Nythrex

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

Smaller collectionsVery large collections
Managed services (Pinecone, Azure AI Search)
Qdrant / Milvus self-hosted
pgvector in managed Postgres
pgvector / OpenSearch you operate

Less to operateMore control

Rough positioning. Most business RAG systems live comfortably in the lower half.

Side by side

General characteristics; capabilities evolve quickly — check current documentation.
pgvector (PostgreSQL)Azure AI SearchQdrantPineconeElasticsearch / OpenSearch
TypeExtension to your databaseManaged search serviceOpen-source vector DB; managed cloud availableManaged vector DBSearch engine with vector support
Hybrid keyword + vectorVia Postgres full-text + vectorsBuilt in, with semantic rankingSupported (sparse + dense)SupportedStrong keyword search + vectors
Filtering for permissionsSQL — very flexibleFilters and security trimming patternsRich payload filteringMetadata filteringRich query filters
OperationsPart of your DBManaged by AzureSelf-host or managedFully managedSelf-host or managed
Sweet spotUp to millions of chunks, apps already on PostgresAzure-centric enterprisesLarge collections, complex filters, self-hostingTeams wanting zero opsTeams already running Elastic/OpenSearch

How we choose

  1. 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. 2

    Require hybrid search

    Exact terms — product codes, error IDs, names — are common in business questions. Pure vector search misses them.

  3. 3

    Require filtering at query time

    Permissions, tenants, document status and dates must be filters in the query, not post-processing.

  4. 4

    Estimate scale honestly

    Count chunks, not documents, and growth over two years. Most business knowledge bases are smaller than people expect.

  5. 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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