FAQ

General

When should I use HBase?

See Overview in the Architecture chapter.

Not really. SQL-ish support for HBase via Hive is in development, however Hive is based on MapReduce which is not generally suitable for low-latency requests. See the Data Model section for examples on the HBase client.

How can I find examples of NoSQL/HBase?

See the link to the BigTable paper in Other Information About HBase, as well as the other papers.

What is the history of HBase?

See HBase History.

Why are the cells above 10MB not recommended for HBase?

Large cells don't fit well into HBase's approach to buffering data. First, the large cells bypass the MemStoreLAB when they are written. Then, they cannot be cached in the L2 block cache during read operations. Instead, HBase has to allocate on-heap memory for them each time. This can have a significant impact on the garbage collector within the RegionServer process.

Upgrading

How do I upgrade Maven-managed projects from HBase 0.94 to HBase 0.96+?

In HBase 0.96, the project moved to a modular structure. Adjust your project's dependencies to rely upon the hbase-client module or another module as appropriate, rather than a single JAR. You can model your Maven dependency after one of the following, depending on your targeted version of HBase. See Section 3.5, "Upgrading from 0.94.x to 0.96.x" or Section 3.3, "Upgrading from 0.96.x to 0.98.x" for more information.

Maven Dependency for HBase 0.98

<dependency>
  <groupId>org.apache.hbase</groupId>
  <artifactId>hbase-client</artifactId>
  <version>0.98.5-hadoop2</version>
</dependency>

Maven Dependency for HBase 0.96

<dependency>
  <groupId>org.apache.hbase</groupId>
  <artifactId>hbase-client</artifactId>
  <version>0.96.2-hadoop2</version>
</dependency>

Maven Dependency for HBase 0.94

<dependency>
  <groupId>org.apache.hbase</groupId>
  <artifactId>hbase</artifactId>
  <version>0.94.3</version>
</dependency>

Architecture

How does HBase handle Region-RegionServer assignment and locality?

See Regions.

Configuration

How can I get started with my first cluster?

See Quick Start - Standalone HBase.

Where can I learn about the rest of the configuration options?

See Apache HBase Configuration.

Schema Design / Data Access

Can I change a table's rowkeys?

This is a very common question. You can't. See Immutability of Rowkeys.

What APIs does HBase support?

See Data Model, Client, and Apache HBase External APIs.

MapReduce

How can I use MapReduce with HBase?

See HBase and MapReduce.

Performance and Troubleshooting

How can I improve HBase cluster performance?

See Apache HBase Performance Tuning.

How can I troubleshoot my HBase cluster?

See Troubleshooting and Debugging Apache HBase.

Amazon EC2

I am running HBase on Amazon EC2 and...

EC2 issues are a special case. See Amazon EC2 and Amazon EC2.

Operations

How do I manage my HBase cluster?

See Apache HBase Operational Management.

How do I back up my HBase cluster?

See HBase Backup.

HBase in Action

Where can I find interesting videos and presentations on HBase?

See Other Information About HBase.

FAQ