diff --git a/docs/ingestion/index.md b/docs/ingestion/index.md index edc07ed6682..6d36dd3c77c 100644 --- a/docs/ingestion/index.md +++ b/docs/ingestion/index.md @@ -169,16 +169,18 @@ For an example of how to configure rollup, and of how the feature will modify yo ### Maximizing rollup ratio -You can measure the rollup ratio of a datasource by comparing the number of rows in Druid with the number of ingested -events. The higher this number, the more benefit you are gaining from rollup. One way to do this is with a -[Druid SQL](../querying/sql.md) query like: +You can measure the rollup ratio of a datasource by comparing the number of rows in Druid (`COUNT`) with the number of ingested +events. One way to do this is with a +[Druid SQL](../querying/sql.md) query such as the following, where "count" refers to a `count`-type metric generated at ingestion time: ```sql -SELECT SUM("cnt") / COUNT(*) * 1.0 FROM datasource +SELECT SUM("count") / (COUNT(*) * 1.0) +FROM datasource ``` -In this query, `cnt` should refer to a "count" type metric specified at ingestion time. See -[Counting the number of ingested events](schema-design.md#counting) on the "Schema design" page for more details about +The higher this number is, the more benefit you are gaining from rollup. + +> See [Counting the number of ingested events](schema-design.md#counting) on the "Schema design" page for more details about how counting works when rollup is enabled. Tips for maximizing rollup: