sqlite_fdw

This Release

sqlite_fdw 2.5.0

Date

2024-12-10

Status

Stable

Latest Unstable

sqlite_fdw 1.3.2 — 2021-05-26

Other Releases

Abstract

Foreign Data Wrapper for SQLite databases

Description

PostgreSQL extension which implements a Foreign Data Wrapper (FDW) for SQLite databases.

Released By

pgspider

License

PostgreSQL

Resources

Special Files

Tags

Extensions

sqlite_fdw 2.5.0: Foreign Data Wrapper for SQLite databases

Documentation

README: CI environment of sqlite_fdw.

README

SQLite Foreign Data Wrapper for PostgreSQL

This is a foreign data wrapper (FDW) to connect PostgreSQL to SQLite database file. This FDW works with PostgreSQL 13, 14, 15, 16, 17 and confirmed with SQLite 3.46.0.

+

Features

Common features

Transactions
Support INSERT/UPDATE/DELETE (both Direct modification and Foreign modification), see access control about conditions of succesfully data modification.
Support TRUNCATE by deparsing into DELETE statement without WHERE clause.
Allow control over whether foreign servers keep connections open after transaction completion. This is controlled by keep_connections and defaults to on.
Support list cached connections to foreign servers by using function sqlite_fdw_get_connections()
Support discard cached connections to foreign servers by using function sqlite_fdw_disconnect(), sqlite_fdw_disconnect_all().
Support Bulk INSERT by using batch_size option
Support INSERT/UPDATE with generated column
Support ON CONFLICT DO NOTHING
Support mixed SQLite data affinity input and filtering (SELECT/WHERE usage) for such data types as
- timestamp: text and int,
- uuid: text(32..39) and blob(16),
- bool: text(1..5) and int,
- double precision, float and numeric: real values and special values with text affinity (+Infinity, -Infinity, NaN).
Support mixed SQLite data affinity output (INSERT/UPDATE) for such data types as
- timestamp: text(default) or int,
- uuid: text(36) or blob(16)(default).
Full support for +Infinity (means ∞) and -Infinity (means -∞) special values for IEEE 754-2008 numbers in double precision, float and numeric columns including such conditions as n < '+Infinity' or m > '-Infinity'.

Pushdowning

WHERE clauses are pushdowned
Aggregate function are pushdowned
ORDER BY is pushdowned
Joins (left/right/inner/cross/semi) are pushdowned
CASE expressions are pushdowned.
LIMIT and OFFSET are pushdowned when all tables in the query are foreign tables belongs to the same PostgreSQL FOREIGN SERVER object.
Support GROUP BY, HAVING push-down.
mod() is pushdowned. In PostgreSQL this function gives argument-dependend data type, but result from SQLite always have real affinity.
upper, lower and other character case functions are not pushed down because they does not work with UNICODE character in SQLite.
WITH TIES option is not pushed down.
Bit string # (XOR) operator is not pushed down because there is no equal SQLite operator.

Notes about pushdowning

For push-down case, the number after floating point may be different from the result of PostgreSQL.

Notes about features

SQLite evaluates division by zero as NULL. It is different from PostgreSQL, which will display Division by zero error.
The data type of column of foreign table should match with data type of column in SQLite to avoid wrong result. For example, if the column of SQLite is float (which will be stored as float8), the column of foreign table should be float8, too. If the column of foreign table is float4, it may cause wrong result when SELECT.
For key option, user needs to specify the primary key column of SQLite table corresponding with the key option. If not, wrong result may occur when UPDATE or DELETE.
When sum function result value is out of range, sqlite_fdw will display Infinity value. It is different from PostgreSQL, which gives ERROR: value out of range: overflow error.
For numeric data type, sqlite_fdw use sqlite3_column_double to get value, while SQLite shell uses sqlite3_column_text to get value. Those 2 APIs may return different numeric value. Therefore, for numeric data type, the value returned from sqlite_fdw may different from the value returned from SQLite shell.
sqlite_fdw can return implementation-dependent order for column if the column is not specified in ORDER BY clause.
When the column type is varchar array, if the string is shorter than the declared length, values of type character will be space-padded; values of type character varying will simply store the shorter string.
String literals for boolean (t, f, y, n, yes, no, on, off etc. case insensitive) can be readed and filtred but cannot writed, because SQLite documentation recommends only int affinity values (0 or 1) for boolean data and usually text boolean data belongs to legacy datasets.

