--- layout: doc_page title: "Tutorial: Roll-up" --- # Tutorial: Roll-up Apache Druid (incubating) can summarize raw data at ingestion time using a process we refer to as "roll-up". Roll-up is a first-level aggregation operation over a selected set of columns that reduces the size of stored segments. This tutorial will demonstrate the effects of roll-up on an example dataset. For this tutorial, we'll assume you've already downloaded Druid as described in the [single-machine quickstart](index.html) and have it running on your local machine. It will also be helpful to have finished [Tutorial: Loading a file](../tutorials/tutorial-batch.html) and [Tutorial: Querying data](../tutorials/tutorial-query.html). ## Example data For this tutorial, we'll use a small sample of network flow event data, representing packet and byte counts for traffic from a source to a destination IP address that occurred within a particular second. ```json {"timestamp":"2018-01-01T01:01:35Z","srcIP":"1.1.1.1", "dstIP":"2.2.2.2","packets":20,"bytes":9024} {"timestamp":"2018-01-01T01:01:51Z","srcIP":"1.1.1.1", "dstIP":"2.2.2.2","packets":255,"bytes":21133} {"timestamp":"2018-01-01T01:01:59Z","srcIP":"1.1.1.1", "dstIP":"2.2.2.2","packets":11,"bytes":5780} {"timestamp":"2018-01-01T01:02:14Z","srcIP":"1.1.1.1", "dstIP":"2.2.2.2","packets":38,"bytes":6289} {"timestamp":"2018-01-01T01:02:29Z","srcIP":"1.1.1.1", "dstIP":"2.2.2.2","packets":377,"bytes":359971} {"timestamp":"2018-01-01T01:03:29Z","srcIP":"1.1.1.1", "dstIP":"2.2.2.2","packets":49,"bytes":10204} {"timestamp":"2018-01-02T21:33:14Z","srcIP":"7.7.7.7", "dstIP":"8.8.8.8","packets":38,"bytes":6289} {"timestamp":"2018-01-02T21:33:45Z","srcIP":"7.7.7.7", "dstIP":"8.8.8.8","packets":123,"bytes":93999} {"timestamp":"2018-01-02T21:35:45Z","srcIP":"7.7.7.7", "dstIP":"8.8.8.8","packets":12,"bytes":2818} ``` A file containing this sample input data is located at `quickstart/tutorial/rollup-data.json`. We'll ingest this data using the following ingestion task spec, located at `quickstart/tutorial/rollup-index.json`. ```json { "type" : "index", "spec" : { "dataSchema" : { "dataSource" : "rollup-tutorial", "parser" : { "type" : "string", "parseSpec" : { "format" : "json", "dimensionsSpec" : { "dimensions" : [ "srcIP", "dstIP" ] }, "timestampSpec": { "column": "timestamp", "format": "iso" } } }, "metricsSpec" : [ { "type" : "count", "name" : "count" }, { "type" : "longSum", "name" : "packets", "fieldName" : "packets" }, { "type" : "longSum", "name" : "bytes", "fieldName" : "bytes" } ], "granularitySpec" : { "type" : "uniform", "segmentGranularity" : "week", "queryGranularity" : "minute", "intervals" : ["2018-01-01/2018-01-03"], "rollup" : true } }, "ioConfig" : { "type" : "index", "firehose" : { "type" : "local", "baseDir" : "quickstart/tutorial", "filter" : "rollup-data.json" }, "appendToExisting" : false }, "tuningConfig" : { "type" : "index", "maxRowsPerSegment" : 5000000, "maxRowsInMemory" : 25000 } } } ``` Roll-up has been enabled by setting `"rollup" : true` in the `granularitySpec`. Note that we have `srcIP` and `dstIP` defined as dimensions, a longSum metric is defined for the `packets` and `bytes` columns, and the `queryGranularity` has been defined as `minute`. We will see how these definitions are used after we load this data. ## Load the example data From the apache-druid-#{DRUIDVERSION} package root, run the following command: ```bash bin/post-index-task --file quickstart/tutorial/rollup-index.json --url http://localhost:8081 ``` After the script