Do I need a separate vector database for a document assistant?

Both platforms support pgvector, so you can keep document metadata, embeddings and access relationships together in Postgres. Store PDFs in object storage and searchable passages in the database. Test retrieval against representative questions before deciding whether another database is necessary.

How can I prevent the assistant from retrieving another client's documents?

Use document permissions and account relationships to restrict which passages a user can retrieve before sending any content to the model. Test with users from different clients and verify that searches cannot return unauthorized passages. Repeat these checks when changing retrieval queries or permission rules.

Does streaming an AI answer require a database realtime service?

Streaming generated text and subscribing to database changes are different requirements. Neon Functions support WebSockets and server-sent events for streaming, while Supabase Realtime supports database updates, broadcasts and presence. Decide separately whether your interface needs streamed answers, shared indexing progress or both, and check regional availability for the required services.

How should I test a vector index change before deploying it?

Create a branch and compare retrieval results using the same documents and fixed questions. Neon can clone existing database data through copy-on-write branching, while Supabase branches start without production data by default and require seeding or an explicit data copy. Restrict access to copied customer data, use sanitized fixtures where appropriate, and arrange branch cleanup to control costs.

What should I check if my database driver fails through a pooled connection?

Check the driver's prepared-statement settings and whether it relies on session state. Supabase's shared transaction pooler does not support prepared statements; Neon's transaction pooler supports compatible protocol-level prepared statements but not SQL PREPARE or EXECUTE. Use a suitable session or direct connection when needed, and finish database transactions before waiting for model responses.

Is scale-to-zero suitable for a production assistant?

It can reduce compute usage when the assistant has substantial idle periods, but the first request after suspension may take longer. Background indexing and frequent polling can reduce those idle periods. Measure response times after suspension and during normal use before deciding whether production compute should remain active.

How can I compare costs beyond the advertised database price?

Run the same upload, retrieval and answer-generation workflow on both platforms, then estimate monthly costs from measured usage. Include database compute, storage, history or recovery features, branches, functions, model calls and applicable transfer charges. The article's example subtotals do not establish equivalent performance or represent complete application bills.

Supabase vs Neon: AI App Features and Pricing in 2026

Backend services
Postgres for AI apps: pgvector and vector search
Database branching
Connection pooling and compute scaling
Costs for an example workload
Free plans and your first implementation

Choose Supabase when its integrated APIs and managed Realtime fit your app. Choose Neon when copy-on-write backend branches and automatic database compute scaling matter most. Both now provide Postgres, authentication, file storage and functions.

A hypothetical marketing assistant searches campaign documents and drafts cited answers. It needs PDF storage, document permission tables, vector search for relevant passages, and code calling a model. Compare how each platform supports these tasks and bills for them.

Backend services

Supabase’s platform connects Postgres with Auth, Storage, Edge Functions and data APIs. Realtime provides database-change subscriptions, broadcasts and presence. These services can support sign-in, document uploads and a shared indexing progress dashboard.

Neon’s September 2026 GA announcement lists Lakebase Postgres, S3-compatible Object Storage, Node.js Functions, Managed Better Auth and AI Gateway. It separates database compute from versioned storage. These services support the same app, including gateway model calls.

That announcement described a broader realtime service as forthcoming, while Neon Functions already support WebSockets and server-sent events. Streaming answers through functions differs from database change subscriptions. Choose what your interface needs; check Functions availability in your intended region.

Postgres for AI apps: pgvector and vector search

Both support pgvector for embedding storage and similarity search; see Supabase and Neon. Embeddings represent meaning numerically for comparison.

Neither requires a separate vector database for campaign metadata. SQL joins connect documents to accounts; transactions keep related writes consistent.

Store original PDFs in object storage and document chunks, embeddings and campaign identifiers in Postgres. Send relevant retrieved passages to the model: retrieval-augmented generation (RAG).

First, check whether retrieved passages answer 20 representative questions. Test permissions: users assigned to one client must not retrieve another’s documents. Record the embedding model, vector dimensions and distance metric to clarify future changes. DBSilk’s vector database migration guide explains what retrieval migrations should preserve.

Database branching

Supabase branches are separate instances with distinct API credentials. They start without production data or storage objects by default. Seed files or the dashboard’s Include data option can populate the database for testing with copied data.

Neon branching creates copy-on-write database clones from current or retained historical states. Branches share unchanged data, storing writes separately. Schema-only branches are available. Auth state, storage namespaces, function deployments and gateway endpoints branch alongside the database.

Branch before changing the assistant’s vector index, then compare retrieval results against fixed questions. Production clones can contain customer documents and authentication data. Restrict access; use sanitized data or synthetic fixtures where appropriate.

Budget for branch compute, storage and applicable branch charges. Included branches can still incur resource charges. Set expiry or cleanup before creating previews.

Connection pooling and compute scaling

Both pool connections for many short-lived clients. Supabase’s shared transaction pooler does not support prepared statements; its session mode does. Neon’s PgBouncer transaction pooler supports protocol-level prepared statements through compatible drivers, but not SQL PREPARE/EXECUTE or all session features. Check driver settings; connect directly when tools require session state.

Keep transactions short. Finish the assistant’s database read and transaction before waiting for the model’s answer.

Supabase projects use selected compute sizes; resizing can involve downtime. Neon offers automatic compute scaling within configured bounds and scale-to-zero during inactivity.

Suspended compute may help assistants used only during office hours. Continuous indexing or frequent polling can shorten idle periods. Measure the first request after suspension and normal response times before deciding whether production should stay active.

Costs for an example workload

Neon’s current pricing lists compute at $0.106/CU-hour (Launch) and $0.222/CU-hour (Scale). Paid plans have no monthly base fee or minimum; Free-plan compute allowances don’t carry over.

For an illustrative monthly subtotal, assume one production project, 0.25 CU for 80 billable hours, 8 GB-months of database storage, 2 GB-months of billed history and 10 GB-months of object storage. Assume no development branches.

Neon Launch item	Calculation	Cost
Database compute	0.25 × 80 × $0.106	$2.12
Database storage	8 × $0.35	$2.80
History storage	2 × $0.20	$0.40
Object Storage	10 × $0.023	$0.23
Subtotal	Sum	$5.55

At 720 running hours, this totals $22.51. These subtotals exclude separate Functions and AI Gateway charges.

Supabase Pro costs $25/organization/month, including $10 in compute credits covering one Micro instance. The baseline is $25 if that instance suffices and usage stays within 8 GB of database disk, the included 100 GB of files and other allowances. Point-in-time recovery is a paid add-on; compare restore coverage separately.

These configurations do not establish equivalent performance. Include applicable model, function, excess transfer, additional project, branch and add-on costs when comparing total app bills.

Free plans and your first implementation

Neon’s October 2 Free-plan update provides 100 projects, each with 1 GB database storage, 100 CU-hours/month, 10 branches, a six-hour restore window and 5 GB object storage; Auth supports up to 60,000 monthly active users.

Supabase Free includes 500 MB of database storage per project, 1 GB of file storage and 50,000 monthly active users. It allows two active projects, which pause after one week of inactivity. Hosted branching requires a paid plan.

First, build the path: sign-in, document upload, permitted passage retrieval and cited answer generation. Test a preview branch; inspect resource usage. Keep both trials’ documents, questions and permission checks identical.

Measure retrieval quality, response times after idle periods and app management effort. Choose the platform whose service behavior and development workflow fit that path; estimate costs from measured activity before expanding.