Contents

• Firebird Foreign Data Wrapper for PostgreSQL
  • Features
  • Supported platforms
  • Installation
    • From packages
    • From source
  • Usage
    • CREATE SERVER options
    • CREATE FOREIGN TABLE options
    • IMPORT FOREIGN SCHEMA options
  • Examples
  • Limitations
  • TAP tests
  • Development roadmap
  • Useful links

Firebird Foreign Data Wrapper for PostgreSQL

This is a foreign data wrapper (FDW) to connect PostgreSQL to Firebird. It provides both read (SELECT) and write (INSERT/UPDATE/DELETE) support, as well as pushdown of some operations. While it appears to be working reliably, please be aware this is still very much work-in-progress; USE AT YOUR OWN RISK.

firebird_fdw is designed to be compatible with PostgreSQL 9.2 ~ 11. Write support is only available in PostgreSQL 9.3 and later. It is not designed to work with forks of the main PostgreSQL community version.

firebird_fdw 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). It works with Firebird 3.0.x but has not yet been extensively tested with that version, and does not take advantage of all new Firebird 3 features. This will be addressed in future releases.

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)
• Connection caching
• Supports triggers on foreign tables (PostgreSQL 9.4 and later)
• Supports IMPORT FOREIGN SCHEMA (PostgreSQL 9.5 and later)

Supported platforms

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

Installation

From packages

RPM packages for CentOS and derivatives are available via the Fedora “copr” build system; for details see here: https://copr.fedorainfracloud.org/coprs/ibarwick/firebird_fdw/

From source

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

  NOTE the latest libfq version should be used with the current firebird_fdw version, as the two are usually developed in tandem.

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.

USE_PGXS=1 make install should take care of the actual compilation and installation.

Usage

CREATE SERVER options

firebird_fdw accepts the following options via the CREATE SERVER command:

'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)

'updatable':
    Boolean value indicating whether the foreign server as a whole
    is updatable. Default is true. Note that this can be overridden
    by table-level settings.

CREATE FOREIGN TABLE options

firebird_fdw accepts the following table-level options via the CREATE FOREIGN TABLE command:

'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.

'disable_pushdowns':
    Turns off pushdowns of WHERE clause elements to Firebird. Useful
    mainly for debugging and benchmarking.

'updatable':
    Boolean value indicating whether the table is updatable. Default is `true`.
    Note that this overrides the server-level setting.

'estimated_row_count':
    Integer indicating the expected number of rows in the Firebird table, or
    rows which would be returned by the statement defined in 'query'. If not
    set, an attempt will be made to determine the number of rows by executing
    "SELECT COUNT(*) FROM ...", which can be inefficient, particularly for
    queries.

The following column-level option is available:

'column_name':
    The Firebird column name (not case-sensitive), if different to the column
    name defined in the foreign table. This can also be used for foreign
    tables defined with the `query` option.

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.

IMPORT FOREIGN SCHEMA options

firebird_fdw supports IMPORT FOREIGN SCHEMA (when running with PostgreSQL 9.5 or later), with the following options:

'import_not_null':
    Determines whether column `NOT NULL` constraints are included in the definitions
    of foreign tables imported from a Firebid server. The default is `true`.

'import_views':
    Determines whether Firebird views are imported as foreign tables. The default is `true`.

'updatable':
    If set to 'false', mark all imported foreign tables as not updatable. The default is `true`.

'verbose':
    Logs the name of each table or view being imported at log level `INFO`.

Examples

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 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 $$ SELECT id, val FROM fdw_test $$
);

Import a Firebird schema:

IMPORT FOREIGN SCHEMA someschema
  LIMIT TO (sometable)
  FROM SERVER firebird_server
  INTO public;

Note: someschema has no particular meaning and can be set to an arbitrary value.

Limitations

• Works with Firebird 3.x, but does not yet support all 3.x features
• No support for Firebird ARRAY datatype
• No consideration given to object names which may require quoting when passed between PostgreSQL and Firebird
• The result of the Firebird query is copied into memory before being processed by PostgreSQL; this can be improved by using Firebird cursors

TAP tests

Simple TAP tests are provided in the t/ directory. These require a running Firebird database to be available; provide connection details for this with the standard Firebird environment variables ISC_DATABASE, ISC_USER and ISC_PASSWORD. Additionally, PostgreSQL must have been compiled with the --enable-tap-tests option.

Run with

make prove_installcheck

The TAP tests will create temporary tables in the Firebird database and remove them after test completion.

Development roadmap

Haha, nice one. I should point out that firebird_fdw is an entirely personal project carried out by myself in my (limited) free time for my own personal gratification. While I’m happy to accept feedback, suggestions, feature requests, bug reports and (especially) patches, please understand that development is entirely at my own discretion depending on (but not limited to) available free time and motivation.

However if you are a commercial entity and wish to have any improvements etc. carried out within a plannable period of time, this can be arranged via my employer.

Having said that, things I would like to do are:

• improve support for Firebird 3.0 features
• add support for missing data types
• improve support for recent features to the PostgreSQL FDW API.

Useful links

• Source
• https://github.com/ibarwick/firebird_fdw (public mirror)

• http://pgxn.org/dist/firebird_fdw/

• Blog (including release notes)

• http://sql-info.de/postgresql/firebird-fdw/index.html

• General FDW Documentation

• https://www.postgresql.org/docs/current/static/ddl-foreign-data.html
• https://www.postgresql.org/docs/current/static/sql-createforeigndatawrapper.html
• https://www.postgresql.org/docs/current/static/sql-createforeigntable.html
• https://www.postgresql.org/docs/current/static/sql-importforeignschema.html
• https://www.postgresql.org/docs/current/static/fdwhandler.html

• https://www.postgresql.org/docs/current/static/postgres-fdw.html

• Other FDWs

• https://wiki.postgresql.org/wiki/Fdw
• https://pgxn.org/tag/fdw/

If you appreciate PostgreSQL’s psql client, why not try fbsql, a psql-style client for Firebird? See: https://github.com/ibarwick/fbsql for details.