(query.GetStartTime())
	sequenceNumber, err := query.GetSinglePointQuerySequenceNumber()
	if err != nil {
		return nil, err
	}

	timeAndSequenceBuffer := bytes.NewBuffer(make([]byte, 0, 16))
	binary.Write(timeAndSequenceBuffer, binary.BigEndian, self.convertTimestampToUint(&timestamp))
	binary.Write(timeAndSequenceBuffer, binary.BigEndian, sequenceNumber)
	sequenceNumber_uint64 := uint64(sequenceNumber)
	point.SequenceNumber = &sequenceNumber_uint64
	point.SetTimestampInMicroseconds(timestamp)

	timeAndSequenceBytes := timeAndSequenceBuffer.Bytes()
	for _, field := range fields {
		pointKeyBuff := bytes.NewBuffer(make([]byte, 0, 24))
		pointKeyBuff.Write(field.IdAsBytes())
		pointKeyBuff.Write(timeAndSequenceBytes)

		if data, err := self.db.Get(pointKeyBuff.Bytes()); err != nil {
			return nil, err
		} else {
			fieldValue := &protocol.FieldValue{}
			err := proto.Unmarshal(data, fieldValue)
			if err != nil {
				return nil, err
			}
			if data != nil {
				fieldNames = append(fieldNames, field.Name)
				point.Values = append(point.Values, fieldValue)
			}
		}
	}

	result := &protocol.Series{Name: &series, Fields: fieldNames, Points: []*protocol.Point{point}}

	return result, nil
}

func (self *Shard) executeQueryForSeries(querySpec *parser.QuerySpec, seriesName string, columns []string, processor cluster.QueryProcessor) error {
	startTimeBytes := self.byteArrayForTime(querySpec.GetStartTime())
	endTimeBytes := self.byteArrayForTime(querySpec.GetEndTime())

	fields, err := self.getFieldsForSeries(querySpec.Database(), seriesName, columns)
	if err != nil {
		// because a db is distributed across the cluster, it's possible we don't have the series indexed here. ignore
		switch err := err.(type) {
		case FieldLookupError:
			log.Debug("Cannot find fields %v", columns)
			return nil
		default:
			log.Error("Error looking up fields for %s: %s", seriesName, err)
			return fmt.Errorf("Error looking up fields for %s: %s", seriesName, err)
		}
	}

	fieldCount := len(fields)
	rawColumnValues := make([]rawColumnValue, fieldCount, fieldCount)
	query := querySpec.SelectQuery()

	aliases := query.GetTableAliases(seriesName)
	if querySpec.IsSinglePointQuery() {
		series, err := self.fetchSinglePoint(querySpec, seriesName, fields)
		if err != nil {
			log.Error("Error reading a single point: %s", err)
			return err
		}
		if len(series.Points) > 0 {
			processor.YieldPoint(series.Name, series.Fields, series.Points[0])
		}
		return nil
	}

	fieldNames, iterators := self.getIterators(fields, startTimeBytes, endTimeBytes, query.Ascending)
	defer func() {
		for _, it := range iterators {
			it.Close()
		}
	}()

	seriesOutgoing := &protocol.Series{Name: protocol.String(seriesName), Fields: fieldNames, Points: make([]*protocol.Point, 0, self.pointBatchSize)}

	// TODO: clean up, this is super gnarly
	// optimize for the case where we're pulling back only a single column or aggregate
	buffer := bytes.NewBuffer(nil)
	valueBuffer := proto.NewBuffer(nil)
	for {
		isValid := false
		point := &protocol.Point{Values: make([]*protocol.FieldValue, fieldCount, fieldCount)}

		for i, it := range iterators {
			if rawColumnValues[i].value != nil || !it.Valid() {
				if err := it.Error(); err != nil {
					return err
				}
				continue
			}

			key := it.Key()
			if len(key) < 16 {
				continue
			}

			if !isPointInRange(fields[i].Id, startTimeBytes, endTimeBytes, key) {
				continue
			}

			value := it.Value()
			sequenceNumber := key[16:]

			rawTime := key[8:16]
			rawColumnValues[i] = rawColumnValue{time: rawTime, sequence: sequenceNumber, value: value}
		}

		var pointTimeRaw []byte
		var pointSequenceRaw []byte
		// choose the highest (or lowest in case of ascending queries) timestamp
		// and sequence number. that will become the timestamp and sequence of
		// the next point.
		for _, value := range rawColumnValues {
			if value.value == nil {
				continue
			}

			pointTimeRaw, pointSequenceRaw = value.updatePointTimeAndSequence(pointTimeRaw,
				pointSequenceRaw, query.Ascending)
		}

		for i, iterator := range iterators {
			// if the value is nil or doesn't match the point's timestamp and sequence number
			// then skip it
			if rawColumnValues[i].value == nil ||
				!bytes.Equal(rawColumnValues[i].time, pointTimeRaw) ||
				!bytes.Equal(rawColumnValues[i].sequence, pointSequenceRaw) {

				point.Values[i] = &protocol.FieldValue{IsNull: &TRUE}
				continue
			}

//.........这里部分代码省略.........