Also see Limitations

Supported platforms

sqlite_fdw was developed on Linux and should run on any reasonably POSIX-compliant system.

Installation

Package installation

For some Linux distributives internal packages with sqlite_fdw are avalilable.

sqlite_fdw_14 rpm for CentOS 9, RHEL 9, Rocky Linux 9, AlmaLinux 9. Also there is other versions.
sqlite_fdw git package for Arch Linux.

Source installation

Prerequisites:

libsqlite3-dev, especially sqlite.h
postgresql-server-dev, especially postgres.h
gcc
make

1. Install SQLite & Postgres Development Libraries

For Debian or Ubuntu: apt-get install libsqlite3-dev apt-get install postgresql-server-dev-XX, where XX matches your postgres version, i.e. apt-get install postgresql-server-dev-15

You can also download SQLite source code and build SQLite with FTS5 for full-text search.

2. Build and install sqlite_fdw

Add a directory of pg_config to PATH and build and install sqlite_fdw.

make USE_PGXS=1
make install USE_PGXS=1

If you want to build sqlite_fdw in a source tree of PostgreSQL, use

make
make install

Usage

CREATE SERVER options

sqlite_fdw accepts the following options via the CREATE SERVER command:

database as string, required, no default

SQLite database file address.
updatable as boolean, optional, default true

This option can allow or disallow data modification on foreign server for all foreign objects by default. Please note, this option can be overwritten on table level or have no effect because of some filesystem restrictions, see connection to SQLite database file and access control. This is only recommentadion of PostgreSQL foreign server owner user not to modify data in foreign server tables. For strong restriction see the next option force_readonly.
force_readonly as boolean, optional, default false

This option is useful if you need grant user permission to create a foreign tables on the foreign server and revoke user permission to modify any table data on this foreign server. This option with true value can disallow any write operations on foreign server table data through SQLite file readonly access mode. This option driven only by foreign server owner role can not be overwritten by any updatable option value. This is a strong restriction given by PostgreSQL foreign server owner user not to modify data in any foreign server tables. Also see Connection to SQLite database file and access control.
truncatable as boolean, optional, default false

Allows foreign tables to be truncated using the TRUNCATE command.
keep_connections as boolean, optional, default true

Allows to keep connections to SQLite while there is no SQL operations between PostgreSQL and SQLite.
batch_size as integer, optional, default 1

Specifies the number of rows which should be inserted in a single INSERT operation. This setting can be overridden for individual tables.

CREATE USER MAPPING options

There is no user or password conceptions in SQLite, hence sqlite_fdw no need any CREATE USER MAPPING command.

About access model and possible data modifications problems see about connection to SQLite database file and access control.

CREATE FOREIGN TABLE options

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

table as string, optional, no default

SQLite table name. Use if not equal to name of foreign table in PostgreSQL. Also see about identifier case handling.
truncatable as boolean, optional, default from the same CREATE SERVER option

See CREATE SERVER options section for details.
batch_size as integer, optional, default from the same CREATE SERVER option

See CREATE SERVER options section for details.
updatable as boolean, optional, default true

This option can allow or disallow data modification on separate foreign table. Please note, this option can have no effect if there is foreign server option force_readonly = true or depends on filesystem context, see about connection to SQLite database file and access control.

sqlite_fdw accepts the following column-level options via the CREATE FOREIGN TABLE command:

column_name as string, optional, no default

This option gives the column name to use for the column on the remote server. Also see about identifier case handling.
column_type as string, optional, no default

Set preferred SQLite affinity for some PostgreSQL data types can be stored in different ways in SQLite (mixed affinity case). Updated and inserted values will have this affinity. Default preferred SQLite affinity for timestamp and uuid PostgreSQL data types is text.
- Use INT value for SQLite column (epoch Unix Time) to be treated/visualized as timestamp in PostgreSQL.
- Use BLOB value for SQLite column to be treated/visualized as uuid.
key as boolean, optional, default false

Indicates a column as a part of primary key or unique key of SQLite table.

Datatypes

WARNING! The table below represents roadmap, work still in progress. Until it will be ended please refer real behaviour in non-obvious cases, where there is no ✔ or ∅ mark.

This table represents sqlite_fdw behaviour if in PostgreSQL foreign table column some affinity of SQLite data is detected. Some details about data values support see in limitations.

∅ - no support (runtime error)
V - transparent transformation
T - cast to text in SQLite utf-8 encoding, then to PostgreSQL text with current encoding of database and then transparent transformation if applicable
✔ - transparent transformation where PostgreSQL datatype is equal to SQLite affinity
V+ - transparent transformation if appliacable
? - not described/not tested
- - transparent transformation is possible for PostgreSQL (always or for some special values), but not implemented in sqlite_fdw.

