MapR 5.1 is at End of Life (EOL) and no longer supported. Please see the latest documentation. This documentation is not being updated.

5.1 DB & Streams
This section covers the MapR-DB, MapR-Streams, and MapR-Gateways features. Each feature may contain both administrator and developer topics.
- MapR-DB
  - Architecture of MapR-DB
    MapR-DB's architecture gives it a large of advantages over other NoSQL databases.
  - Performance Enhancements for SSD Based MapR-DB Deployments
  - MapR-DB as a Document Database
    MapR-DB supports OJAI documents as a native data store. OJAI documents are stored in a compact binary format, not as plain ASCII text.
  - MapR-DB as a Wide-Column Database
    - Logical Model of MapR-DB Binary Tables
    - Filesystem Operations on MapR-DB Tables
    - Migrating Between Apache HBase Tables and MapR-DB Binary Tables
    - Designing Row Keys for MapR-DB Binary Tables
      A row key identifies a row in a MapR-DB binary table.
    - Designing Column Families for MapR-DB Binary Tables
      Scanning an entire table for matches can be very performance-intensive. Column families enable you to group related sets of data and restrict queries to a defined subset, leading to better performance. When you design a column family, think about what kinds of queries are going to be used the most often, and group your columns accordingly.
    - Configuring Maximum Row Sizes for Binary Tables
      The default maximum row size at installation is 32MB. You can configure this maximum by changing the value of the mfs.db.max.rowsize.kb parameter with the maprcli config save command.
    - Enabling Access to MapR Tables via HBase APIs, hbase shell, and MapReduce Jobs
    - Creating MapR-DB Binary Tables
    - Displaying Table Region Information for MapR-DB Tables
    - Creating Applications That Access MapR-DB Binary Tables
    - Bulk Loading and MapR-DB Binary Tables
    - Replicating MapR-DB Binary Tables
    - Indexing MapR-DB Binary Tables with Elasticsearch
    - Impersonation via the HBase REST Gateway
- MapR Streams
  MapR Streams brings integrated publish/subscribe messaging to the MapR Converged Data Platform.
- MapR Gateways
  A MapR gateway mediates one-way communication between a source MapR cluster and a destination cluster. MapR-DB binary tables and MapR Streams streams can be replicated.

Before You Start

Before migrating your tables to another platform, consider the following points:

Schema Changes. Apache HBase and MapR-DB tables have different limits on the number of column families. If you are migrating to MapR, you may be interested in changing your table's schema to take advantage of the increased availability of column families. Conversely, if you're migrating from MapR-DB tables to Apache, you may need to adjust your schema to reflect the reduced availability of column families.
API Mappings: If you are migrating from Apache HBase to MapR-DB tables, examine your current HBase applications to verify the APIs and HBase shell commands used are fully supported.
Namespace Mapping: If the migration will take place over a period of time, be sure to plan your table namespace mappings in advance to ease the transition.
Implementation Limitations: MapR-DB tables do not support HBase coprocessors. If your existing Apache HBase installation uses coprocessors, plan any necessary modifications in advance. MapR-DB tables support a subset of the regular expressions supported in Apache HBase. Check your existing workflow and HBase applications to verify you are not using unsupported regular expressions.

If you are migrating to MapR-DB tables, be sure to change your Apache HBase client to the MapR client by installing the version of the mapr-hbase package that matches the version of Apache HBase on your source cluster.

See Installing MapR Software for information about MapR installation procedures, including setting up the proper repositories.