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This repo has relocated from https://github.com/zombodb/pgx to this location (https://github.com/tcdi/pgx). You may need to update your remote in .git/config to reflect this change.

pgx

Build Postgres Extensions with Rust!

pgx is a framework for developing PostgreSQL extensions in Rust and strives to be as idiomatic and safe as possible.

pgx supports Postgres v10-v14.

Feel free to join our Discord Server.

Key Features

A Managed Development Environment

A cargo sub-command (cargo-pgx for managing the pgx development environment
- Quickly create a new extension template crate via cargo pgx new
- Install, configure, compile, and privately install all required Postgres versions via cargo pgx init
- Run your extension and interactively test with psql via cargo pgx run
- Unit-test your extension across multiple Postgres versions via cargo pgx test
- Create installation packages for your extension via cargo pgx package

Target Multiple Postgres Versions

Support Postgres v10-v14 from the same codebase
- Postgres Rust bindings are organized into pgXX.rs modules
Use Rust feature gating to use version-specific APIs
Seamlessly test against all versions

Automatic Schema Generation

Generates DDL for common SQL objects such as
- Functions
- Types
- Enums
Hand-written SQL is supported through the extension_sql! & extension_sql_file! macros
Control the order in which SQL is executed during CREATE EXTENSION ...;

Safety First

Translates Rust panic!s into Postgres ERRORs that abort the transaction, not the process
Memory Management follows Rust's drop semantics, even in the face of panic! and elog(ERROR)
#[pg_guard] procedural macro to ensure the above
Postgres Datum is simply Option<T> where T: FromDatum -- NULL Datums are safely represented as Option::None
#[pg_test] proc-macro for unit testing in-process within Postgres

First-class UDF support

Annotate functions with #[pg_extern] to expose them to Postgres
Return impl std::iter::Iterator<Item = T> where T: IntoDatum for automatic set-returning-functions (both RETURNS SETOF and RETURNS TABLE (...) variants
DDL automatically generated

Most Postgres Data Types Transparently Converted to Rust

Postgres Type	Rust Type (as `Option<T>`)
`bytea`	`Vec<u8>` or `&[u8]` (zero-copy)
`text`	`String` or `&str` (zero-copy)
`varchar`	`String` or `&str` (zero-copy) or `char`
`"char"`	`i8`
`smallint`	`i16`
`integer`	`i32`
`bigint`	`i64`
`oid`	`u32`
`real`	`f32`
`double precision`	`f64`
`bool`	`bool`
`json`	`pgx::Json(serde_json::Value)`
`jsonb`	`pgx::JsonB(serde_json::Value)`
`date`	`pgx::Date`
`time`	`pgx::Time`
`timestamp`	`pgx::Timestamp`
`time with time zone`	`pgx::TimeWithTimeZone`
`timestamp with time zone`	`pgx::TimestampWithTimeZone`
`anyarray`	`pgx::AnyArray`
`anyelement`	`pgx::AnyElement`
`box`	`pgx::pg_sys::BOX`
`point`	`pgx::pgx_sys::Point`
`tid`	`pgx::pg_sys::ItemPointerData`
`cstring`	`&std::ffi::CStr`
`inet`	`pgx::Inet(String)` -- TODO: needs better support
`numeric`	`pgx::Numeric(String)` -- TODO: needs better support
`void`	`()`
`ARRAY[]::<type>`	`Vec<Option<T>>` or `pgx::Array<T>` (zero-copy)
`NULL`	`Option::None`
`internal`	`pgx::PgBox<T>` where `T` is any Rust/Postgres struct
`uuid`	`pgx::Uuid([u8; 16])`

There are also IntoDatum and FromDatum traits for implementing additional type conversions, along with #[derive(PostgresType)] and #[derive(PostgresEnum)] for automatic conversion of custom types.

Easy Custom Types

#[derive(PostgresType)] to use a Rust struct as a Postgres type, represented as a CBOR-encoded object in-memory/on-disk, and JSON as human-readable
- can provide custom implementations for custom in-memory/on-disk/human-readable representations
#[derive(PostgresEnum)] to use a Rust enum as a Postgres enum
DDL automatically generated

Server Programming Interface (SPI)

Safe access into SPI
Transparently return owned Datums from an SPI context

Advanced Features

Safe access to Postgres' MemoryContext system via pgx::PgMemoryContexts
Executor/planner/transaction/subtransaction hooks
Safely use Postgres-provided pointers with pgx::PgBox<T> (akin to alloc::boxed::Box<T>)
#[pg_guard] proc-macro for guarding extern "C" Rust functions that need to be passed into Postgres
Access Postgres' logging system through eprintln!-like macros
Direct unsafe access to large parts of Postgres internals via the pgx::pg_sys module
lots more!

