Apache
/
druid
mirror of https://github.com/apache/druid.git
1
0
Fork 0
Code Issues Packages Projects Releases Wiki Activity

Merge pull request #757 from pdeva/master 

FAQ on changing data granularity
This commit is contained in:
fjy 2014-09-29 15:40:37 -06:00
parent 7cfe86b7bc bc66b42acc
commit e367f76824
1 changed files with 9 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

9
docs/content/Ingestion-FAQ.md
View File

@ -42,6 +42,15 @@ You can check `<BROKER_IP>:<PORT>/druid/v2/datasources/<YOUR_DATASOURCE>?interva
You can use IngestSegmentFirehose with index task to ingest existing druid segments using a new schema and change the name, dimensions, metrics, rollup, etc. of the segment. You can use IngestSegmentFirehose with index task to ingest existing druid segments using a new schema and change the name, dimensions, metrics, rollup, etc. of the segment.
See [Firehose](Firehose.html) for more details on IngestSegmentFirehose. See [Firehose](Firehose.html) for more details on IngestSegmentFirehose.
## How can I change the granularity of existing data in Druid?
In a lot of situations you may want to lower the granularity of older data. Example, any data older than 1 month has only hour level granularity but newer data has minute level granularity.
To do this use the IngestSegmentFirehose and run an indexer task. The IngestSegment firehose will allow you to take in existing segments from Druid and aggregate them and feed them back into druid. It will also allow you to filter the data in those segments while feeding it back in. This means if there are rows you want to delete, you can just filter them away during re-ingestion.
Typically the above will be run as a batch job to say everyday feed in a chunk of data and aggregate it.
## More information ## More information
Getting data into Druid can definitely be difficult for first time users. Please don't hesitate to ask questions in our IRC channel or on our [google groups page](https://groups.google.com/forum/#!forum/druid-development). Getting data into Druid can definitely be difficult for first time users. Please don't hesitate to ask questions in our IRC channel or on our [google groups page](https://groups.google.com/forum/#!forum/druid-development).