R

range index

MarkLogic. MarkLogic Server maintains a universal index for every database to rapidly search the text, structure, and combinations of the text and structure that are found within collections of XML and JSON documents. Queries against these documents may include search conditions based on inequalities (for example, price < 100.00 or date ? thisQtr) XML and JSON documents can incorporate numeric or date information. Specifying range indexes for these elements, attributes, and/or JSON properties will substantially accelerate the evaluation of these queries. See Range Indexes and Lexicons in Administrate MarkLogic Server for more information.

RDF (Resource Description Framework)

Semantics. RDF is an abstract data model used to represent facts and relationships, made up of Subject, Predicate, and Object as a triple. It can be serialized as Terse RDF Triple Language (Turtle), Notation 3 (N3), RDF/XML. RDF is a W3C specification with a defined vocabulary. See the W3C specification.

RDF graph

Semantics. See graph.

RDF triple

Semantics. An RDF statement made up of a Subject, Predicate, and Object. Each triple represents a single fact or relationship.

RDF Triple Store

Semantics. A storage tool for the persistent storage, indexing, and query access to RDF graphs (triples). See triple store.

RDFS (Resource Description Framework Schema)

Semantics. A set of vocabularies, rules about structure and data modeling. In RDF, the RDFS specification lets you describe classes, properties, and metadata about those classes and properties. These rules enable you to infer new facts about your data from the schema. See ruleset.

RDF/XML

Semantics. A serialized format for expressing data in the Resource Description Framework Schema (RDFS) data model with the syntax similar to SPARQL. RDF represents information as a triple consisting of Subject, Predicate, and Object. Notation 3 (N3) and Terse RDF Triple Language (Turtle) are other serializations for RDF.

readers/writers locks

Database. A set of read and write locks that lock documents for reading and update at the time the documents are accessed. MarkLogic Server uses readers/writers locks during update statements. Because update transactions only obtain locks as needed, update statements always see the latest version of a document. The view is still consistent for any given document from the time the document is locked. Once a document is locked, any update statements in other transactions wait for the lock to be released before updating the document. For more details, see Update Transactions: Readers/Writers Locks in Develop Server-Side Applications.

Rebalancer

Database. MarkLogic includes a database rebalancing mechanism that enables it to evenly distribute content among the database forests.

A database rebalancer consists of two parts: an assignment policy for data insert and rebalancing and a rebalancer for data movement. The assignment policies are described in Rebalancer Document Assignment Policies in Administrate MarkLogic Server.

For more information on database rebalancing, see the Database Rebalancing section in Administrate MarkLogic Server.

Redacting Document Content

Redaction is the process of eliminating or obscuring portions of a document as you read it from the database. For example, you can use redaction to eliminate or mask sensitive personal information such as credit card numbers, phone numbers, or email addresses from documents.

Table 2. Common Redaction Terms

reduce task

Hadoop. A task that contributes to the reduce step of a job. A reduce task takes the results of the map tasks as input, produces a set of final result key-value pairs, and stores these results in a database or file system. A reduce task has no dependence on or awareness of other reduce tasks in the same job, so all the reduce tasks can run in parallel.

reducer

Hadoop. Programmatically, a subclass of org.apache.hadoop.mapreduce.Reducer. The reducer aggregates map output into final results during the reduce step of a job. The value portion of an input key-value pair for reduce is a list of all values sharing the same key. One input key-value pair can generate zero, one, or many output pairs.

regex

A generic term for a Regular Expression, a sequence of characters used to form a search pattern, used for string pattern matching.

registered query

MarkLogic. Complex cts:queries that are accessed repeatedly and used as unfiltered cts:query constructors, can be registered with MarkLogic Server for later use. When you register a cts:query expression, a pre-evaluated version of the expression is stored, making subsequent queries using the same expression faster. See Registering cts:query Expressions to Speed Search Performance in Develop Search Applications for more information.

