Feed format

Parquet

Apache Parquet feed

Parquet is a binary columnar format with a declared schema, which makes it the most compact and the most strictly typed way to submit a product feed. OpenAI prefers it, and it is the only format documented here where the field types are part of the file rather than a convention.

Specification

File extension: .parquet
Content type: application/vnd.apache.parquet
Compression: Compression is internal to the format. Zstd is the preferred codec for an OpenAI feed, and there is no separate gzip step.
One product is: A binary file holding a schema and then the data stored column by column rather than row by row. One product is a row in the logical sense, but its values are physically grouped with the same field from every other product, which is what makes it compress so well.
Escaping: There is no escaping, because the format is not text: a comma, a quote or a newline inside a description is simply part of a value. What replaces escaping is type discipline, and the rule that matters is declaring identifiers as strings rather than integers so leading zeros survive.

A valid apache parquet feed

Two products, every required attribute, nothing omitted for brevity. Copy it and replace the values.

# Parquet is a binary columnar format, so what matters is the schema rather than the bytes.
# The same two products as the other examples on this site, as a Parquet schema:

message product {
  required binary item_id        (STRING);
  required binary title          (STRING);
  required binary description    (STRING);
  required binary url            (STRING);
  required binary image_url      (STRING);
  required binary availability   (STRING);
  required binary price          (STRING);   # "49.00 GBP" — amount and ISO code in one value
  required binary brand          (STRING);
  required binary seller_name    (STRING);
  optional binary gtin           (STRING);   # string, not integer: leading zeros are significant
  optional binary group_id       (STRING);
  optional boolean listing_has_variations;
  optional group  variant_dict (MAP) {
    repeated group key_value {
      required binary key   (STRING);
      required binary value (STRING);
    }
  }
}

Which channels accept it

Channel support for Parquet
Channel	Support	Notes
OpenAI	Preferred	The preferred format, with zstd compression.
Google Shopping	Not supported	Google takes text or XML files.
Meta	Not supported	Meta takes CSV, TSV, XML or Google Sheets.
Microsoft Advertising	Not supported	Microsoft takes tab-delimited text or XML.
Pinterest	Not supported	Pinterest takes CSV, TSV or XML.

What breaks a apache parquet feed

Typing an identifier as a number destroys it

Parquet will happily store a GTIN as an int64, and a twelve-digit UPC beginning with zero loses that zero permanently. Unlike a text format, there is no way to tell afterwards that it was ever there. Every identifier belongs in a string column.

You cannot inspect it with an editor

A broken CSV can be opened and read. A Parquet file requires tooling, which means a validation step in your own pipeline is not optional: whatever you cannot see, you have to check programmatically before it is pushed.

The schema has to stay stable

Because the types are declared in the file, a generator that infers them from the data can produce a different schema when the data changes, for instance typing a column as integer on the day every value happens to be numeric. Declare the schema explicitly rather than letting a library guess it per run.

It is the right choice only at scale

Parquet earns its complexity on a large catalogue, where the compression and the typing both pay off. For a few thousand products, gzipped TSV or JSONL is easier to build, easier to debug and accepted by the same channel.

Frequently asked questions

Why does OpenAI prefer Parquet for a product feed?

Because it is columnar and typed: a large catalogue compresses far smaller than the equivalent text file, and the field types are declared in the file rather than inferred from the values.

How should GTINs be typed in a Parquet feed?

As strings, always. An integer column silently discards leading zeros, and because the format is binary there is no way to notice afterwards.

Do I need Parquet, or will gzipped TSV do?

Gzipped TSV is accepted and is much easier to produce and debug. Parquet is worth the extra work on a large catalogue, where the size and typing benefits are real.

What compression does a Parquet feed use?

Compression is built into the format, with zstd preferred for an OpenAI feed. There is no separate gzip step, and adding one is not expected.

Errors this format causes

Invalid value: GTIN The "Invalid value: GTIN" error means the feed supplied a value in the gtin attribute that is not a structurally valid Global Trade Item Number. Unlike a missing GTIN this is usually a disapproval rather than a warning, because a wrong identifier matches the item to the wrong product rather than to none.

Related concepts

Product feed A product feed is a structured file listing every item a shop sells, with one row per purchasable item and one column per attribute the destination understands. Sales channels use it to build their own copy of a catalogue, which is why a feed is a translation of a shop's data into another system's schema rather than an export of it.

Primary sources

Channel specifications change. These are the official documents this page is based on.

Last reviewed 18 September 2026 View as markdown