Search Topology Components

Types of components in SharePoint 2013 Search Topology:

1. Search Admin Component
2. Index
3. Crawler
4. Content Processor
5. Analytic Processor
6. Query Processor

1)Administration Component:-

The search administration component runs the system processes that are essential to search. This is the component that performs provisioning to add and initialize instances of other all search components.

2) Index:-

The index consists of one or more index partitions, and each can have multiple replicas.

Index partitions: You can divide the index into discrete portions, each holding a separate part of the index. Search index is the aggregation of all index partitions.

These index partitions are stored in a set of files on the disk.
Index replicas: To achieve fault tolerance and redundancy, you can create additional index replicas for each index partition. These index replicas can be distributed over multiple servers.

3)Crawler:-

The Crawl Component crawls the content based on what is specified in the crawl databases.To retrieve information, the crawl component connects to the content sources by invoking the appropriate indexing connector or protocol handler. After retrieving the content, the crawl component passes crawled items to the content processing component.

4)Content Processor:- 

The Content Processing Component processes crawled items passed by the Crawler, and sends these items to the Index. It performs operations such as document parsing and property mapping. It also performs linguistics processing and transforms crawled items into artifacts that are included in the search index.

5)Analytic Processor:-

 The Analytics Processing Component performs both search analytics and usage analytics. This component uses information from these analyses to improve search relevance, create search reports, and generate recommendations and deep links.

6)Query Processor:-

Query Processing Component analyzes and processes search queries and results.

When the query processing component receives a query, it performs linguistic processing first (like word breaking and stemming), then analyzes and further processes the query to optimize precision, recall and relevance. In the end, the processed query will be submitted to the index component.

The index component returns a result set based on the processed query, and the Query Processor in turn processes that result set, before returning it to the search front-end.