SQLite NULL affinity always can be transparent converted for a nullable column in PostgreSQL.

| PostgreSQL |———––:|:—— | bool | V | bit(n) | | bytea | ∅ | date | V | float4 | | float8 | | int2 | | int4 | | int8 | ✔ | json | ? | name | ? | numeric | V | text | ? | time | V | timestamp | V |timestamp + tz| V | uuid | ∅ | varchar | ? | varbit(n) | | SQLite INT | SQLite REAL | SQLite BLOB | SQLite TEXT | SQLite TEXT but empty|SQLitenearestaffinity| ——:|:————:|:————:|:————:|:————:|———––:| | ∅ | T | V+ | ∅ | INT | V n<=64 | ∅ | ∅ | ∅ | ∅ | INT | | ∅ | ✔ | - | ? | BLOB | | V | T | V+ | NULL | ? | V+ | ✔ | T | - | NULL | REAL | V+ | ✔ | T | - | NULL | REAL | V+ | ? | T | - | NULL | INT | V+ | ? | T | - | NULL | INT | | ? | T | - | NULL | INT | | ? | T | V+ | ? | TEXT | | ? | T | V | NULL | TEXT | | V | T | ∅ | NULL | REAL | | ? | T | ✔ | V | TEXT | | V | T | V+ | NULL | ? | | V | T | V+ | NULL | ? | | V | T | V+ | NULL | ? | | ∅ |V+(only16 bytes)| V+ | ∅ | TEXT, BLOB | | ? | T | ✔ | V | TEXT | V n<=64 | ∅ | V | ∅ | ∅ | INT |

IMPORT FOREIGN SCHEMA options

sqlite_fdw supports IMPORT FOREIGN SCHEMA (PostgreSQL 9.5+) and accepts following options via the IMPORT FOREIGN SCHEMA command:

import_default as boolean, optional, default false

Allow borrowing default values from SQLite table DDL.
import_not_null as boolean, optional, default true

Allow borrowing NULL/NOT NULL constraints from SQLite table DDL.

Datatype tranlsation rules for `IMPORT FOREIGN SCHEMA`

TRUNCATE support

sqlite_fdw implements the foreign data wrapper TRUNCATE API, available from PostgreSQL 14.

As SQLite does not provide a TRUNCATE command, it is simulated with a simple unqualified DELETE operation.

Actually, TRUNCATE ... CASCADE can be simulated if we create child table of SQLite with foreign keys and ON DELETE CASCADE, and then executing TRUNCATE (which will be deparsed to DELETE).

Following restrictions apply:

TRUNCATE ... RESTART IDENTITY is not supported
SQLite tables with foreign key references can cause errors during truncating

Connection to SQLite database file and access control

In OS sqlite_fdw works as executed code with permissions of user of PostgreSQL server. Usually it is postgres OS user.

Data read access

For succesfully connection to SQLite database file you must have at least existed and correct SQLite file readable for OS user of PostgreSQL server process. This means all directories by path to the file must be also readable (listable) for OS user of PostgreSQL server process. There are no other conditions for PostreSQL database superuser to read all of SQLite data if there are also sqlite_fdw extension in the database and FOREIGN SERVER for SQLite database file.

Data change access

Data modification access in sqlite_fdw drived by both operating system and PostgreSQL.

OS restrictions can disallow any SQLite data modifications. Hence any PostgreSQL FOREIGN SERVER or FOREIGN TABLE options or GRANTs can be absolutely not effective. In this case SQLite data modification operations allowed by PostgreSQL can cause error message from SQLite like attempt to write a readonly database with result code 8.

Full list of OS-leveled conditions of data modification access to SQLite database file

Existed SQLite file is not corrupted by SQLite engine conditions.
All path elements of the file are readable (listable) for OS user of PostgreSQL server process.
The file and a directory of the file placed on readwrite filesystem. For example sqashfs is always read-only, remote sshfs can be read-only, a disk partition can be mounted in read-only mode etc.
The file is writable for OS user of PostgreSQL server process.
The directory of the file is writable for OS user of PostgreSQL server process because SQLite creates some temporary transaction files.

