Firebird Foreign Data Wrapper for PostgreSQL

Firebird Foreign Data Wrapper for PostgreSQL

This is an experimental foreign data wrapper (FDW) to connect PostgreSQL to Firebird. It provides basic functionality, including both read (SELECT) and write (INSERT/UPDATE/DELETE) support.However it is still very much work-in-progress; USE AT YOUR OWN RISK.

firebird_fdw will work with PostgreSQL 9.3 or later (it was developed against the current development version) and in its current form will not work with pre-9.3 versions (although it should be simple enough to add read-only support for 9.2).

It was written for Firebird 2.5 and will probably work with Firebird 2.0 or later. It should work with earlier versions if the ‘disable_pushdowns’ option is set (see below).

Supported platforms

firebird_fdw was developed on Linux and OS X, and should run on any reasonably POSIX-compliant system.

Installation

Prerequisites:

Firebird client library (libfbclient) and API header file (ibase.h)
libfq, a slightly saner API wrapper for the Firebird C API; see: https://github.com/ibarwick/libfq

The Firebird include/library files often end up in non-standard locations; PG_CPPFLAGS and SHLIB_LINK can be used to provide the appropriate flags. For OS X they would look something like this:

export PG_CPPFLAGS="-I /Library/Frameworks/Firebird.framework/Versions/A/Headers/"
export SHLIB_LINK="-L/Library/Frameworks/Firebird.framework/Versions/A/Libraries/"

firebird_fdw is installed as a PostgreSQL extension; it requires the pg_config binary for the target installation to be in the shell path.

The usual ‘make && make install’ should take care of the actual compilation.

Usage

NOTE: these options are provisional and may change

firebird_fdw accepts the following options:

'address':
    The Firebird server's address (default: localhost)

'database':
    The name of the database to connect to

'username':
    The username to connect as (not case-sensitive)

'password':
    The user's password (note that Firebird only recognizes the first 8
    characters of a password)

'table_name':
    The Firebird table name (not case-sensitive). Cannot be used together
    with the 'query' option.

'query':
    A Firebird SQL statement producing a result set which can be treated
    like a table. Cannot be used together with the 'table_name' option.

'column_name':
    The Firebird column name (not case-sensitive).

'updatable':
    Boolean value indicating whether the foreign server as a whole,
    or an individual table, is updatable. Default is true. Note that
    table-level settings override server-level settings.

'disable_pushdowns':
    Turns off pushdowns of WHERE clause elements to Firebird. Increases
    stability at the expense of speed.

Note that while PostgreSQL allows a foreign table to be defined without any columns, firebird_fdw will raise an error as soon as any operations are carried out on it.

Example

Install the extension:

CREATE EXTENSION firebird_fdw;
CREATE FOREIGN DATA WRAPPER firebird
  HANDLER firebird_fdw_handler
  VALIDATOR firebird_fdw_validator;

Create a foreign server with appropriate configuration:

CREATE SERVER firebird_server
  FOREIGN DATA WRAPPER firebird
  OPTIONS (
    address 'localhost',
    database '/path/to/database'
 );

Create an appropriate user mapping:

CREATE USER MAPPING FOR CURRENT_USER SERVER firebird_server
  OPTIONS(username 'sysdba', password 'masterke');

Create a foreign table referencing the Firebird table_name ‘fdw_test’:

CREATE FOREIGN TABLE fb_test(
  id SMALLINT,
  val VARCHAR(2048)
)
SERVER firebird_server
OPTIONS(
  table_name 'fdw_test'
);

As above, but with aliased column names:

CREATE FOREIGN TABLE fb_test_table(
  id SMALLINT OPTIONS (column_name 'test_id'),
  val VARCHAR(2048) OPTIONS (column_name 'test_val')
)
SERVER firebird_server
OPTIONS(
  table_name 'fdw_test'
);

Create a foreign table as a Firebird query:

CREATE FOREIGN TABLE fb_test_query(
  id SMALLINT,
  val VARCHAR(2048)
)
SERVER firebird_server
OPTIONS(
  query 'SELECT id, val FROM fdw_test'
);

Features

UPDATE and DELETE statements use Firebird’s row identifier RDB$DB_KEY to operate on arbitrary rows
ANALYZE support
pushdown of some WHERE clause conditions to Firebird (including translation of built-in functions)

Limitations

Many; among the more egregious:

No Firebird transaction support
No explicit character set/encoding support
No support for some Firebird datatypes (BLOB, ARRAY)
TIMESTAMP/TIME: currently sub-second units will be truncated on insertion or update
No connection caching

Useful links

Source
https://github.com/ibarwick/firebird_fdw
http://pgxn.org/dist/firebird_fdw/
Documentation
http://www.postgresql.org/docs/current/interactive/ddl-foreign-data.html
http://www.postgresql.org/docs/current/interactive/sql-createforeigndatawrapper.html
http://www.postgresql.org/docs/current/interactive/sql-createforeigntable.html
http://www.postgresql.org/docs/current/interactive/fdwhandler.html
http://www.postgresql.org/docs/current/interactive/postgres-fdw.html
Other FDWs
https://wiki.postgresql.org/wiki/Fdw
http://pgxn.org/tag/fdw/

PGXN

PostgreSQL Extension Network

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