Apache Solr Interview Questions

Q. Give a Quick Introduction to Apache Solr?
Apache Solr is the standalone searching platform used to search contents across multiple websites and indexing docs using HTTP and XML. The platform is based on the Java Library named Lucene supporting rich schema specifications and offers flexibility when dealing with various document fields.

Schema generally declares how to index each field, which type of fields are available within a schema, which fields are necessary to define, and which field can be used as a primary key for the database. The platform has an in-built extensive search plug-in API to perform custom search operations.

Q. Mention the Popular Features of the Apache Solr Platform?
This is a scalable platform that offers maximum performance with real-time index facilities.
It is based on standardized open interfaces like JSON, XML, and HTTP.
Flexible faceting, advanced, and adaptable search behavior that can be customized based on your needs. Faceting is the arrangement of search results based on real-time indexing of document fields.

Q. Do you know about Apache Lucene?
Apache Lucene is an open-source, free, and high-performance Java Library that facilitates full-text custom search across multiple websites and various document fields including PDF, excel, word, HTML files, etc.

Q. Explain the Request handler in Apache Solr?
Every time a search is performed by the user then the search query is handled by the request handler. It will check the logic necessary to follow to execute any search query. Apache Solr contains multiple request handlers for different types of document fields as per the requirements.

Q. What are the Pros and Cons of Lucene/Standard Query Parser?
Lucene parser has a robust syntax and enables users to perform accurate searches for each of the queries whether it is simple or complex. However, it is not easy to learn the syntax for Lucene Parser so it is vulnerable to errors and only expert programmers can write code for the parser.

Q. What are Necessary Details Included for “Field type” in Apache Solr?
Every time you create a new field in Apache Solr, it should be given a proper Field name, define the field attributes, an implementation class, and given a brief field description.

Q. Define the Concept of Faceting in Apache Solr?
Faceting is the arrangement of search results based on real-time indexing of document fields. With the flexible and advanced Faceting scheme, search results become more accurate and smoother even for complex queries.

Q. Explain the Concept of Dynamic Fields in Solr?
In case, users forgot to define some necessary fields then dynamic fields are just the perfect choice to consider. You can create multiple dynamic fields together and they are highly flexible in indexing fields that are not explicitly defined in the schema.

Q. Define Field Analyzer for the Apache Solr?
The task of the field analyzer is to check the field text and generate a token stream for the same. The input text is analyzed deeply and a custom search is performed as defined by the users. Keep in mind that each field analyzer has one tokenizer only.

Q. Define Tokenizer and its Usage in Apache Solr?
The use of a tokenizer is to divide a stream of text into token series where the token is taken as a subsequence of character in the text. Each newly created token will be passed through filters to add, remove or update the particular token.

Q. Is There Any Process to Copy Data from One Field to Another?
Yes, this is easy with Apache Solr where you can use copying fields to copy data among fields. You just have to make sure that the syntax of the platform has been used correctly at the right time.

Q. Define the Phonetic Filters in Solr?
Phonetic filters are the special filters in Solr that are used to create tokens with the help of phonetic encoding algorithms.

Q. What is Solr Cloud?
Solr has unlimited capabilities to perform fault-tolerant accurate searches that enable users to set up huge clusters of Solr servers. These capabilities are served with the SolrCloud in Apache Solr.

Q. Define the Copying Field in Apache Solr?
The copying field is used to populate fields where data is usually copied or written the same as earlier fields. Make sure that syntax has been used correctly otherwise it may show errors.

Q. Define the Highlighting in Apache Solr?
Here, documents will be fragmented to match the query response of the users, and search results become more accurate when the query is performed on small sections instead of the whole document. Solr has a variety of highlighting utilities that help to make solid control over different fields. The different utilities are used by Request Handlers and they are used again by Apache Lucene Parser or Standard query parser to process a series of token or fragmented documents.

Q. Why are Documents Fragmented into Sections During Query Execution?
This is necessary to divide any document into small sections to perform full-text searching more accurately and precisely. If a search will be performed on the whole document then there are chances that the final output may be disappointed or not as per your expectations.

Q. What is Shard?

In distributed environment, the data is partitioned between multiple Solr instances, where each chunk of that data can be called as a Shard. It contains a subset of the whole index.

Q. What is zookeeper in Solr cloud?

Zookeeper is an Apache project that Solr Cloud uses for centralized configuration, coordination, to manage the cluster and to elect a leader.

Q What is Replica in Solr cloud?

In Solr Core, a copy of shard that runs in a node is known as a replica.

Q. What is Leader in Solr cloud?

Leader is also a replica of shard, which distributes the requests of the Solr Cloud to the remaining replicas.

Q. What is collection in Solr cloud?

A cluster has a logical index that is known as a collection.

Q. What is node in Solr cloud?

In Solr cloud, each single instance of Solr is regarded as a node.

Q. Which are the main configuration files in Apache Solr?

Following are the main configuration files in Apache Solr:

Solr.xml – This file is in $SOLR_HOME directory and contains Solr Cloud related information.
Schema.xml – It contains the whole schema.
Solrconfig.xml – It contains the definitions and core-specific configurations related to request handling and response formatting.
Core.properties – This file contains the configurations specific to the core.

Q. How to start Solr using command prompt?

Following commands need to be used to start Solr:

[[email protected] ~]$ cd

[[email protected] ~]$ cd Solr/

[[email protected] Solr]$ cd bin/

[[email protected] bin]$ ./Solr start

Q. What is a Tokenizer in ElasticSearch ?

A tokenizer receives a stream of characters, breaks it up into individual tokens (usually individual words), and outputs a stream of tokens. Inverted indexes are created and updates using these token values by recording the order or position of each term and the start and end character offsets of the original word which the term represents.

An analyzer must have exactly one Tokenizer.

Q. What is the use of field type?

Field type defines how Solr would interpret data in a field and how that field can be queried.

Q. What all information is specified in field type?

A field type includes four types of information: Name of field type Field attributes An implementation class name If the field type is Text Field, a description of the field analysis for the field type.

Q. What is Field Analyzer?

Working with textual data in Solr, Field Analyzer reviews and checks the filed text and generates a token stream. The pre-process of analyzing of the input text is performed at the time of searching or indexing and at query time. Most Solr applications use Custom Analyzers defined by users. Remember, each Analyzer has only one Tokenizer. You can define an analyzer in the application using the below syntax:

Q. What is copying field?

It is used to describe how to populate fields with data copied from another field.

Q. Name different types of highlighters?

There are 3 highlighters in Solr:

  • Standard Highlighter: provides precise matches even for advanced query parsers.
  • Fast Vector Highlighter: Though less advanced than Standard Highlighter, it works better for more languages and supports Unicode break iterators.
  • Postings Highlighter: Much more precise, efficient and compact than the above vector one but inappropriate for a more number of query terms

Q. What is the use of stats.field?

It is used to generate statistics over the results of arbitrary numeric functions.

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