The verdict in three sentences
For a vendor growing from 5 to 150 customers, a shared database with tenant_id isolation and Row Level Security remains the best cost and risk trade-off for 90% of accounts. A schema per tenant makes sense when customers require individual backups and restores, and a dedicated database should be a paid premium option, not the default model. Budget a 2026 ballpark of $45,000 to $120,000 and 4 to 6 months for a clean multi-tenant rebuild in Austin, with per-customer SSO and documented data isolation.
The three isolation models compared
The model you pick drives infrastructure cost, your ability to close enterprise deals and the workload on your operations team. The table below summarizes 2026 benchmarks seen at B2B software vendors with 10 to 40 employees.
| Criterion | Shared database (tenant_id + RLS) | Schema per tenant | Dedicated database per tenant |
|---|---|---|---|
| Infra cost per tenant | $3 to $7/month | $7 to $14/month | $16 to $28/month |
| Data isolation | Logical (RLS policies) | Strong logical (separate schema) | Physical |
| Restoring a single tenant | Complex (filtered export) | Simple (schema dump) | Native |
| Schema migrations | 1 migration for everyone | 150 migrations to orchestrate | 150 databases to migrate |
| Practical limit | Several thousand tenants | 300 to 1,000 schemas | Depends on ops budget |
| Enterprise sales argument | Medium | Good | Excellent |
| Operations workload | Low | Medium | High |
The classic trap is picking dedicated databases to reassure a first large prospect, then discovering at 150 tenants that every release takes a full night of orchestration. The opposite trap, a shared database without RLS and only an application-level filter, exposes you to cross-tenant data leaks as soon as a developer forgets a WHERE clause.
Budget and timeline for a multi-tenant rebuild
A multi-tenant rebuild is not limited to the database. It touches authentication, billing, observability and the compliance documentation customers will request in their security questionnaires.
| Work package | Scope | 2026 ballpark (USD) | Duration |
|---|---|---|---|
| Audit and target architecture | Data mapping, model choice, migration plan | 6,000 to 12,000 | 3 to 4 weeks |
| Isolation layer | tenant_id, RLS, automated leak tests | 11,000 to 30,000 | 4 to 6 weeks |
| Per-tenant SSO | SAML 2.0 and OIDC, SCIM provisioning, roles per tenant | 9,000 to 24,000 | 3 to 5 weeks |
| Migrating existing customers | Scripts, progressive cutover, rollback | 7,000 to 21,000 | 3 to 6 weeks |
| Per-tenant observability | Metrics, quotas, alerts, cost per tenant | 6,000 to 15,000 | 2 to 4 weeks |
| Security and privacy file | SOC 2 readiness, DPA template, isolation evidence, audit logs | 6,000 to 18,000 | 2 to 3 weeks |
| Total | 45,000 to 120,000 | 4 to 6 months |
On privacy, US enterprise buyers increasingly send SOC 2 questionnaires, and European customers will still expect a GDPR-compliant DPA, data location options, a list of sub-processors and a deletion procedure at contract end. A well-designed multi-tenant model lets you purge a tenant with a single command and prove it with a timestamped log.
Per-tenant SSO is often the commercial trigger: above 200 users, most IT directors refuse local passwords. Plan self-service SAML configuration in the admin console, otherwise support will spend 2 to 3 hours per new customer.
Mini case study
Megan, CTO of an HR software vendor in Austin, plans to grow from 5 to 150 customers within 24 months. She has three options:
- Dedicated database for everyone: 150 × $28 = $4,200/month in infrastructure, plus about 2 days per month maintaining migrations.
- Shared database for everyone: 150 × $4.50 = $675/month, but two enterprise prospects require physical isolation.
- Hybrid model: 140 tenants on the shared database ($630/month) and 10 on dedicated databases ($280/month), totaling $910/month.
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By pricing the dedicated database as a $350/month add-on, the 10 premium accounts bring in $3,500/month. The hybrid saves about $3,290/month compared with all-dedicated, roughly $39,000 per year, which funds a large share of the rebuild from year two.
FAQ
At how many customers should you move to multi-tenant?
From 10 to 20 customers, running separate instances costs more than the rebuild. Above 50 customers, each release deployed 50 times becomes a major incident risk.
Is Row Level Security enough for compliance?
It is a solid technical control if it is tested automatically on every deployment. Pair it with a DPA, access logging and encryption at rest, which 80% of security questionnaires ask for.
How long does it take to migrate 5 existing customers?
Plan 3 to 6 weeks with a tenant-by-tenant cutover and a rollback procedure. The first customer acts as a pilot, the following ones take 2 to 3 days each.
Can you offer dedicated databases later?
Yes, if the architecture isolates the data access layer from day one. Adding a dedicated database option afterwards then costs $9,000 to $18,000 instead of a rewrite.
Should SSO be included in every plan?
Most vendors reserve it for the enterprise plan, often priced at 2 to 4 times the standard plan. It is an upsell lever more than a cost.
Let's scope your project. Send your current and target customer count, isolation requirements and stack: we will price the architecture, an indicative budget and the migration timeline. Detailed quote within 48 h. WhatsApp +221 77 596 93 33.
Mohamed Bah
Fondateur, Kolonell
Passionate about digital and entrepreneurship in Africa, Mohamed has been helping Sénégalese businesses with their digital transformation since 2020. Founder of Kolonell, he believes every SME deserves a professional and accessible online présence.
