file_fdw

foreign-data wrapper for flat file access

PostgreSQL

CONTRIB

file_fdw : foreign-data wrapper for flat file access

Overview

ID	Extension	Package	Version	Category	License	Language
8980	file_fdw	file_fdw	`1.0`	FDW	PostgreSQL	C

Attribute	Has Binary	Has Library	Need Load	Has DDL	Relocatable	Trusted
--s-d--	No	Yes	No	Yes	no	no

Relationships
Need By	pg_sqlog
See Also	aws_s3 pg_bulkload pg_parquet pg_lake pg_csv pg_ducklake pg_fact_loader log_fdw omni_csv pg_sqlog

Packages

PG18	PG17	PG16	PG15	PG14
1.0	1.0	1.0	1.0	1.0

This is a built-in contrib extension ship with the PostgreSQL kernel

Install

Create this extension with:

CREATE EXTENSION file_fdw;

Usage

file_fdw: Foreign data wrapper for flat file access

Create Server

CREATE EXTENSION file_fdw;

CREATE SERVER file_server FOREIGN DATA WRAPPER file_fdw;

Read a CSV File

CREATE FOREIGN TABLE csv_data (
  id integer,
  name text,
  value numeric
)
SERVER file_server
OPTIONS (filename '/path/to/data.csv', format 'csv', header 'true');

SELECT * FROM csv_data;

Read PostgreSQL CSV Logs

CREATE FOREIGN TABLE pglog (
  log_time timestamp(3) with time zone,
  user_name text,
  database_name text,
  process_id integer,
  connection_from text,
  session_id text,
  session_line_num bigint,
  command_tag text,
  session_start_time timestamp with time zone,
  virtual_transaction_id text,
  transaction_id bigint,
  error_severity text,
  sql_state_code text,
  message text,
  detail text,
  hint text,
  internal_query text,
  internal_query_pos integer,
  context text,
  query text,
  query_pos integer,
  location text,
  application_name text,
  backend_type text,
  leader_pid integer,
  query_id bigint
)
SERVER file_server
OPTIONS (filename 'log/pglog.csv', format 'csv');

Read Program Output

CREATE FOREIGN TABLE process_list (
  pid text,
  command text
)
SERVER file_server
OPTIONS (program 'ps aux | tail -n +2', format 'text', delimiter ' ');

Table Options

Option	Description
`filename`	File path (relative to data directory). Required unless `program` is used
`program`	Shell command whose stdout is read. Required unless `filename` is used
`format`	Data format: `csv`, `text`, or `binary` (same as COPY)
`header`	`true` if file has a header row
`delimiter`	Column delimiter character
`quote`	Quote character
`escape`	Escape character
`null`	String representing NULL values
`encoding`	Data encoding
`on_error`	Error handling during type conversion
`reject_limit`	Maximum tolerated errors

Column Options

Option	Description
`force_not_null`	Do not match column values against the null string
`force_null`	Match quoted values against the null string and return NULL

CREATE FOREIGN TABLE films (
  code char(5) NOT NULL,
  title text NOT NULL,
  rating text OPTIONS (force_null 'true')
)
SERVER file_server
OPTIONS (filename '/data/films.csv', format 'csv');

file_fdw is read-only. Changing table-level options requires superuser privileges or the pg_read_server_files / pg_execute_server_program role.