Comparison · Comparison
Choosing a vector store for RAG: start with what you already run.
The vector database is rarely what makes or breaks a RAG system — retrieval design is. But the wrong choice adds operational burden or blocks hybrid search and permission filtering. Here’s how the common options compare and how we choose.
By Nythrex EngineeringUpdated 2 min read
Less to operate → More control
Side by side
| pgvector (PostgreSQL) | Azure AI Search | Qdrant | Pinecone | Elasticsearch / OpenSearch | |
|---|---|---|---|---|---|
| Type | Extension to your database | Managed search service | Open-source vector DB; managed cloud available | Managed vector DB | Search engine with vector support |
| Hybrid keyword + vector | Via Postgres full-text + vectors | Built in, with semantic ranking | Supported (sparse + dense) | Supported | Strong keyword search + vectors |
| Filtering for permissions | SQL — very flexible | Filters and security trimming patterns | Rich payload filtering | Metadata filtering | Rich query filters |
| Operations | Part of your DB | Managed by Azure | Self-host or managed | Fully managed | Self-host or managed |
| Sweet spot | Up to millions of chunks, apps already on Postgres | Azure-centric enterprises | Large collections, complex filters, self-hosting | Teams wanting zero ops | Teams already running Elastic/OpenSearch |
How we choose
- 1
Reuse what you operate
Every new database is another thing to secure, back up and monitor. If an existing Postgres or search cluster can do the job, start there.
- 2
Require hybrid search
Exact terms — product codes, error IDs, names — are common in business questions. Pure vector search misses them.
- 3
Require filtering at query time
Permissions, tenants, document status and dates must be filters in the query, not post-processing.
- 4
Estimate scale honestly
Count chunks, not documents, and growth over two years. Most business knowledge bases are smaller than people expect.
- 5
Keep the index rebuildable
Store source documents and chunking logic so you can re-embed or switch stores without data loss.
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