1Z0-1127-25 Practice Question: Building LLM Applications with RAG and Vector Search
A manufacturing company uses OCI OpenSearch to build a RAG application that retrieves procedural documents. After deployment, queries often return outdated procedures even though the vector index was refreshed. What is the most likely cause?
⚠ Common exam trap
Watch out — candidates often assume 'refreshing the vector index' automatically synchronizes it with document updates, but in practice, vector indexes require explicit re-embedding and re-indexing, which is often overlooked in RAG architectures.
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
✓
The full-text search index is not synchronized with the vector index after updates.
In a RAG application using OCI OpenSearch, the vector index and full-text search index are separate. When procedural documents are updated, the full-text search index may reflect changes immediately, but the vector index requires explicit re-indexing or synchronization to update embeddings. If the vector index is not refreshed after updates, queries can still retrieve outdated vector representations, leading to outdated results despite the index being refreshed.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
The embedding model was fine-tuned on outdated data.
Why it's wrong here
The model itself doesn't retrieve outdated documents; it embeds whatever is in the index.
- ✓
The full-text search index is not synchronized with the vector index after updates.
Why this is correct
Outdated procedures remain in the text index if not reindexed.
- ✗
The BM25 scoring algorithm prioritizes older documents due to term frequency.
Why it's wrong here
BM25 doesn't inherently prioritize age.
- ✗
The chunk overlap percentage is too high, causing duplicate context.
Why it's wrong here
Chunk overlap affects duplication, not freshness.
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