mirror of https://github.com/apache/druid.git
170 lines
9.3 KiB
Markdown
170 lines
9.3 KiB
Markdown
---
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layout: doc_page
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title: "Tutorial: Updating existing data"
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---
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<!--
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~ Licensed to the Apache Software Foundation (ASF) under one
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~ or more contributor license agreements. See the NOTICE file
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~ regarding copyright ownership. The ASF licenses this file
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# Tutorial: Updating existing data
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This tutorial demonstrates how to update existing data, showing both overwrites and appends.
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For this tutorial, we'll assume you've already downloaded Druid as described in
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the [single-machine quickstart](index.html) and have it running on your local machine.
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It will also be helpful to have finished [Tutorial: Loading a file](../tutorials/tutorial-batch.html), [Tutorial: Querying data](../tutorials/tutorial-query.html), and [Tutorial: Rollup](../tutorials/tutorial-rollup.html).
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## Overwrite
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This section of the tutorial will cover how to overwrite an existing interval of data.
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### Load initial data
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Let's load an initial data set which we will overwrite and append to.
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The spec we'll use for this tutorial is located at `quickstart/tutorial/updates-init-index.json`. This spec creates a datasource called `updates-tutorial` from the `quickstart/tutorial/updates-data.json` input file.
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Let's submit that task:
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```bash
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bin/post-index-task --file quickstart/tutorial/updates-init-index.json
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```
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We have three initial rows containing an "animal" dimension and "number" metric:
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```bash
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dsql> select * from "updates-tutorial";
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┌──────────────────────────┬──────────┬───────┬────────┐
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│ __time │ animal │ count │ number │
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├──────────────────────────┼──────────┼───────┼────────┤
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│ 2018-01-01T01:01:00.000Z │ tiger │ 1 │ 100 │
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│ 2018-01-01T03:01:00.000Z │ aardvark │ 1 │ 42 │
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│ 2018-01-01T03:01:00.000Z │ giraffe │ 1 │ 14124 │
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└──────────────────────────┴──────────┴───────┴────────┘
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Retrieved 3 rows in 1.42s.
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```
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### Overwrite the initial data
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To overwrite this data, we can submit another task for the same interval, but with different input data.
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The `quickstart/tutorial/updates-overwrite-index.json` spec will perform an overwrite on the `updates-tutorial` datasource.
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Note that this task reads input from `quickstart/tutorial/updates-data2.json`, and `appendToExisting` is set to `false` (indicating this is an overwrite).
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Let's submit that task:
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```bash
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bin/post-index-task --file quickstart/tutorial/updates-overwrite-index.json
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```
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When Druid finishes loading the new segment from this overwrite task, the "tiger" row now has the value "lion", the "aardvark" row has a different number, and the "giraffe" row has been replaced. It may take a couple of minutes for the changes to take effect:
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```bash
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dsql> select * from "updates-tutorial";
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┌──────────────────────────┬──────────┬───────┬────────┐
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│ __time │ animal │ count │ number │
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├──────────────────────────┼──────────┼───────┼────────┤
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│ 2018-01-01T01:01:00.000Z │ lion │ 1 │ 100 │
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│ 2018-01-01T03:01:00.000Z │ aardvark │ 1 │ 9999 │
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│ 2018-01-01T04:01:00.000Z │ bear │ 1 │ 111 │
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└──────────────────────────┴──────────┴───────┴────────┘
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Retrieved 3 rows in 0.02s.
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```
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## Combine old data with new data and overwrite
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Let's try appending some new data to the `updates-tutorial` datasource now. We will add the data from `quickstart/tutorial/updates-data3.json`.
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The `quickstart/tutorial/updates-append-index.json` task spec has been configured to read from the existing `updates-tutorial` datasource and the `quickstart/tutorial/updates-data3.json` file. The task will combine data from the two input sources, and then overwrite the original data with the new combined data.