completes, we will query the data. ## Query the example data Let's run `bin/dsql` and issue a `select * from "rollup-tutorial";` query to see what data was ingested. ```bash $ bin/dsql Welcome to dsql, the command-line client for Druid SQL. Type "\h" for help. dsql> select * from "rollup-tutorial"; ┌──────────────────────────┬────────┬───────┬─────────┬─────────┬─────────┐ │ __time │ bytes │ count │ dstIP │ packets │ srcIP │ ├──────────────────────────┼────────┼───────┼─────────┼─────────┼─────────┤ │ 2018-01-01T01:01:00.000Z │ 35937 │ 3 │ 2.2.2.2 │ 286 │ 1.1.1.1 │ │ 2018-01-01T01:02:00.000Z │ 366260 │ 2 │ 2.2.2.2 │ 415 │ 1.1.1.1 │ │ 2018-01-01T01:03:00.000Z │ 10204 │ 1 │ 2.2.2.2 │ 49 │ 1.1.1.1 │ │ 2018-01-02T21:33:00.000Z │ 100288 │ 2 │ 8.8.8.8 │ 161 │ 7.7.7.7 │ │ 2018-01-02T21:35:00.000Z │ 2818 │ 1 │ 8.8.8.8 │ 12 │ 7.7.7.7 │ └──────────────────────────┴────────┴───────┴─────────┴─────────┴─────────┘ Retrieved 5 rows in 1.18s. dsql> ``` Let's look at the three events in the original input data that occurred during `2018-01-01T01:01`: ```json {"timestamp":"2018-01-01T01:01:35Z","srcIP":"1.1.1.1", "dstIP":"2.2.2.2","packets":20,"bytes":9024} {"timestamp":"2018-01-01T01:01:51Z","srcIP":"1.1.1.1", "dstIP":"2.2.2.2","packets":255,"bytes":21133} {"timestamp":"2018-01-01T01:01:59Z","srcIP":"1.1.1.1", "dstIP":"2.2.2.2","packets":11,"bytes":5780} ``` These three rows have been "rolled up" into the following row: ```bash ┌──────────────────────────┬────────┬───────┬─────────┬─────────┬─────────┐ │ __time │ bytes │ count │ dstIP │ packets │ srcIP │ ├──────────────────────────┼────────┼───────┼─────────┼─────────┼─────────┤ │ 2018-01-01T01:01:00.000Z │ 35937 │ 3 │ 2.2.2.2 │ 286 │ 1.1.1.1 │ └──────────────────────────┴────────┴───────┴─────────┴─────────┴─────────┘ ``` The input rows have been grouped by the timestamp and dimension columns `{timestamp, srcIP, dstIP}` with sum aggregations on the metric columns `packets` and `bytes`. Before the grouping occurs, the timestamps of the original input data are bucketed/floored by minute, due to the `"queryGranularity":"minute"` setting in the ingestion spec. Likewise, these two events that occurred during `2018-01-01T01:02` have been rolled up: ```json {"timestamp":"2018-01-01T01:02:14Z","srcIP":"1.1.1.1", "dstIP":"2.2.2.2","packets":38,"bytes":6289} {"timestamp":"2018-01-01T01:02:29Z","srcIP":"1.1.1.1", "dstIP":"2.2.2.2","packets":377,"bytes":359971} ``` ```bash ┌──────────────────────────┬────────┬───────┬─────────┬─────────┬─────────┐ │ __time │ bytes │ count │ dstIP │ packets │ srcIP │ ├──────────────────────────┼────────┼───────┼─────────┼─────────┼─────────┤ │ 2018-01-01T01:02:00.000Z │ 366260 │ 2 │ 2.2.2.2 │ 415 │ 1.1.1.1 │ └──────────────────────────┴────────┴───────┴─────────┴─────────┴─────────┘ ``` For the last event recording traffic between 1.1.1.1 and 2.2.2.2, no roll-up took place, because this was the only event that occurred during `2018-01-01T01:03`: ```json {"timestamp":"2018-01-01T01:03:29Z","srcIP":"1.1.1.1", "dstIP":"2.2.2.2","packets":49,"bytes":10204} ``` ```bash ┌──────────────────────────┬────────┬───────┬─────────┬─────────┬─────────┐ │ __time │ bytes │ count │ dstIP │ packets │ srcIP │ ├──────────────────────────┼────────┼───────┼─────────┼─────────┼─────────┤ │ 2018-01-01T01:03:00.000Z │ 10204 │ 1 │ 2.2.2.2 │ 49 │ 1.1.1.1 │ └──────────────────────────┴────────┴───────┴─────────┴─────────┴─────────┘ ``` Note that the `count` metric shows how many rows in the original input data contributed to the final "rolled up" row.