func (self *ShardData) Query(querySpec *parser.QuerySpec, response chan *p.Response) {
	// This is only for queries that are deletes or drops. They need to be sent everywhere as opposed to just the local or one of the remote shards.
	// But this boolean should only be set to true on the server that receives the initial query.
	if querySpec.RunAgainstAllServersInShard {
		if querySpec.IsDeleteFromSeriesQuery() {
			self.logAndHandleDeleteQuery(querySpec, response)
		} else if querySpec.IsDropSeriesQuery() {
			self.logAndHandleDropSeriesQuery(querySpec, response)
		}
	}

	if self.IsLocal {
		var processor QueryProcessor
		var err error

		if querySpec.IsListSeriesQuery() {
			processor = engine.NewListSeriesEngine(response)
		} else if querySpec.IsDeleteFromSeriesQuery() || querySpec.IsDropSeriesQuery() || querySpec.IsSinglePointQuery() {
			maxDeleteResults := 10000
			processor = engine.NewPassthroughEngine(response, maxDeleteResults)
		} else {
			query := querySpec.SelectQuery()
			if self.ShouldAggregateLocally(querySpec) {
				log.Debug("creating a query engine\n")
				processor, err = engine.NewQueryEngine(query, response)
				if err != nil {
					response <- &p.Response{Type: &endStreamResponse, ErrorMessage: p.String(err.Error())}
					log.Error("Error while creating engine: %s", err)
					return
				}
				processor.SetShardInfo(int(self.Id()), self.IsLocal)
			} else if query.HasAggregates() {
				maxPointsToBufferBeforeSending := 1000
				log.Debug("creating a passthrough engine\n")
				processor = engine.NewPassthroughEngine(response, maxPointsToBufferBeforeSending)
			} else {
				maxPointsToBufferBeforeSending := 1000
				log.Debug("creating a passthrough engine with limit\n")
				processor = engine.NewPassthroughEngineWithLimit(response, maxPointsToBufferBeforeSending, query.Limit)
			}
			processor = engine.NewFilteringEngine(query, processor)
		}
		shard, err := self.store.GetOrCreateShard(self.id)
		if err != nil {
			response <- &p.Response{Type: &endStreamResponse, ErrorMessage: p.String(err.Error())}
			log.Error("Error while getting shards: %s", err)
			return
		}
		defer self.store.ReturnShard(self.id)
		err = shard.Query(querySpec, processor)
		processor.Close()
		if err != nil {
			response <- &p.Response{Type: &endStreamResponse, ErrorMessage: p.String(err.Error())}
		}
		response <- &p.Response{Type: &endStreamResponse}
		return
	}

	healthyServers := make([]*ClusterServer, 0, len(self.clusterServers))
	for _, s := range self.clusterServers {
		if !s.IsUp() {
			continue
		}
		healthyServers = append(healthyServers, s)
	}
	healthyCount := len(healthyServers)
	if healthyCount == 0 {
		message := fmt.Sprintf("No servers up to query shard %d", self.id)
		response <- &p.Response{Type: &endStreamResponse, ErrorMessage: &message}
		log.Error(message)
		return
	}
	randServerIndex := int(time.Now().UnixNano() % int64(healthyCount))
	server := healthyServers[randServerIndex]
	request := self.createRequest(querySpec)

	server.MakeRequest(request, response)
}

func (self *CoordinatorImpl) runQuerySpec(querySpec *parser.QuerySpec, seriesWriter SeriesWriter) error {
	shards := self.clusterConfiguration.GetShards(querySpec)

	shouldAggregateLocally := true
	var processor cluster.QueryProcessor
	var responseChan chan *protocol.Response
	var seriesClosed chan bool
	for _, s := range shards {
		// If the aggregation is done at the shard level, we don't need to
		// do it here at the coordinator level.
		if !s.ShouldAggregateLocally(querySpec) {
			seriesClosed = make(chan bool)
			shouldAggregateLocally = false
			responseChan = make(chan *protocol.Response)

			if querySpec.SelectQuery() != nil {
				processor = engine.NewQueryEngine(querySpec.SelectQuery(), responseChan)
			} else {
				bufferSize := 100
				processor = engine.NewPassthroughEngine(responseChan, bufferSize)
			}
			go func() {
				for {
					res := <-responseChan
					if *res.Type == endStreamResponse || *res.Type == accessDeniedResponse {
						seriesWriter.Close()
						seriesClosed <- true
						return
					}
					if res.Series != nil && len(res.Series.Points) > 0 {
						seriesWriter.Write(res.Series)
					}
				}
			}()
			break
		}
	}

	responses := make([]chan *protocol.Response, 0)
	for _, shard := range shards {
		responseChan := make(chan *protocol.Response, self.config.QueryShardBufferSize)
		go shard.Query(querySpec, responseChan)
		responses = append(responses, responseChan)
	}

	for i, responseChan := range responses {
		log.Debug("READING: shard: ", shards[i].String())
		for {
			response := <-responseChan
			log.Debug("GOT RESPONSE: ", response.Type, response.Series)
			if *response.Type == endStreamResponse || *response.Type == accessDeniedResponse {
				break
			}
			if shouldAggregateLocally {
				log.Debug("WRITING: ", len(response.Series.Points))
				seriesWriter.Write(response.Series)
				log.Debug("WRITING (done)")
				continue
			}

			// if the data wasn't aggregated at the shard level, aggregate
			// the data here
			log.Debug("YIELDING: ", len(response.Series.Points))
			if response.Series != nil {
				for _, p := range response.Series.Points {
					processor.YieldPoint(response.Series.Name, response.Series.Fields, p)
				}
			}
		}
		log.Debug("DONE: shard: ", shards[i].String())
	}
	if !shouldAggregateLocally {
		processor.Close()
		<-seriesClosed
		return nil
	}
	seriesWriter.Close()
	return nil
}