HPE Ezmeral Data Fabric 6.1.x is In Maintenance and transitions to "End of Maintenance" in June 2024. Please see the latest documentation.

About MapR 6.1
This site contains the main documentation for Version 6.1 of the MapR Converged Data Platform, including installation, configuration, administration, and reference information.
6.1 Installation
This section contains information about installing and upgrading MapR software. It also contains information about how to migrate data and applications from an Apache Hadoop cluster to a MapR cluster.
6.1 MapR Data Platform
MapR Data Platform is the industry-leading data platform for AI and analytics that solves enterprise business needs.
6.1 Administration
This section describes how to manage the nodes and services that make up a cluster.
- Administering Users and Clusters
  Lists topics that help manage a MapR cluster.
- Administering Nodes
  Provides a synopsis of managing nodes in a cluster.
- Administering Volumes
  This section provide information about how to organize and manage data using volumes, a unique feature of MapR clusters.
- Administering Files and Directories
- Administering Tables
  Administration of the MapR Database is done primarily via the command line (maprcli) or with the Managed Control System (MCS). Regardless of whether the MapR Database table is used for binary files or JSON documents, the same types of commands are used with slightly different parameter options. MapR Database administration is associated with tables, columns and column families, and table regions.
  - Managing Tables
    MapR Database supports two types of table: binary tables and JSON tables. This section covers how to create, edit, and delete tables, as well as how to set parameter values, display parameter values, grant permissions and access, replicate tables, and more using the Control System and the CLI.
  - Managing Column Families and Columns
    This section covers overviews of column families in binary tables and JSON tables, how to create column families, alter them, delete them, set permissions on them, and set and display parameter values.
  - Managing Table Replication
    This section contains topics about setting up table replication and administering existing replicas.
  - Managing Secondary Indexes
    Describes how to manage secondary indexes, including adding, deleting, and listing indexes, setting up your cluster for querying, and troubleshooting index usage.
    - Preparing Clusters for Querying using Secondary Indexes on JSON Tables
      Describes the tasks needed to prepare your environment so you can query MapR Database JSON tables using secondary indexes.
    - Adding Secondary Indexes on JSON Tables
      Describes how to add secondary indexes on MapR Database JSON tables.
    - Troubleshooting Secondary Indexes
      Describes how to debug and troubleshoot usage of secondary indexes.
      - Determining the Query Execution Path for OJAI Queries
        You can determine whether an OJAI query directly accesses MapR Database JSON or leverages the OJAI Distributed Query Service by enabling Java OJAI tracing. Java OJAI tracing logs information that enables you to determine which execution path your queries use.
      - Determining Secondary Index Usage
        This section describes how to determine whether a query is using secondary indexes, depending on the query execution path used.
      - Examining the OJAI Query Plan
        This section describes two ways to access a Java OJAI query plan and provides general information about how to interpret the query plan. You can examine the query plan to determine if the Java OJAI client chooses an appropriate execution path.
      - Identifying Secondary Index Lag
        This section describes the commands you use to determine if updates to a secondary index are lagging.
      - Troubleshooting Secondary Index Encoding Errors
        This section describes how to locate secondary index encoding errors in log files, and then resolve them.
      - Adjusting Memory Settings in the OJAI Distributed Query Service
        This section describes how to verify, through log output, that your OJAI query is running out of memory due to memory limits in the OJAI Distributed Query Service. It then describes how to adjust the memory settings in the service.
    - Listing Secondary Indexes
      Describes how to list information about the secondary indexes created on MapR Database JSON tables.
    - Removing Secondary Indexes on JSON Tables
      Describes how to remove secondary indexes that are no longer needed.
  - Administering Change Data Capture
    This topic covers the Control System and maprcli tools for managing the Change Data Capture (CDC) feature.
  - Indexing MapR Database Binary Tables with Elasticsearch
    As of with MapR 6.0, MapR Database Elastic Search integration capability is deprecated and no longer available in the MapR Database product.
- Administering Streams
- Administering MapR Gateways
  A MapR gateway mediates one-way communication between a source MapR cluster and a destination cluster. You can replicate MapR Database tables (binary and JSON) and MapR Event Store For Apache Kafka streams. MapR gateways also apply updates from JSON tables to their secondary indexes and propagate Change Data Capture (CDC) logs.
- Administering Services
- Monitoring the Cluster
  This section describes how to monitor the health and performance of a MapR cluster.
- Configuring Security
  Describes how to configure security and manage secure clusters.
- Managing Secure Clusters
  Provides procedures that will enable you to use MapR clusters securely.
- Administering the MapR Data Access Gateway
  The MapR Data Access Gateway is a service that acts as a proxy and gateway for translating requests between lightweight client applications and the MapR cluster. This section describes considerations when upgrading the service, how to modify configuration settings, and how to administer and manage the service.
- Planning for High Availability
- Administrator's Reference
  This section contains in-depth reference information for the administrator.
- Troubleshooting Cluster Administration
  Lists the common errors and their solutions.
- Best Practices for Backing Up MapR Information
  Lists the best practices and performance considerations to follow when backing up MapR information.
6.1 Development
This section contains information related to application development for Ezmeral ecosystem components and MapR Data Platform products, including the file system, Database (Key-Value and JSON), and Event Streams.
Other Docs
This section contains release-independent information, including: MapR Installer documentation, Ecosystem release notes, interoperability matrices, security vulnerabilities, and links to other MapR version documentation.
Glossary
Definitions for commonly used terms in MapR Converged Data Platform environments.

Determining Secondary Index Usage

This section describes how to determine whether a query is using secondary indexes, depending on the query execution path used.

Determine whether your query uses the OJAI Distributed Query Service by following the steps outlined at Determining the Query Execution Path for OJAI Queries. The following sections describe next steps depending on the execution path.

Simple OJAI Queries

Using the tracing described at Determining the Query Execution Path for OJAI Queries, you will see the following in the log output:

2017-07-17 17:35:59 TRACE MapRDBTableImplHelper:703 - Scan on Index: 
'testIndex', Primary Table is: '/tmp/testTable', Index Scan QueryCondition: '((field < {"$numberLong":101}))', 
Index Scan startRow: '\x0FZ', Index Scan stopRow: '\x0F\x89\xCA\x80\x00'

The "Scan on Index", highlighted in bold, indicates OJAI used a secondary index to process the query.

Queries Requiring the OJAI Distributed Query Service

The tracing output described at Determining the Query Execution Path for OJAI Queries contains a queryId, highlighted in bold:

2017-07-17 18:51:14 DEBUG DrillDocumentStream:120 - DocumentResultsListener[1].queryIdArrived(queryId = 2692966d-0888-96e2-fa09-0d9befcd3173 , 
sql string = select t.`$$ENC00NQYF6YJUL5UW45AAL5UWI`,t.`$$document` from dfs.`/tmp/testTable` t where (t.`l0_a4_int` = -92) order by t.`l0_a4_int` ASC,t.`_id` DESC)

Use this queryId to retrieve more information through the Drill Web Console, including the query plan selected by the OJAI Distributed Query Service. See Query Profile for details.