The converting of bucket to string was fixed.

vmugultyanov · vlamug · commit 5a5fd6a4122e · 2017-07-19T18:14:34.000+03:00
Now the precision is fully used.
diff --git a/plugins/aggregators/histogram/histogram.go b/plugins/aggregators/histogram/histogram.go
@@ -142,7 +142,7 @@ func (h *HistogramAggregator) Push(acc telegraf.Accumulator) {
 
 			for index, bucket := range buckets {
 				count += counts[index]
-				addFields(acc, aggregate, field, strconv.FormatFloat(bucket, 'f', 1, 64), count)
+				addFields(acc, aggregate, field, strconv.FormatFloat(bucket, 'f', -1, 64), count)
 			}
 
 			// the adding a value to the infinitive bucket

Original file line number	Diff line number	Diff line change
`@@ -142,7 +142,7 @@ func (h *HistogramAggregator) Push(acc telegraf.Accumulator) {`
`142`	`142`
`143`	`143`	`for index, bucket := range buckets {`
`144`	`144`	`count += counts[index]`
`145`		`- addFields(acc, aggregate, field, strconv.FormatFloat(bucket, 'f', 1, 64), count)`
	`145`	`+ addFields(acc, aggregate, field, strconv.FormatFloat(bucket, 'f', -1, 64), count)`
`146`	`146`	`}`
`147`	`147`
`148`	`148`	`// the adding a value to the infinitive bucket`