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Let's submit that task:
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```bash
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bin/post-index-task --file quickstart/tutorial/updates-append-index.json
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```
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When Druid finishes loading the new segment from this overwrite task, the new rows will have been added to the datasource. Note that roll-up occurred for the "lion" row:
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```bash
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dsql> select * from "updates-tutorial";
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┌──────────────────────────┬──────────┬───────┬────────┐
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│ __time │ animal │ count │ number │
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├──────────────────────────┼──────────┼───────┼────────┤
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│ 2018-01-01T01:01:00.000Z │ lion │ 2 │ 400 │
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│ 2018-01-01T03:01:00.000Z │ aardvark │ 1 │ 9999 │
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│ 2018-01-01T04:01:00.000Z │ bear │ 1 │ 111 │
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│ 2018-01-01T05:01:00.000Z │ mongoose │ 1 │ 737 │
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│ 2018-01-01T06:01:00.000Z │ snake │ 1 │ 1234 │
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│ 2018-01-01T07:01:00.000Z │ octopus │ 1 │ 115 │
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└──────────────────────────┴──────────┴───────┴────────┘
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Retrieved 6 rows in 0.02s.
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```
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## Append to the data
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Let's try another way of appending data.
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The `quickstart/tutorial/updates-append-index2.json` task spec reads input from `quickstart/tutorial/updates-data4.json` and will append its data to the `updates-tutorial` datasource. Note that `appendToExisting` is set to `true` in this spec.
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Let's submit that task:
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```bash
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bin/post-index-task --file quickstart/tutorial/updates-append-index2.json
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```
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When the new data is loaded, we can see two additional rows after "octopus". Note that the new "bear" row with number 222 has not been rolled up with the existing bear-111 row, because the new data is held in a separate segment.
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```bash
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dsql> select * from "updates-tutorial";
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┌──────────────────────────┬──────────┬───────┬────────┐
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│ __time │ animal │ count │ number │
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├──────────────────────────┼──────────┼───────┼────────┤
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│ 2018-01-01T01:01:00.000Z │ lion │ 2 │ 400 │
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│ 2018-01-01T03:01:00.000Z │ aardvark │ 1 │ 9999 │
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│ 2018-01-01T04:01:00.000Z │ bear │ 1 │ 111 │
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│ 2018-01-01T05:01:00.000Z │ mongoose │ 1 │ 737 │
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│ 2018-01-01T06:01:00.000Z │ snake │ 1 │ 1234 │
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│ 2018-01-01T07:01:00.000Z │ octopus │ 1 │ 115 │
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│ 2018-01-01T04:01:00.000Z │ bear │ 1 │ 222 │
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│ 2018-01-01T09:01:00.000Z │ falcon │ 1 │ 1241 │
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└──────────────────────────┴──────────┴───────┴────────┘
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Retrieved 8 rows in 0.02s.
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```
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If we run a GroupBy query instead of a `select *`, we can see that the "bear" rows will group together at query time:
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```bash
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dsql> select __time, animal, SUM("count"), SUM("number") from "updates-tutorial" group by __time, animal;
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┌──────────────────────────┬──────────┬────────┬────────┐
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│ __time │ animal │ EXPR$2 │ EXPR$3 │
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├──────────────────────────┼──────────┼────────┼────────┤
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│ 2018-01-01T01:01:00.000Z │ lion │ 2 │ 400 │
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│ 2018-01-01T03:01:00.000Z │ aardvark │ 1 │ 9999 │
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│ 2018-01-01T04:01:00.000Z │ bear │ 2 │ 333 │
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│ 2018-01-01T05:01:00.000Z │ mongoose │ 1 │ 737 │
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│ 2018-01-01T06:01:00.000Z │ snake │ 1 │ 1234 │
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│ 2018-01-01T07:01:00.000Z │ octopus │ 1 │ 115 │
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│ 2018-01-01T09:01:00.000Z │ falcon │ 1 │ 1241 │
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└──────────────────────────┴──────────┴────────┴────────┘
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Retrieved 7 rows in 0.23s.
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```
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