Moving a growing application off SQLite and onto a production-grade database is a rite of passage — and the trickiest part is rarely the data, it's the schema. A clean SQLite to PostgreSQL migration means resolving type mismatches, rebuilding constraints, and generating DDL that Postgres will actually accept, without hand-editing hundreds of CREATE TABLE statements.
Why Teams Move from SQLite to PostgreSQL
SQLite is fantastic for embedded apps, local development, and low-concurrency workloads, but it has real ceilings: no native network access, limited concurrent writers, and no built-in role-based access control. Once an app needs multiple app servers, heavier concurrent writes, or richer types (arrays, JSON, full-text search), PostgreSQL is the natural next step. The schema, not the data, is usually what takes the most care to get right.
What Actually Changes Between the Two Schemas
SQLite's type system is deliberately loose — it uses type affinity rather than strict column types, and there's no native BOOLEAN, UUID, or enumerated type. Common friction points when re-targeting to PostgreSQL include:
INTEGER PRIMARY KEY(SQLite's implicit rowid alias) needing to become a properSERIAL/IDENTITYcolumn- Loose
TEXT/NUMERICaffinities needing to map to precise types likeVARCHAR,NUMERIC(p,s), orTIMESTAMPTZ - SQLite's permissive foreign key enforcement (often disabled by default) versus Postgres enforcing constraints strictly
- Missing
CHECKconstraints or indexes that were never formalized because SQLite didn't require them
Getting these mappings wrong doesn't usually throw an error immediately — it shows up later as silent data-quality drift, which is worse.
Step 1: Compare the Schemas Instead of Reading Them by Eye
Rather than manually diffing table definitions, point a schema-diff tool at both databases and let it produce a structured comparison. With FoxSchema, this is a single command from the CLI:
fox compare --source sqlite://app.db --target postgres://localhost/app_pg
This walks tables, columns, keys, and indexes on both sides and reports exactly what's missing, renamed, or type-mismatched — the same process covered in more depth in how to compare two database schemas and generate migration SQL.
Step 2: Check the Readiness Panel Before Trusting the Diff
Not every schema object translates cleanly across dialects. FoxSchema's readiness panel separates what migrates automatically — tables, columns, primary/foreign keys, indexes — from what needs a manual pass, such as views, user-defined types, or any stored procedures and triggers. For an SQLite-to-Postgres move this matters most for triggers: SQLite trigger syntax has no direct Postgres equivalent, so plan to rewrite those by hand rather than expecting an automatic translation.
Step 3: Generate and Dry-Run the Migration SQL
Once the diff looks right, generate the actual DDL for the target database. FoxSchema writes dialect-correct PostgreSQL — proper SERIAL/IDENTITY handling, correctly quoted identifiers, and constraint syntax that matches Postgres' stricter enforcement model. Before running anything against a real database, use dry-run mode to see the exact SQL that would execute, with zero writes performed.
Step 4: Apply Safely, With a Way Back Out
FoxSchema never touches the source database — only the target, and only once you explicitly apply the migration. Before it runs, it takes a pre-migration snapshot of the target, and you can enable skip-on-error mode so one failing statement (say, a stray CHECK constraint SQLite never enforced) doesn't abort the whole run. That combination — dry-run, snapshot, skip-on-error — is what makes it reasonable to run a cross-dialect migration against a database you actually care about.
Where to Go From Here
If you're doing this migration once, running foxschema locally gives you a visual diff and one-click migration — install it with npm or Homebrew. If you're doing it repeatedly — across dev, staging, and CI — the self-hosted Docker image or the fox CLI fits better into a pipeline. Either way, start with a read-only compare, review the readiness panel, and only apply once the dry-run output looks exactly like what you expect. Full command reference is in the documentation, and more migration patterns are covered on the blog.
Ready to try it on your own SQLite database? Install FoxSchema and run your first compare in minutes.