Full list of PostgreSQL-leveled conditions of data modification access to SQLite database file

The FOREIGN SERVER of the SQLite file have no force_readonly = true option value.
You have USAGE right GRANT for the FOREIGN SERVER.
The FOREIGN TABLE of SQLite table have no updatable = false option value.
If the FOREIGN TABLE have no updatable option, ensure FOREIGN SERVER have no updatable = false option value.

Generally for sqlite_fdw access management FOREIGN SERVER owner can be like remote access manager for other FDWs.

Remote access manager can block any data modififcations in remote database for remote user of a FDW. In this case SQLite have no user or separate access conceptions, hence FOREIGN SERVER owner combines remote access manager role with internal PostgreSQL roles such as FOREIGN SERVER access management.

Functions

As well as the standard sqlite_fdw_handler() and sqlite_fdw_validator() functions, sqlite_fdw provides the following user-callable utility functions:

SETOF record sqlite_fdw_get_connections(server_name text, valid bool)
bool sqlite_fdw_disconnect(text)

Closes connection from PostgreSQL to SQLite in the current session.
bool sqlite_fdw_disconnect_all()
sqlite_fdw_version(); Returns standard “version integer” as major version * 10000 + minor version * 100 + bugfix.

sqlite_fdw_version
--------------------
              20500

Identifier case handling

PostgreSQL folds identifiers to lower case by default, SQLite is case insensitive by default only for uppercase and lowercase ASCII base latin letters. It’s important to be aware of potential issues with table and column names.

Following SQL isn’t correct for SQLite: Error: duplicate column name: a, but is correct for PostgreSQL

	CREATE TABLE T (
	  "A" INTEGER,
	  "a" NUMERIC
	);

Following SQLs is correct for both SQLite and PostgreSQL because there is no column with names composed from ASCII base latin letters only.

	CREATE TABLE T_кир (
	  "А" INTEGER,
	  "а" NUMERIC
	);
	CREATE TABLE T_ελλ (
	  "Α" INTEGER,
	  "α" NUMERIC
	);
	CREATE TABLE T_dia (
	  "Ä" INTEGER,
	  "ä" NUMERIC
	);

For SQLite there is no difference between

	SELECT * FROM t;   -- №1
	SELECT * FROM T;   -- №2
	SELECT * FROM "t"; -- №3
	SELECT * FROM "T"; -- №4

For PostgreSQL the query with comment №4 is independend query to table T, not to table t as other queries. Please note this table name composed from ASCII base latin letters only. This is not applicable for other alphabet systems or mixed names. This is because toLower operation in PostgreSQL is Unicode operation but ASCII only operation in SQLite, hence other characters will not be changed.

	SELECT * FROM т;   -- №5
	SELECT * FROM Т;   -- №6
	SELECT * FROM "т"; -- №7
	SELECT * FROM "Т"; -- №8

In this case for PostgreSQL the query with comment №8 is independend query to table Т, not to table т as other queries. But for SQLite the queries with comments №6 and №8 belongs to table Т, and the queries with comments №5 and №7 belongs to table т.

If there is

	CREATE TABLE T (
	  A INTEGER,
	  b REAL
	);

in SQLite, both a and A , b and B columns will have the same real datasource in SQLite in follow foreign table:

	CREATE FOREIGN TABLE "SQLite test" (
	  "A" int4 NULL,
	  "B" float8 NULL,
	  "a" int8 NULL,
	  "b" numeric NULL
	)
	SERVER sqlite_server
	OPTIONS (table 'T');

Generated columns

SQLite provides support for generated columns. Behaviour of sqlite_fdw with this columns isn’t yet described.

Note that while sqlite_fdw will INSERT or UPDATE the generated column value in SQLite, there is nothing to stop the value being modified within SQLite, and hence no guarantee that in subsequent SELECT operations the column will still contain the expected generated value. This limitation also applies to postgres_fdw.

For more details on generated columns see:

Character set handling

There is no character set metadata stored in SQLite, only PRAGMA encoding; with UTF-only values (UTF-8, UTF-16, UTF-16le, UTF-16be). SQLite text output function guarantees UTF-8 encoding.

When sqlite_fdw connects to a SQLite, all strings are interpreted acording the PostgreSQL database’s server encoding. It’s not a problem if your PostgreSQL database encoding belongs to Unicode family. Otherewise interpretation transformation problems can occur. Some unproper for PostgreSQL database encoding characters will be replaced to default ‘no such character’ character or there will error like character with byte sequence 0x** in encoding "UTF8" has no equivalent in encoding "**".

Character case functions such as upper, lower and other are not pushed down because they does not work with Unicode character in SQLite.

