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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
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.
Creating, Reading, Updating, and Deleting Documents and Tables with the MapR-DB JSON Java API Library
The basic tasks that you can perform with the API library involve the Admin, Document, DocumentMutation, QueryCondition, Table, and TableDescriptor interfaces.

MapR 5.1 Documentation

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.
    - OJAI Documents
      An OJAI document is a tree of fields. Each field has a type and a value, and also has either a name or an array index. Field names are strings. The root of each document is a map.
    - JSON Tables
      Documents are stored in JSON tables, which are tables in which every row is an OJAI document.
    - Creating, Reading, Updating, and Deleting Documents and Tables with the MapR-DB JSON Java API Library
      The basic tasks that you can perform with the API library involve the Admin, Document, DocumentMutation, QueryCondition, Table, and TableDescriptor interfaces.
      - Creating JSON Tables with the MapR-DB OJAI Java API Library
        Create a JSON table by calling an Admin object's createTable() method, passing as an argument the path that you want to use for the new table.
      - Creating Documents with the MapR-DB JSON Java API Library
        You create and manipulate OJAI documents as Document objects.
      - Querying Documents with the MapR-DB JSON Java API Library
        Use the find() and findById() methods of a Table object to query the documents in the JSON table that the Table object represents.
      - Updating and Deleting Documents and Tables with the MapR-DB JSON Java API Library
        This API comes with a large variety of methods for updating OJAI documents and JSON tables. This section lists examples, provides code samples, and links to sections of the Javadoc, where you can see all of the methods for performing such updates.
    - Listing Tables with the MapR-DB JSON Java API Library
      List the JSON tables that are in a folder by calling an Admin object's listTables() method, passing as an argument the path of the folder.
    - Altering JSON Tables with the MapR-DB OJAI Java API Library
      Change the values of table attributes by using a TableDescriptor object and then passing that object to the Admin interface's altertable() method.
    - Deleting JSON Tables with the MapR-DB OJAI Java API Library
      Delete a JSON table by calling an Admin object's deleteTable() method, passing as an argument the path of the table to delete.
    - Compiling and Running Applications that Access JSON Tables and Documents
      You can compile applications that use the MapR-DB JSON API by using the required JAR file from the MapR Maven repository or from the MapR installation. Run applications with the mapr command.
    - Tuning Parameters for Client Applications That Access MapR-DB JSON Tables
      Though tuning client applications is generally not necessary, MapR does offer tuning parameters to change the behavior of client-side caching.
    - Loading Documents into JSON Tables
      There are three command-line utilities for loading documents into JSON tables: mapr copytable, mapr importtable (which works in conjunction with the mapr exporttable utility), and mapr importJSON
    - MapR-DB JSON MapReduce API Library
      This API library extends the Apache Hadoop MapReduce framework, so that you can write your own MapReduce applications to write data from one JSON table to another.
    - Column Families in JSON Tables
      JSON tables store data in column families, which are collections of fields that are stored together on disk.
    - Granting or Denying Access to Fields with Access-Control Expressions
      By using access-control expressions (ACEs), you can grant or deny access to fields and column families that are in JSON tables.
    - Getting Started with MapR-DB JSON and OJAI
  - MapR-DB as a Wide-Column Database
- 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.

Creating, Reading, Updating, and Deleting Documents and Tables with the MapR-DB JSON Java API Library

The basic tasks that you can perform with the API library involve the Admin, Document, DocumentMutation, QueryCondition, Table, and TableDescriptor interfaces.

`Admin`

Use the methods in this interface to perform these tasks:

Create JSON tables
Alter JSON tables
Delete JSON tables
List JSON tables in a folder
Check whether a JSON table exists

For examples of how to use this interface, see the example code for these tasks:

For a full list of methods, see Admin.

`Document`

Use the methods in this interface to create OJAI documents. You can pass Document objects to methods in the Table interface to add documents to tables, replace documents in tables, and delete documents from tables.

For examples of how to use this interface, see the example code for these methods:

For a full list of methods, see Document.

`DocumentMutation`

Use the methods in this interface to specify changes to make to OJAI documents. You can pass DocumentMutation objects to the Table.checkAndMutate() method or the Table.update() method to apply the changes to documents.

For examples of how to use this interface, see the example code for these methods:

For a full list of methods, see DocumentMutation.

`QueryCondition`

Use the methods in this interface to specify conditions for returning results from queries on tables. See Querying with Conditions for more information.

`Table`

Use the methods in this interface to perform these tasks:

Delete documents from tables
Increment numeric values in documents
Insert documents into tables
Query tables to find documents
Replace documents
Update documents with the changes specified in DocumentMutation objects

For examples of how to use this interface for queries on documents, see Querying Documents with the MapR-DB JSON Java API Library.

See also the example code for these methods:

For a full list of methods, see Table.

`TableDescriptor`

Use the methods in this interface to perform these tasks:

Create tables with non-default values for one or more of their parameters
Alter tables

For examples of how to use this interface, see the example code for these tasks:

For a full list of methods, see TableDescriptor in the Javadoc.