Golang SelectQuery.GetWhereCondition方法代码示例

func Filter(query *parser.SelectQuery, series *protocol.Series) (*protocol.Series, error) {
	if query.GetWhereCondition() == nil {
		return series, nil
	}

	columns := map[string]struct{}{}
	if query.GetFromClause().Type == parser.FromClauseInnerJoin {
	outer:
		for t, cs := range query.GetResultColumns() {
			for _, c := range cs {
				// if this is a wildcard select, then drop all columns and
				// just use '*'
				if c == "*" {
					columns = make(map[string]struct{}, 1)
					columns[c] = struct{}{}
					break outer
				}
				columns[t.Name+"."+c] = struct{}{}
			}
		}
	} else {
		for _, cs := range query.GetResultColumns() {
			for _, c := range cs {
				columns[c] = struct{}{}
			}
		}
	}

	points := series.Points
	series.Points = nil
	for _, point := range points {
		ok, err := matches(query.GetWhereCondition(), series.Fields, point)

		if err != nil {
			return nil, err
		}

		if ok {
			filterColumns(columns, series.Fields, point)
			series.Points = append(series.Points, point)
		}
	}

	if _, ok := columns["*"]; !ok {
		newFields := []string{}
		for _, f := range series.Fields {
			if _, ok := columns[f]; !ok {
				continue
			}

			newFields = append(newFields, f)
		}
		series.Fields = newFields
	}
	return series, nil
}

func NewQueryEngine(query *parser.SelectQuery, responseChan chan *protocol.Response) (*QueryEngine, error) {
	limit := query.Limit

	queryEngine := &QueryEngine{
		query:          query,
		where:          query.GetWhereCondition(),
		limiter:        NewLimiter(limit),
		responseChan:   responseChan,
		seriesToPoints: make(map[string]*protocol.Series),
		// stats stuff
		explain:       query.IsExplainQuery(),
		runStartTime:  0,
		runEndTime:    0,
		pointsRead:    0,
		pointsWritten: 0,
		shardId:       0,
		shardLocal:    false, //that really doesn't matter if it is not EXPLAIN query
		duration:      nil,
		seriesStates:  make(map[string]*SeriesState),
	}

	if queryEngine.explain {
		queryEngine.runStartTime = float64(time.Now().UnixNano()) / float64(time.Millisecond)
	}

	yield := func(series *protocol.Series) error {
		var response *protocol.Response

		queryEngine.limiter.calculateLimitAndSlicePoints(series)
		if len(series.Points) == 0 {
			return nil
		}
		if queryEngine.explain {
			//TODO: We may not have to send points, just count them
			queryEngine.pointsWritten += int64(len(series.Points))
		}
		response = &protocol.Response{Type: &queryResponse, Series: series}
		responseChan <- response
		return nil
	}

	var err error
	if query.HasAggregates() {
		err = queryEngine.executeCountQueryWithGroupBy(query, yield)
	} else if containsArithmeticOperators(query) {
		err = queryEngine.executeArithmeticQuery(query, yield)
	} else {
		err = queryEngine.distributeQuery(query, yield)
	}

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

func NewFilteringEngine(query *parser.SelectQuery, processor Processor) *FilteringEngine {
	shouldFilter := query.GetWhereCondition() != nil
	return &FilteringEngine{query, processor, shouldFilter}
}