Question 244 of 991

Reduce RAG Latency with Approximate Nearest Neighbor Search

This 1Z0-1127 practice question tests your understanding of building llm applications with rag and vector search. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.

A real-time customer support chatbot uses RAG with OCI Generative AI. The average response time is 5 seconds, which is too slow. The team identifies the vector search as the bottleneck. Which optimization would most reduce latency?

Answer choices

Why each option matters

Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.

Correct answer & explanation

Use approximate nearest neighbor (ANN) search with a lower recall setting

The vector search bottleneck causing high latency is best addressed by reducing the computational cost of the nearest neighbor search. Approximate Nearest Neighbor (ANN) search with a lower recall setting trades a small amount of accuracy for a significant reduction in search time, directly targeting the root cause of the 5-second response time. This optimization is specifically designed for latency-sensitive applications like real-time chatbots.

Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.

Answer analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

  • Use approximate nearest neighbor (ANN) search with a lower recall setting

    Why this is correct

    ANN speeds up search by sacrificing some recall, which can be mitigated by re-ranking.

    Related concept

    Read the scenario before looking for a memorised answer.

  • Increase the number of retrieved documents to 10

    Why it's wrong here

    Retrieving more documents increases post-processing time.

  • Move the vector store to a different region

    Why it's wrong here

    Regional moves can add network latency, not reduce it.

  • Switch to a larger embedding model for better accuracy

    Why it's wrong here

    Larger models increase latency due to higher computational cost.

Common exam traps

Common exam trap: answer the scenario, not the keyword

Oracle often tests the trade-off between accuracy and latency in vector search, where candidates mistakenly think increasing resources (like document count or model size) will improve speed, rather than optimizing the search algorithm itself.

Detailed technical explanation

How to think about this question

ANN algorithms like HNSW (Hierarchical Navigable Small World) or IVF (Inverted File Index) work by partitioning the vector space and only searching a subset of the index. Lowering the recall setting (e.g., reducing the 'ef_search' parameter in HNSW) decreases the number of candidate vectors evaluated per query, directly reducing search time. In a real-world scenario, a chatbot using a 1M-vector index might see latency drop from 5 seconds to under 500ms with a 90% recall setting, which is often acceptable for customer support.

KKey Concepts to Remember

  • Read the scenario before looking for a memorised answer.
  • Find the constraint that changes the correct option.
  • Eliminate answers that are true in general but not in this case.

TExam Day Tips

  • Watch for words such as best, first, most likely and least administrative effort.
  • Review why wrong options are wrong, not only why the correct option is correct.

Key takeaway

Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.

Real-world example

How this comes up in practice

A network engineer at a university connects two campus buildings via a fibre link. Both routers run OSPF, but no adjacency forms — even though both routers can ping each other. The engineer finds one router is in area 0 and the other in area 1. OSPF adjacency requires matching area numbers, hello/dead timers, and network type. IP reachability alone is not enough.

What to study next

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FAQ

Questions learners often ask

What does this 1Z0-1127 question test?

Building LLM Applications with RAG and Vector Search — This question tests Building LLM Applications with RAG and Vector Search — Read the scenario before looking for a memorised answer..

What is the correct answer to this question?

The correct answer is: Use approximate nearest neighbor (ANN) search with a lower recall setting — The vector search bottleneck causing high latency is best addressed by reducing the computational cost of the nearest neighbor search. Approximate Nearest Neighbor (ANN) search with a lower recall setting trades a small amount of accuracy for a significant reduction in search time, directly targeting the root cause of the 5-second response time. This optimization is specifically designed for latency-sensitive applications like real-time chatbots.

What should I do if I get this 1Z0-1127 question wrong?

Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.

What is the key concept behind this question?

Read the scenario before looking for a memorised answer.

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Last reviewed: Jul 4, 2026

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This 1Z0-1127 practice question is part of Courseiva's free Oracle certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the 1Z0-1127 exam.