Golang QuerySpec.GetGroupByInterval方法代码示例

func (self *ShardData) QueryResponseBufferSize(querySpec *parser.QuerySpec, batchPointSize int) int {
	groupByTime := querySpec.GetGroupByInterval()
	if groupByTime == nil {
		// If the group by time is nil, we shouldn't have to use a buffer since the shards should be queried sequentially.
		// However, set this to something high just to be safe.
		log.Debug("BUFFER SIZE: 1000")
		return 1000
	}

	tickCount := int(self.shardNanoseconds / uint64(*groupByTime))
	if tickCount < 10 {
		tickCount = 100
	} else if tickCount > 1000 {
		// cap this because each response should have up to this number of points in it.
		tickCount = tickCount / batchPointSize

		// but make sure it's at least 1k
		if tickCount < 1000 {
			tickCount = 1000
		}
	}
	columnCount := querySpec.GetGroupByColumnCount()
	if columnCount > 1 {
		// we don't really know the cardinality for any column up front. This is a just a multiplier so we'll see how this goes.
		// each response can have many points, so having a buffer of the ticks * 100 should be safe, but we'll see.
		tickCount = tickCount * 100
	}
	log.Debug("BUFFER SIZE: %d", tickCount)
	return tickCount
}

// Returns true if we can aggregate the data locally per shard,
// i.e. the group by interval lines up with the shard duration and
// there are no joins or merges
func (self *ShardData) ShouldAggregateLocally(querySpec *parser.QuerySpec) bool {
	f := querySpec.GetFromClause()
	if f != nil && (f.Type == parser.FromClauseInnerJoin || f.Type == parser.FromClauseMerge) {
		return false
	}

	groupByInterval := querySpec.GetGroupByInterval()
	if groupByInterval == nil {
		if querySpec.HasAggregates() {
			return false
		}
		return true
	}
	return (self.shardDuration%*groupByInterval == 0) && !querySpec.GroupByIrregularInterval
}

func (self *Coordinator) shouldQuerySequentially(shards cluster.Shards, 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 !shards.ShouldAggregateLocally(querySpec) {
		return true
	}

	for _, shard := range shards {
		bufferSize := shard.QueryResponseBufferSize(querySpec, self.config.StoragePointBatchSize)
		// 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
}