Web / Apache Solr Interview questions
Explain the execution flow of a Solr search request?
A single /select request passes through a defined pipeline of components before a response is returned.
flowchart LR
A[HTTP request] --> B[SearchHandler]
B --> C[Query parser builds Lucene Query]
C --> D[QueryComponent runs search]
D --> E[FacetComponent]
D --> F[HighlightComponent]
D --> G[MoreLikeThisComponent]
E --> H[ResponseBuilder merges results]
F --> H
G --> H
H --> I[Response writer, JSON/XML]
- The SearchHandler receives the request and reads its configured component chain.
- The active query parser (standard, DisMax, eDisMax) converts
qinto a LuceneQuery. - The QueryComponent executes the search against the index (or all shards, if distributed) and collects matching doc IDs.
- Additional components - facets, highlighting, "more like this" - run if requested, each adding data to the response.
- A response writer (JSON by default) serializes everything into the final HTTP response.
Because this is a configurable chain, custom search components can be inserted at any point, which is how features like spell-check suggestions get added to a query without touching core search logic.
Which component first converts the q parameter into an executable Lucene Query?
Why is the search request pipeline built as a configurable component chain?
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