Semantic search with LLMs: Building a better search experience

Bartosz Świątek

Content Writer

  • September 4, 2025

Contents

When your search system can’t understand that a query for “server migration cost” should return a document titled “budgeting for a cloud transition,” you’re relying on outdated, flawed technology and the cost of this inefficiency is tangible – a 2024 survey showed that businesses leveraging semantic search in their internal knowledge bases saw a 34% reduction in time spent by employees searching for information.

This data clearly shows that the blend of semantic search and Large Language Models (LLMs) is fundamentally changing how we retrieve data. This article explores the technical mechanisms and business advantages of this powerful combination, offering a strategic roadmap for enterprises ready to upgrade their information retrieval systems and create a technically superior and business-critical search experience.

 

The evolution of search from keywords to context

For decades, search technology has been defined by a keyword-centric approach, where relevance was determined by the presence and frequency of specific words. This method, while straightforward, is fundamentally flawed.

A keyword search for “server migration cost” might fail to return a document titled “budgeting for a cloud transition,” despite their identical intent. Semantic search directly addresses this by analyzing not just the words, but the underlying meaning and relationships within the text. It leverages Natural Language Processing (NLP) and machine learning models to build a rich, conceptual understanding of both the query and the documents.

This allows the system to accurately match a user’s intent to relevant information, regardless of the specific vocabulary used, effectively transforming a search from a simple lexical operation into a cognitive one.

The role of embeddings in semantic search

At the core of modern semantic search is the concept of a vector embedding. This is a numerical representation of text, where a block of text (from a single word to an entire document) is mapped to a point in a high-dimensional vector space.

Critically, these vectors are positioned based on semantic similarity. Texts with similar meanings, even if they use different words, are located close to each other in this space.

The mechanics of vector embeddings:

The mechanics of vector embeddings table

Leading research and real-world case studies in the field of natural language processing consistently confirm that the use of advanced embedding models fundamentally improves the precision and recall of information retrieval. This direct correlation between technical accuracy and tangible business value is undeniable.

Interested in implementing a semantic search solution in your company? Check out our Pretius AI Semantic Search product and reach out to us at hello@pretius.com (or via the contact form below).

How large language models supercharge semantic search

While embedding models have been around for some time, LLMs have fundamentally changed the game. Their massive scale, trained on a colossal corpus of internet text, and advanced transformer architectures allow them to create embeddings that are far more nuanced and contextually aware.

An LLM’s ability to grasp subtle linguistic cues, understand complex relationships, and even handle ambiguity makes its generated embeddings vastly superior. This synergy transforms the search engine from a simple lookup tool into a powerful, intelligent system capable of understanding and responding to human language in a more human-like way.

A three-step process for enhanced search results

The true value of an LLM in a semantic search model is realized through a refined, multi-stage process that goes far beyond a single search function.

Query expansion

An LLM can take a simple user query and automatically generate a series of semantically rich, related queries.

This process significantly improves recall. Instead of searching only for “Oracle Cloud,” an LLM might expand the query to include “AWS vs. OCI cost comparison,” “Oracle Cloud Infrastructure benefits,” and “migrating database to OCI.” This proactive enrichment of the user’s intent ensures a more comprehensive and accurate search of the knowledge base, anticipating what the user might be looking for.

Re-ranking with an LLM

After an initial vector search retrieves a set of candidate documents, a dedicated re-ranking model takes over. This model, often a smaller, more specialized LLM, performs a deeper, more granular analysis. It compares the user query directly against the full text of each candidate document.

While the initial vector search is highly performant, the re-ranker ensures precision by re-evaluating relevance based on a complete, contextual understanding. For example, a document mentioning “cloud migration” once might be ranked lower than one discussing “cloud migration strategies” in detail, even if both were close in the initial vector space. This two-stage approach—fast retrieval followed by precise re-ranking—is a key to a superior user experience.

Direct answer generation

The final, most impactful step for the user is direct answer generation, often powered by a Retrieval-Augmented Generation (RAG) system. The LLM synthesizes information from the most relevant documents identified in the previous steps to formulate a concise, coherent, and direct answer (it can also be formulated in multiple languages).

This eliminates the need for the user to click through multiple links to find the information they need. By providing a summarized, factual response, the system turns the search engine into an intelligent “answer engine.” For a business audience, this translates into immediate productivity gains and an unmatched user experience.

The business advantages semantic search enables

The technical prowess of semantic search with LLMs translates directly into tangible business benefits:

  • Elevated user experience:  Customers and employees can find information faster and more intuitively. This reduces frustration and decreases support tickets. An IDC study showed that businesses leveraging advanced search technologies in their internal knowledge bases saw a 30-35% increase in productivity, highlighting a direct impact on operational efficiency. (Source)
  • Improved content discoverability: By understanding the true intent behind queries, a business can ensure that valuable content—be it a product guide, a technical manual, or a company policy—is always discoverable, regardless of how the user phrases their search. This maximizes the return on investment in content creation.
  • Actionable insights: The queries themselves become a rich source of data. By analyzing the topics and intents of user queries, a business can gain insights into what information is most sought after and identify gaps in content strategy. This data can inform product development, marketing efforts, and knowledge management initiatives.

