| --- |
| id: index |
| title: "Data management" |
| sidebar_label: "Overview" |
| --- |
| |
| <!-- |
| ~ 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. |
| --> |
| |
| Apache Druid stores data [partitioned by time chunk](../design/storage.md) in immutable |
| files called [segments](../design/segments.md). Data management operations involving replacing, or deleting, |
| these segments include: |
| |
| - [Updates](update.md) to existing data. |
| - [Deletion](delete.md) of existing data. |
| - [Schema changes](schema-changes.md) for new and existing data. |
| - [Compaction](compaction.md) and [automatic compaction](automatic-compaction.md), which reindex existing data to |
| optimize storage footprint and performance. |
