Convert DuckDB to Postgres
Upload a .duckdb or .ddb file and get back a Postgres SQL script you can load straight into your database. Types are preserved rather than flattened to text. Free, no registration, up to 10MB.
Click to upload or drag and drop
CSV, Excel, SQLite, SQL, DBF (max 10 MB)
How your data is typed in Postgres
Generated from the converter's own Postgres type mapping — this is what it actually emits, not an example.
| Your data | Postgres type |
|---|---|
| Whole number | BIGINT |
| Decimal (money) | NUMERIC(10,2) |
| Floating point | DOUBLE PRECISION |
| True / false | BOOLEAN |
| Date | DATE |
| Date and time | TIMESTAMP |
| Short text | TEXT |
| Long text | TEXT |
| Binary data | BYTEA |
Working from a .duckdb file
DuckDB keeps an entire analytical database in one file, with real types behind it - decimals that are decimals, and integers wide enough to be worth checking before you move them somewhere narrower.
- →Only the main schema is read. Tables created in another schema, or in a second database attached at query time, are not part of the conversion.
- →Views in main are read as though they were tables, so a view's rows are materialised into the target rather than skipped.
- →HUGEINT is the one type with nowhere to go: no target here has a 128-bit integer, so those columns are carried across as text rather than silently truncated.
- →A DuckDB process that was killed leaves a .duckdb.wal sidecar holding everything it had not checkpointed yet. Upload the database on its own and it opens with no error and no tables at all - send the .wal file alongside it, or checkpoint before you copy the database out.
The oldest PostgreSQL this loads into
Postgres is the informal spelling and the one most people type. Since the name says nothing about a version, the useful question for this page is which server releases the generated script runs on, and that is decided by the newest piece of syntax in it.
- →The identity clause on auto-increment columns is the newest thing in the file, and it arrived in release 10. That is the floor for loading the script unedited.
- →Everything else is far older: the hex escape the script uses for binary values has been accepted since 9.0, and jsonb, which is what a JSON column is declared as, since 9.4.
- →On a server below the floor the script still loads if you delete the identity clauses by hand. The columns keep every value they were given, because each INSERT names them explicitly; they simply stop assigning new ones.
Reading DuckDB
- →Types, primary keys and NOT NULL constraints are read from the database.
- →The file is opened read-only, so your upload is never modified or upgraded in place.
Writing Postgres
- →Backslashes are left alone, because PostgreSQL treats them as ordinary characters — doubling them would corrupt every Windows path.
- →Auto-increment columns become GENERATED BY DEFAULT AS IDENTITY.
- →Binary data is written as bytea, and identifiers respect the 63-character limit.
What you get
A ZIP containing dump.sql, plus a README with the exact command to load it. If anything about your data needed a judgement call, a _warnings.txt explains it.
Load this dump into PostgreSQL: psql -U USER -d DATABASE -f dump.sql Create the database first if it does not exist: createdb -U USER DATABASE
Questions
- Is converting DuckDB to Postgres free?
- Yes. Files up to 10MB convert free with no account. There is a limit of five conversions per day per IP address.
- Will my DuckDB data keep its types in Postgres?
- Yes — that is the point. Whole numbers, decimals, dates and booleans are mapped to real Postgres types rather than everything becoming text. The mapping table above shows exactly what you get.
- Do you store my file?
- No. The file is written to a temporary directory, converted, and the directory is deleted as soon as your download has been sent.