Sqlite_fdw tested with PostgreSQL database encodings EUC_JP, EUC_KR, ISO_8859_5, ISO_8859_6, ISO_8859_7, ISO_8859_8, LATIN1, LATIN2, LATIN3, LATIN4, LATIN5, LATIN6, LATIN7, LATIN8, LATIN9, LATIN9, LATIN10, WIN1250, WIN1251, WIN1252, WIN1253, WIN1254, WIN1255, WIN1256, WIN1257 and it’s synomyms. Some other encodings also can be supported, but not tested.

Examples

Install the extension:

Once for a database you need, as PostgreSQL superuser.

	CREATE EXTENSION sqlite_fdw;

Create a foreign server with appropriate configuration:

Once for a foreign datasource you need, as PostgreSQL superuser. Please specify SQLite database path using database option.

	CREATE SERVER sqlite_server
	FOREIGN DATA WRAPPER sqlite_fdw
	OPTIONS (
          database '/path/to/database'
	);

Grant usage on foreign server to normal user in PostgreSQL:

Once for a normal user (non-superuser) in PostgreSQL, as PostgreSQL superuser. It is a good idea to use a superuser only where really necessary, so let’s allow a normal user to use the foreign server (this is not required for the example to work, but it’s secirity recomedation).

	GRANT USAGE ON FOREIGN SERVER sqlite_server TO pguser;

Where pguser is a sample user for works with foreign server (and foreign tables).

User mapping

There is no user or password conceptions in SQLite, hence sqlite_fdw no need any CREATE USER MAPPING command. About access problems see in CREATE USER MAPPING options.

Create foreign table

All CREATE FOREIGN TABLE SQL commands can be executed as a normal PostgreSQL user if there were correct GRANT USAGE ON FOREIGN SERVER. No need PostgreSQL supersuer for secirity reasons but also works with PostgreSQL supersuer.

Please specify table option if SQLite table name is different from foreign table name.

	CREATE FOREIGN TABLE t1 (
	  a integer,
	  b text
	)
	SERVER sqlite_server
	OPTIONS (
	  table 't1_sqlite'
	);

If you want to update tables, please add OPTIONS (key 'true') to a primary key or unique key like the following:

	CREATE FOREIGN TABLE t1(
	  a integer OPTIONS (key 'true'),
	  b text
	)
	SERVER sqlite_server
	OPTIONS (
	  table 't1_sqlite'
	);

If you need to convert INT SQLite column (epoch Unix Time) to be treated/visualized as TIMESTAMP in PostgreSQL, please add OPTIONS (column_type 'INT') when defining FOREIGN table at PostgreSQL like the following:

	CREATE FOREIGN TABLE t1(
	  a integer,
	  b text,
	  c timestamp without time zone OPTIONS (column_type 'INT')
	)
	SERVER sqlite_server
	OPTIONS (
	  table 't1_sqlite'
	);

As above, but with aliased column names:

	CREATE FOREIGN TABLE t1(
	  a integer,
	  b text OPTIONS (column_name 'test_id'),
	  c timestamp without time zone OPTIONS (column_type 'INT', column_name 'unixtime')
	)
	SERVER sqlite_server
	OPTIONS (
	  table 't1_sqlite'
	);

Import a SQLite database as schema to PostgreSQL:

	IMPORT FOREIGN SCHEMA someschema
	FROM SERVER sqlite_server
	INTO public;

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

Access foreign table

For the table from previous examples

	SELECT * FROM t1;

Limitations

SQL commands

COPY command for foreign tables is not supported
IMPORT of generated column is not supported
INSERT into a partitioned table which has foreign partitions is not supported. Error Not support partition insert will display.
TRUNCATE in sqlite_fdw always delete data of both parent and child tables (no matter user inputs TRUNCATE table CASCADE or TRUNCATE table RESTRICT) if there are foreign-keys references with ON DELETE CASCADE clause.
RETURNING is not supported.

Mixed affinity support

SQLite text affinity values which is different for SQLite unique checks can be equal for PostgreSQL because sqlite_fdw unifyes semantics of values, not storage form. For example 1(integer), Y(text) and tRuE(text) SQLite values is different in SQLite but equal in PostgreSQL as true values of boolean column. This is also applicable for a data with text affinity in uuid, timestamp, double precision, float and numeric columns of foreign tables. Please be carefully if you want to use mixed affinity column as PostgreSQL foreign table primary key.

