MarkLogic Interview Questions and Answers

Q1. What is the need of NoSql databases?

Ans

When compared to relational databases, NoSQL databases are often more scalable and provide superior performance. In addition, the flexibility and ease of use of their data models can speed development in comparison to the relational model, especially in the cloud computing environment.

Q2. Why MarkLogic?

Ans

MarkLogic is not only a NoSQL database, it's the only enterprise NoSQL database. This means that it comes with all of the features that traditional databases have—features that enterprises need. MarkLogic Server is designed to securely store and manage a variety of data to run transactional, operational, and analytical applications. 

Q3. What is cluster in MarkLogic?

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The cluster has multiple machines (hosts), each running an instance of MarkLogic Server. Each host in a cluster is sometimes called a node, and each node in the cluster has its own copy of all of the configuration information for the entire cluster.

Q4. What is FLWOR expression?

Ans

FLWOR (pronounced "flower") is an acronym for "For, Let, Where, Order by, Return".

• For - selects a sequence of nodes
• Let - binds a sequence to a variable
• Where - filters the nodes
• Order by - sorts the nodes
• Return - what to return (gets evaluated once for every node)

Q5. What are the indexes in MarkLogic?

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• Word Indexing.
• Phrase Indexing.
• Relationship Indexing.
• Value Indexing.
• Word and Phrase Indexing.

Q6. How is data stored in MarkLogic?

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It uses XML and JSON documents as its data model, and stores the documents within a transactional repository. It indexes the words and values from each of the loaded documents, as well as the document structure.

Q7. What data formats can be loaded into MarkLogic?

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Q8. How do I create a MarkLogic database?

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Q9. What is triple in MarkLogic?

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Each document can contain multiple triples. The setting for the number of triples stored in documents is defined by MarkLogic Server and is not a user configuration. Ingested triples are indexed with the triples index to provide access and the ability to query the triples with SPARQL, XQuery, or a combination of both.

Q10. How can you query triples in MarkLogic?

Ans

You can use the following methods to query triples:

• SPARQL mode in Query Console. 
• XQuery using the semantics functions, and Search API, or a combination of XQuery and SPARQL.
• HTTP via a SPARQL endpoint.

Q11. How can you query RDF dataset in MarkLogic?

Ans

You can query an RDF dataset using any of these SPARQL query forms:

• SELECT Queries - A SPARQL SELECT query returns a solution, which is a set of bindings of variables and values.
• CONSTRUCT Queries - A SPARQL CONSTRUCT query returns triples as a sequence of sem:triple values in an RDF graph. These triples are constructed by substituting variables in a set of triple templates to create new triples from existing triples.
• DESCRIBE Queries - A SPARQL DESCRIBE query returns a sequence of sem:triple values as an RDF graph that describes the resources found.
• ASK Queries - A SPARQL ASK query returns a boolean (true or false) indicating whether a query pattern matches the dataset.

Q12. How to execute a SPARQL Query in Query Console?

Ans

To execute a SPARQL query:

1. In a Web browser, navigate to the Query Console:   

           http://hostname:8000/qconsole
   
   where hostname is the name of your MarkLogic Server host.

2. From the Query Type drop-down list, select SPARQL Query.

   The Query Console supports syntax highlighting for SPARQL keywords.

3. Construct your SPARQL query. See Constructing a SPARQL Query.

   You can add comments prefaced with the hash symbol (#).

4. From the Content Source drop-down list, select the target database.
5. In the control bar below the query window, click Run.

Q13. What is MarkLogic data hub?

 Ans

The MarkLogic Data Hub isan open-source software interface that works to ingest data from multiple sources, harmonize that data, master it, and then search and analyze it. It runs on MarkLogic Server, and together, they provide a unified platform for mission-critical use cases.

Q14. Are binaries searchable in MarkLogic?

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External binaries require special handling at load time because they are not managed by MarkLogic.

Q15. What is needed in order to communicate with a particular database in MarkLogic via the REST API?

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Q16. Which of the following features are available with MarkLogic search?

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• High Performance Full Text Search
• Search APIs
• Support for Multiple Query Styles
• Full XPath Search Support in XQuery
• Lexicon and Range Index-Based APIs
• Alerting API and Built-Ins
• Semantic Searches
• Template Driven Extraction (TDE)
• Where to Find Additional Search Information

Q17. What type of query requires the triple index in MarkLogic?

Ans

Searches with the cts:triple-range-query constructor require the triple index; if the triple index is not configured, then an exception is thrown. The subjects to look up. When multiple values are specified, the query matches if any value matches.

Q18. Which of the following layers are included in MarkLogic architecture?

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The MarkLogic Reference Application Architecture is a three-tier model containing database, middle, and browser tiers.

Q19. Which of these provide a way to load data into a MarkLogic database?

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MarkLogic Server provides many ways to load content into a database including built-in XQuery functions, the REST Client API, and the command-line tool, MarkLogic Content Pump (mlcp).