Example #1
0
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
}