Parquet Import

Import Parquet files into DB9 tables using COPY ... WITH (FORMAT parquet) from HTTP URLs. No external tools or ETL pipelines are required.

Installation

CREATE EXTENSION parquet;

The unqualified read_parquet() is not registered as a table-valued function and returns:

ERROR: unsupported table-valued function: read_parquet (0A000)

Call it schema-qualified instead — extensions.read_parquet(...) works:

SELECT count(*) FROM extensions.read_parquet('https://example.com/data.parquet');

You can also use COPY FROM ... WITH (FORMAT parquet) to import Parquet data into an existing table — see below.

COPY FROM Parquet

Use COPY ... WITH (FORMAT parquet) to import Parquet data from an HTTP URL into an existing table:

-- Import from HTTP URL
COPY my_table FROM 'https://example.com/export.parquet' WITH (FORMAT parquet);

The Parquet file schema must be compatible with the target table. Column names are matched by name (case-insensitive). Extra columns in the Parquet file are ignored.

Type Mapping

Parquet physical types are mapped to PostgreSQL types during COPY FROM:

Parquet Type	PostgreSQL Type
`BOOLEAN`	`BOOLEAN`
`INT32`	`INTEGER`
`INT64`	`BIGINT`
`FLOAT`	`REAL`
`DOUBLE`	`DOUBLE PRECISION`
`BYTE_ARRAY` (UTF8)	`TEXT`
`BYTE_ARRAY` (binary)	`BYTEA`
`INT96` (timestamp)	`TIMESTAMP`
`DATE` logical type	`DATE`
`TIME` logical type	`TIME`
`TIMESTAMP` logical type	`TIMESTAMP`
`DECIMAL` logical type	`NUMERIC`

Limits

Limit	Value
Max Parquet file size	100 MB
Supported Parquet versions	v1, v2
Max columns per file	Unlimited (practical limit: storage)
Remote URL fetch timeout	30 seconds
Supported compression codecs	Snappy, Gzip, Zstd, uncompressed

See Limits and Quotas for the complete list.

Error Messages

Error	Cause
`ERROR: unsupported table-valued function: read_parquet`	Unqualified `read_parquet()` is not registered. Use `extensions.read_parquet(...)` or `COPY FROM` instead.
`parquet: HTTP fetch failed (status 404)`	The remote URL returned a 404. Verify the URL is accessible.
`parquet: HTTP fetch failed (timeout)`	Remote fetch exceeded 30 seconds.
`parquet: invalid magic bytes`	The file is not a valid Parquet file.
`parquet: unsupported encoding`	File uses an unsupported encoding. Re-export with Snappy or Gzip compression.
`parquet: file too large (max 100 MB)`	File exceeds the 100 MB limit. Split into smaller files.
`ERROR: column "x" does not exist`	COPY target table is missing a column present in the Parquet file.
`ERROR: Only http:// and https:// URLs are supported`	fs9 paths are not supported for Parquet COPY. Use an HTTP URL.

Next Steps

HTTP from SQL — Fetch Parquet files from external HTTP endpoints
Extensions Overview — All 9 built-in extensions
Limits and Quotas — All operational limits