System Requirements

rustc (minimum version 1.52) and cargo
cargo install rustfmt
git
libclang.so
- Ubuntu: libclang-dev or clang
- RHEL: clang
A relatively recent GCC which supports -dynamic-list (Linux) or -exported_symbols_list (Mac).
- CentOS 7's GCC 4 is known to not work. Use GCC 7: scl enable devtoolset-7
Build dependencies for PostgreSQL

Note that a local Postgres installation is not required. pgx will download and compile Postgres itself.

Getting Started

1. Install `cargo-pgx`

First you'll want to install the pgx cargo sub-command from crates.io. You'll use it almost exclusively during your development and testing workflow.

$ cargo install cargo-pgx

2. Initialize it

Next, pgx needs to be initialized. You only need to do this once.

$ cargo pgx init

The init command downloads Postgres versions v10, v11, v12, v13, v14 compiles them to ~/.pgx/, and runs initdb. These installations are needed by pgx not only for auto-generating Rust bindings from each version's header files, but also for pgx's test framework.

See the documentation for cargo-pgx for details on how to limit the required postgres versions.

3. Create a new extension

$ cargo pgx new my_extension
$ cd my_extension

This will create a new directory for the extension crate.

my_extension/
├── Cargo.toml
├── my_extension.control
├── sql
│   ├── lib.generated.sql
│   └── load-order.txt
└── src
    └── lib.rs

The new extension includes an example, so you can go ahead and run it right away.

4. Run your extension

$ cargo pgx run pg13  # or pg10 or pg11 or pg12 or pg14

This compiles the extension to a shared library, copies it to the specified Postgres installation (in ~/.pgx/), starts that Postgres instance and connects you, via psql, to a database named for the extension.

The first time, compilation takes a few minutes as pgx needs to generate almost 200k lines of Rust "bindings" from Postgres' header files.

Once compiled you'll be placed in a psql shell, for, in this case, Postgres 13. Now, we can load the extension and do a SELECT on the example function.

my_extension=# CREATE EXTENSION my_extension;
CREATE EXTENSION

my_extension=# SELECT hello_my_extension();
 hello_my_extension
---------------------
 Hello, my_extension
(1 row)

5. Detailed cargo pgx usage

For more details on how to manage pgx extensions see Managing pgx extensions.

Upgrading

You can upgrade your current cargo-pgx installation by passing the --force flag to cargo install:

$ cargo install --force cargo-pgx

As new Postgres versions are supported by pgx, you can re-run the pgx init process to download and compile them:

$ cargo pgx init

Digging Deeper

Caveats & Known Issues

There's probably more than are listed here, but a primary things of note are:

Threading is not really supported. Postgres is strictly single-threaded. As such, if you do venture into using threads, those threads MUST NOT call any internal Postgres function, or otherwise use any Postgres-provided pointer. There's also a potential problem with Postgres' use of sigprocmask. This was being discussed on the -hackers list, even with a patch provided, but the conversation seems to have stalled (https://www.postgresql.org/message-id/flat/5EF20168.2040508%40anastigmatix.net#4533edb74194d30adfa04a6a2ce635ba).
async interactions are unknown right now.
pgx uses lots of unsafe Rust. That's generally the nature of the beast when doing FFI wrappers, so be aware.
Not all of Postgres' internals are included or even wrapped. This isn't due to it not being possible, it's simply due to it being an incredibly large task. If you identify internal Postgres APIs you need, open an issue and we'll get them exposed, at least through the pgx::pg_sys module.
Windows is not supported. It could be, but will require a bit of work with cargo-pgx and figuring out how to compile pgx's "cshim" static library.
Sessions started before ALTER EXTENSION my_extension UPDATE; will continue to see the old version of my_extension. New sessions will see the updated version of the extension.

TODO

There's a few things on our immediate TODO list

Better trigger function support. pgx does support creating trigger functions in Rust (need examples!) but it doesn't automatically generate any of the DDL for them. This too likely needs a procmaro like #[pg_trigger]
Automatic extension schema upgrade scripts, based on diffs from a previous git tag and HEAD. Likely, this will be built into the cargo-pgx subcommand and make use of https://github.com/zombodb/postgres-parser.
More examples -- especially around memory management and the various derive macros #[derive(PostgresType/Enum)]

Contributing

We are most definitely open to contributions of any kind. Bug Reports, Feature Requests, Documentation, and even sponsorships.

If you'd like to contribute code via a Pull Request, please make it against our develop branch. The master branch is meant to represent what is currently available on crates.io.

Providing wrappers for Postgres' internals is not a straightforward task, and completely wrapping it is going to take quite a bit of time. pgx is generally ready for use now, and it will continue to be developed as time goes on. Your feedback about what you'd like to be able to do with pgx is greatly appreciated.

License

Portions Copyright 2019-2021 ZomboDB, LLC.  
Portions Copyright 2021-2022 Technology Concepts & Design, Inc. <support@tcdi.com>. 
All rights reserved.
Use of this source code is governed by the MIT license that can be found in the LICENSE file.

thomcc/pgx