Strategic considerations for a semantic search implementation

For enterprises, implementing semantic search systems with LLMs requires careful planning. The business value is clear, but the technical integration and operational costs must be managed.

Key challenges

  • Computational cost: The massive size and complexity of LLMs can lead to high computational costs for training and inference. However, enterprises can mitigate this by carefully evaluating a range of models, including efficient open-source options, and leveraging optimized deployment strategies (on-premise vs. cloud) to find the right balance of performance and cost. Modern infrastructure and strategic model selection make these costs manageable and predictable.
  • Data scalability: Managing and searching millions or billions of embedding vectors efficiently requires dedicated, specialized vector databases. Unlike traditional databases, these are optimized for similarity searches, which is critical for maintaining performance at a large scale. The market offers robust and highly performant vector databases that are specifically designed to handle these massive datasets with ease, ensuring scalability is no longer a bottleneck.
  • Search accuracy and hallucination: LLMs, despite their power, can sometimes generate plausible but factually incorrect information (hallucination). The RAG framework is a critical technical solution to mitigate this risk by grounding answers in factual, retrieved documents. This ensures the generated information is not only coherent but also verifiable. Moreover, comprehensive calibration conducted by an expert team can boost accuracy significantly – for example, our Pretius AI Semantic Search has a 95% accuracy rate when fully configured.

Future trends

  • Multimodal search: The next evolution will allow queries to combine various data types, such as text, images, and audio. For example, while they perform semantic search, a user could upload an image of a device and ask, “How do I fix this?” The system would then use LLMs to understand the visual and linguistic context to provide a relevant, text-based answer.
  • Structured data integration: The fusion of LLM-based search with structured data from sources like knowledge graphs will be crucial. This integration will provide more verifiable, authoritative answers, moving beyond plausible responses to factual, data-driven ones. This is essential for fields like finance, healthcare, and legal services, where accuracy is paramount.

Summary

The convergence of semantic search and LLMs represents a pivotal moment in information retrieval. By moving beyond a simple keyword-matching paradigm, this technology enables a search experience defined by contextual understanding, intent-driven relevance, and direct answer generation.

This shift not only improves the end-user experience but also delivers tangible business value through increased efficiency, better content discoverability, and actionable insights. For businesses navigating a data-rich environment, adopting this advanced search methodology is more than a technical upgrade; it’s a strategic imperative.

Our Pretius AI Semantic Search product offers an enterprise-grade solution to these challenges, providing high accuracy with traceability, role-based access control, and seamless integration with your existing systems. It is designed to eliminate information silos and accelerate decision-making, ensuring your data remains secure within your own infrastructure..

FAQs

What is semantic search and how is it different from keyword-based search? 

A Semantic search engine goes beyond simple keyword matching to understand the user’s intent and the underlying meaning of their query. Unlike traditional search, which relies on exact words, semantic search leverages Natural Language Processing (NLP) to build a conceptual understanding of both the query and the content, delivering more contextually relevant results.

What are the key business benefits of implementing a semantic search solution? 

The main benefits are improved customer satisfaction and increased employee productivity. The article highlights a 30-35% increase in productivity for employees who can find information faster. It also leads to better content discoverability, ensuring valuable assets like product guides or company policies are easily found, which maximizes the return on content creation.

How do Large Language Models (LLMs) enhance the power of semantic search?

Large Language Models (LLMs) fundamentally improve semantic search by generating more nuanced and accurate vector embeddings. Thanks to their advanced architecture, LLMs can expand queries with related terms, re-rank initial search results for greater precision, and generate direct, concise answers from multiple documents, effectively turning a search engine into an intelligent “answer engine.”

Can you explain the three-step process for enhanced search results? 

This multi-stage process ensures both speed and precision.

  1. Query Expansion: The LLM expands a simple query into a series of related searches to improve the comprehensiveness of results.
  2. Re-ranking: A specialized model performs a deeper analysis of the initial search results, re-ordering them based on a more detailed contextual understanding.
  3. Direct Answer Generation: The final step where the LLM synthesizes information from the most relevant documents to provide a direct, summarized answer to the user’s query.

What are the main challenges in implementing a semantic search solution with LLMs? 

Semantic search applications pave the way towards improved customer satisfaction and increased employee productivity. The article highlights a 30-35% increase in productivity for employees who can find information faster. It also leads to better content discoverability, ensuring valuable assets like product guides or company policies are easily found, which maximizes the return on content creation.

Looking for a software development company?

Work with a team that already helped dozens of market leaders. Book a discovery call to see:

  • How our products work
  • How you can save time & costs
  • How we’re different from another solutions

footer-contact-steps

We keep your data safe: ISO certified

We operate in accordance with the ISO 27001 standard, ensuring the highest level of security for your data.
certified dekra 27001
© 2025 Pretius. All right reserved.