mirror of
https://github.com/apache/druid.git
synced 2025-02-07 02:28:19 +00:00
* Various documentation updates. 1) Split out "data management" from "ingestion". Break it into thematic pages. 2) Move "SQL-based ingestion" into the Ingestion category. Adjust content so all conceptual content is in concepts.md and all syntax content is in reference.md. Shorten the known issues page to the most interesting ones. 3) Add SQL-based ingestion to the ingestion method comparison page. Remove the index task, since index_parallel is just as good when maxNumConcurrentSubTasks: 1. 4) Rename various mentions of "Druid console" to "web console". 5) Add additional information to ingestion/partitioning.md. 6) Remove a mention of Tranquility. 7) Remove a note about upgrading to Druid 0.10.1. 8) Remove no-longer-relevant task types from ingestion/tasks.md. 9) Move ingestion/native-batch-firehose.md to the hidden section. It was previously deprecated. 10) Move ingestion/native-batch-simple-task.md to the hidden section. It is still linked in some places, but it isn't very useful compared to index_parallel, so it shouldn't take up space in the sidebar. 11) Make all br tags self-closing. 12) Certain other cosmetic changes. 13) Update to node-sass 7. * make travis use node12 for docs Co-authored-by: Vadim Ogievetsky <vadim@ogievetsky.com>
40 lines
1.8 KiB
Markdown
40 lines
1.8 KiB
Markdown
---
|
|
id: schema-changes
|
|
title: "Schema changes"
|
|
---
|
|
|
|
<!--
|
|
~ Licensed to the Apache Software Foundation (ASF) under one
|
|
~ or more contributor license agreements. See the NOTICE file
|
|
~ distributed with this work for additional information
|
|
~ regarding copyright ownership. The ASF licenses this file
|
|
~ to you under the Apache License, Version 2.0 (the
|
|
~ "License"); you may not use this file except in compliance
|
|
~ with the License. You may obtain a copy of the License at
|
|
~
|
|
~ http://www.apache.org/licenses/LICENSE-2.0
|
|
~
|
|
~ Unless required by applicable law or agreed to in writing,
|
|
~ software distributed under the License is distributed on an
|
|
~ "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
|
|
~ KIND, either express or implied. See the License for the
|
|
~ specific language governing permissions and limitations
|
|
~ under the License.
|
|
-->
|
|
|
|
|
|
## For new data
|
|
|
|
Apache Druid allows you to provide a new schema for new data without the need to update the schema of any existing data.
|
|
It is sufficient to update your supervisor spec, if using [streaming ingestion](../ingestion/index.md#streaming), or to
|
|
provide the new schema the next time you do a [batch ingestion](../ingestion/index.md#batch). This is made possible by
|
|
the fact that each [segment](../design/architecture.md#datasources-and-segments), at the time it is created, stores a
|
|
copy of its own schema. Druid reconciles all of these individual segment schemas automatically at query time.
|
|
|
|
## For existing data
|
|
|
|
Schema changes are sometimes necessary for existing data. For example, you may want to change the type of a column in
|
|
previously-ingested data, or drop a column entirely. Druid handles this using [reindexing](update.md), the same method
|
|
it uses to handle updates of existing data. Reindexing involves rewriting all affected segments and can be a
|
|
time-consuming operation.
|