Convert Parquet to psql
Upload a .parquet file and get back a psql SQL script you can load straight into your database. Types are preserved rather than flattened to text. Free, no registration, up to 10MB.
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CSV, Excel, SQLite, SQL, DBF (max 10 MB)
How your data is typed in psql
Generated from the converter's own psql type mapping — this is what it actually emits, not an example.
| Your data | psql 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 .parquet file
Parquet is the one source here that arrives with a complete, machine-readable schema, so the conversion is a translation rather than an investigation. The interesting question is what Parquet can express that a SQL table cannot.
- →Lists, structs and maps have no scalar equivalent in a relational target, so those columns are carried across as JSON text instead of being exploded into invented columns.
- →Integer widths are kept rather than widened: int8 and int16 become a 16-bit column and int32 a 32-bit one, so the target schema stays as tight as the file was.
- →A Parquet dataset is usually a directory of part files with partition keys encoded in directory names like year=2024/. One file is read, and a column that exists only as a directory name is not inside it.
- →Rows are streamed in batches of 10,000, so a wide file never has to be held in memory all at once.
Running the script through psql
psql is PostgreSQL's command-line client rather than the database itself, and the script is written to be fed straight into it. Everything here is about the tool you run, not about the server you run it against.
- →From inside a session already open, \i dump.sql runs the file without leaving the prompt. The script contains no backslash meta-commands of its own, so nothing in it can collide with yours.
- →There is no BEGIN and no COMMIT anywhere in the file. Statements commit as they go, so a failure halfway leaves the tables already created: pass -1 to wrap the whole load in a single transaction, or -v ON_ERROR_STOP=1 to stop at the first error instead of carrying on past it.
- →The script switches standard_conforming_strings on itself instead of trusting the server default, so it behaves identically against a session that has been moved off it.
- →It sets client_encoding to UTF8 for the same reason. The file is written as UTF-8 with nothing to announce that, and psql would otherwise decode it using whatever the client locale says.
Reading Parquet
- →Parquet carries a full schema, so nothing is guessed — types, decimal precision and nullability are read directly.
- →Decimal columns keep their exact precision and scale.
Writing psql
- →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 Parquet to psql 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 Parquet data keep its types in psql?
- Yes — that is the point. Whole numbers, decimals, dates and booleans are mapped to real psql 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.