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Parquet
What is a Parquet file?
Columnar storage for large datasets. Far smaller and faster to query than CSV.
What Parquet is
Parquet is a binary format, meaningful only to a program that knows it. It is used for archiving and moving data between programs.
The extension is .parquet, and the full name is Apache Parquet. Both matter less than what the file can hold, which is what the rest of this page is about.
Where Parquet came from
Apache Software Foundation published it in 2013.
Age is worth knowing here for one practical reason: the older a format is, the more programs have had time to learn it.
The specification is public
Anyone can implement it without asking permission or paying a licence, which is why it turns up in so many programs and why files written twenty years ago still open.
Nothing is thrown away
Parquet stores its content exactly. Saving it again changes nothing, so it can be opened, edited and re-saved as often as you like without accumulating damage — which is what makes it a working format rather than a delivery one.
What it does to protect itself
Parquet carries a checksum, so a damaged file is detected rather than silently mis-read and optional encryption.
An encrypted file has to be unlocked before anything can convert it, here or anywhere else — a password is not something a converter can work around, and one that claimed to could not be trusted with the file either.
What opens Parquet
pandas, Apache Spark and DuckDB read it, and so do most programs of the same kind.
If a file will not open, the format is rarely the problem — it is more often that the program predates it. Converting to something older is the reliable way past that, and it is what the rest of this site is for.
Opening it in a browser
No browser reads it.
That is the single most common reason to convert it: not that the format is bad, but that the place you want to show the file cannot read it.
It is a delivery format
Parquet is meant to be handed over rather than worked in. Editing one is possible and rarely pleasant; the sane approach is to change the source and export again.
What goes wrong with it
The recurring complaints: support outside its home ground is uneven.
None of these is a reason to avoid the format. They are the things worth knowing before you are surprised by one, which is a different claim and a more useful one.
The facts, in one place
| Extension | .parquet |
|---|---|
| Media type | application/vnd.apache.parquet |
| Published by | Apache Software Foundation |
| First published | 2013 |