Arrays

sqlite_fdw only supports ARRAY const, for example, ANY (ARRAY[1, 2, 3]) or ANY ('{1, 2 ,3}').
sqlite_fdw does not support ARRAY expression, for example, ANY (ARRAY[c1, 1, c1+0]).
For ANY(ARRAY) clause, sqlite_fdw deparses it using IN operator.

Numbers (range and precision)

For sum function of SQLite, output of sum(bigint) is integer value. If input values are big, the overflow error may occurs on SQLite because it overflow within the range of signed 64bit. For PostgreSQL, it can calculate as over the precision of bigint, so overflow does not occur.
SQLite promises to preserve the 15 most significant digits of a floating point value. The big value which exceed 15 most significant digits may become different value after inserted.
SQLite does not support numeric type as PostgreSQL. Therefore, it does not allow to store numbers with too high precision and scale. Error out of range occurs.
SQLite does not support NaN special value for IEEE 754-2008 numbers. Please use this special value very cerefully because there is no such conception in SQLite at all and NaN value treated in SQLite as NULL.
SQLite support +Infinity and -Infinity special values for IEEE 754-2008 numbers in SQL expressions with numeric context. This values can be readed with both text and real affiniy, but can be writed to SQLite only with real affinity (as signed out of range value 9.0e999).

Boolean values

sqlite_fdw boolean values support exists only for bool columns in foreign table. SQLite documentation recommends to store boolean as value with integer affinity. NULL isn’t converted, 1 converted to true, all other NOT NULL values converted to false. During SELECT ... WHERE condition_column condition converted only to condition_column.
sqlite_fdw don’t provides limited support of boolean values if bool column in foreign table mapped to SQLite text affinity.

UUID values

sqlite_fdw UUID values support exists only for uuid columns in foreign table. SQLite documentation recommends to store UUID as value with both blob and text affinity. sqlite_fdw can pushdown both reading and filtering both text and blob values.
Expected affinity of UUID value in SQLite table determined by column_type option of the column for INSERT and UPDATE commands. PostgreSQL supports both blob and text affinity.

bit and varbit support

sqlite_fdw PostgreSQL bit/varbit values support based on int SQLite data affinity, because there is no per bit operations for SQLite blob affinity data. Maximum SQLite int affinity value is 8 bytes length, hence maximum bit/varbit values length is 64 bits.
sqlite_fdw doesn’t pushdown # (XOR) operator because there is no equal SQLite operator.

Tests

Test directory have structure as following:

+---sql
|   +---13.15
|   |       filename1.sql
|   |       filename2.sql
|   |
|   +---14.12
|   |       filename1.sql
|   |       filename2.sql
|   |
.................
|   \---17.0
|          filename1.sql
|          filename2.sql
|
\---expected
|   +---13.15
|   |       filename1.out
|   |       filename2.out
|   |
|   +---14.12
|   |       filename1.out
|   |       filename2.out
|   |
.................
|   \---17.0
            filename1.out
            filename2.out

The test cases for each version are based on the test of corresponding version of PostgreSQL. You can execute test by test.sh directly. The version of PostgreSQL is detected automatically by $(VERSION) variable in Makefile. The corresponding sql and expected directory will be used to compare the result. For example, for Postgres 15.0, you can execute “test.sh” directly, and the sql/15.0 and expected/15.0 will be used to compare automatically.

Test data directory is /tmp/sqlite_fdw_test. If you have /tmp mounted as tmpfs the tests will be up to 800% faster.

Contributing

Opening issues and pull requests on GitHub are welcome. For pull request, please make sure these items below for testing:

Create test cases (if needed) for the latest version of PostgreSQL supported by sqlite_fdw. All error testcases should have a comment about test purpose.
Execute test cases and update expectations for the latest version of PostgreSQL
Test creation and execution for other PostgreSQL versions are welcome but not required.

Preferred code style see in PostgreSQL source codes. For example

type
funct_name (type arg ...)
{
	t1 var1 = value1;
	t2 var2 = value2;

	for (;;)
	{
	}
	if ()
	{
	}
}

Useful links

Source

https://github.com/pgspider/sqlite_fdw
https://pgxn.org/dist/sqlite_fdw/

General FDW Documentation

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

Other FDWs

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

License

Permission to use, copy, modify, and distribute this software and its documentation for any purpose, without fee, and without a written agreement is hereby granted, provided that the above copyright notice and this paragraph and the following two paragraphs appear in all copies.

See the License file for full details.

PGXN

PostgreSQL Extension Network