Replica

Flexible Replication. A repository that receives replicated updates from the Master. See Flexible Replication.

replica cluster

Flexible Replication. Shorthand for the cluster that hosts a Replica Database. See Flexible Replication.

Replica Database

Flexible Replication. The database that receives replicated data from the Master Database. See Flexible Replication.

Replica Forest

Flexible Replication. The forest that receives replicated data from the Master Forest. See Flexible Replication.

Replicate

Flexible Replication. To create a copy of a document in another database and to keep that copy in sync (possibly with some time-lag/latency) with the original. See Flexible Replication.

Replication Domain

Flexible Replication. The specification of the set of documents to be replicated. This may be a collection or some other set definition. See Flexible Replication.

Representation

MarkLogic. A view of a resource in a particular format, such as XML, HTML, or JSON.

request

MarkLogic. Any invocation of a program, whether through an app server, through a task server, or through any other means. In addition, certain client calls to app servers (for example, loading an XML document through XCC, downloading an image through HTTP, or locking a document through WebDAV) are also requests. The value of requests is normally 1, but it can be greater than 1 in some situations such as when error handler is set for the specified app server, or when pre-commit triggers are used for the request.

resource

Client-server model software. The asset, data, function, or service that a client requests from a server.

resource (REST)

MarkLogic. An abstraction of a MarkLogic REST API service, as presented by the REST architecture.

Resource Address

MarkLogic. A URL that identifies a MarkLogic Server resource. Resource addresses are described in Resource addresses in Monitor MarkLogic Server and in Understanding REST Resources in Develop Using the REST API.

resource path

MarkLogic. A URL sent to MarkLogic Server to return monitoring information for an object. The resource paths are described in Using the Management API in Monitor MarkLogic Server.

resource server

Client-server model software. A server that holds resources or services that users may request.

REST (Representational State Transfer)

MarkLogic. An architecture style that, in the context of the MarkLogic REST API or monitoring MarkLogic Server, describes the use of HTTP to make calls between a client application and MarkLogic Server to create, update, delete and query content and metadata in the database

REST API instance

MarkLogic. An instantiation of the MarkLogic REST API against which applications can make RESTful HTTP requests. An instance consists of an HTTP App Server, a URL rewriter, a content database, a modules database, and the modules that implement the API. For details, see Administering REST API Instances in Develop Using the REST API.

restricted XPath

MarkLogic. An extended version of indexable path, with support for more constructs like functionCalls, and with some basic level of customization of the restrictions per feature. See also indexable path.

reverse query

MarkLogic. A reverse query is the opposite of a regular query; it returns all of the queries, that if they were run, would match a document. Reverse queries are use in creating alerts. See Overview of Alerting Applications in MarkLogic Server in Develop Search Applications.

rewriter

HTTP server. A method for declaring the rules by which an incoming HTTP request is “rewritten” to target a different path, environment, and/or capability than the default for the server. This is an XQuery module that interprets the URL of an incoming HTTP request and rewrites it to an internal URL that services the request.

role

Security. A role is a named entity that provides authorization privileges and permissions to other roles or to users. You can assign roles to other roles (which can in turn include assignments to other roles, and so on). Roles are the fundamental building blocks that you use to implement your security policies. See also privilege. For details on roles, see Role-Based Security Model in Secure MarkLogic Server.

rollback

Database. Immediately terminate a transaction and discard all updates made by the transaction. All transactions are automatically rolled back on error. Multi-statement transactions may also be explicitly rolled back using xdmp:rollback, or implicitly rolled back due to timeout or reaching the end of the session without calling .

RPO (Recovery Point Objective)

Database. The amount of data you can afford to lose in the event of a disaster. A low RPO means that you will restore the most data (at the cost of performance) and a high RPO means you will potentially store less data, but with less impact to performance. See lag limit.

ruleset

Semantics. A set of inference rules. In MarkLogic, a ruleset may be built up by importing other rulesets. MarkLogic supports several rulesets that map to a common ontology language or subset (Resource Description Framework Schema (RDFS), OWL-Horst).