78 releases
0.7.4 | Mar 14, 2023 |
---|---|
0.7.2 | Feb 23, 2023 |
0.6.1 | Dec 6, 2022 |
0.6.0-alpha.2 | Nov 18, 2022 |
0.0.8 | Jul 28, 2020 |
#239 in Database interfaces
100 downloads per month
Used in 8 crates
10MB
338K
SLoC
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 v11-v15.
Feel free to join our Discord Server.
Key Features
- A fully managed development environment with
cargo-pgx
cargo pgx new
: Create new extensions quicklycargo pgx init
: Install new (or register existing) PostgreSQL installscargo pgx run
: Run your extension and interactively test it inpsql
(orpgcli
)cargo pgx test
: Unit-test your extension across multiple PostgreSQL versionscargo pgx package
: Create installation packages for your extension- More in the
README.md
!
- Target Multiple Postgres Versions
- Support Postgres v11-v15 from the same codebase
- Use Rust feature gating to use version-specific APIs
- Seamlessly test against all versions
- Automatic Schema Generation
- Implement extensions entirely in Rust
- Automatic mapping for many Rust types into PostgreSQL
- SQL schemas generated automatically (or manually via
cargo pgx schema
) - Include custom SQL with
extension_sql!
&extension_sql_file!
- Safety First
- Translates Rust
panic!
s into PostgresERROR
s that abort the transaction, not the process - Memory Management follows Rust's drop semantics, even in the face of
panic!
andelog(ERROR)
#[pg_guard]
procedural macro to ensure the above- Postgres
Datum
s areOption<T> where T: FromDatum
NULL
Datums are safely represented asOption::<T>::None
- Translates Rust
- First-class UDF support
- Annotate functions with
#[pg_extern]
to expose them to Postgres - Return
pgx::iter::SetOfIterator<'a, T>
forRETURNS SETOF
- Return
pgx::iter::TableIterator<'a, T>
forRETURNS TABLE (...)
- Create trigger functions with
#[pg_trigger]
- Annotate functions with
- Easy Custom Types
#[derive(PostgresType)]
to use a Rust struct as a Postgres type- By default, represented as a CBOR-encoded object in-memory/on-disk, and JSON as human-readable
- Provide custom in-memory/on-disk/human-readable representations
#[derive(PostgresEnum)]
to use a Rust enum as a Postgres enum- Composite types supported with the
pgx::composite_type!("Sample")
macro
- Server Programming Interface (SPI)
- Safe access into SPI
- Transparently return owned Datums from an SPI context
- Advanced Features
- Safe access to Postgres'
MemoryContext
system viapgx::PgMemoryContexts
- Executor/planner/transaction/subtransaction hooks
- Safely use Postgres-provided pointers with
pgx::PgBox<T>
(akin toalloc::boxed::Box<T>
) #[pg_guard]
proc-macro for guardingextern "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 thepgx::pg_sys
module - New features added regularly!
- Safe access to Postgres'
System Requirements
- A Rust toolchain:
rustc
,cargo
, andrustfmt
. The recommended way to get these is from https://rustup.rs † git
libclang
5.0 or greater (required by bindgen)- Ubuntu:
apt install libclang-dev
orapt install clang
- RHEL:
yum install clang
- Ubuntu:
tar
bzip2
- GCC 7 or newer
- PostgreSQL's build dependencies ‡
† PGX has no MSRV policy, thus may require the latest stable version of Rust, available via Rustup
‡ A local PostgreSQL server installation is not required. cargo pgx
can download and compile PostgreSQL versions on its own.
How to: GCC 7 on CentOS 7
In order to use GCC 7, install scl
and enter the GCC 7 development environment:
yum install centos-release-scl
yum install devtoolset-7
scl enable devtoolset-7 bash
Getting Started
First install the cargo-pgx
sub-command and initialize the development environment:
cargo install --locked cargo-pgx
cargo pgx init
The init
command downloads currently supported PostgreSQL versions, compiles them to ~/.pgx/
, and runs initdb
. It's also possible to use an existing (user-writable) PostgreSQL install, or install a subset of versions, see the README.md
of cargo-pgx
for details.
cargo pgx new my_extension
cd my_extension
This will create a new directory for the extension crate.
$ tree
.
├── Cargo.toml
├── my_extension.control
├── sql
└── src
└── lib.rs
2 directories, 3 files
The new extension includes an example, so you can go ahead and run it right away.
cargo pgx run
This compiles the extension to a shared library, copies it to the specified Postgres installation, starts that Postgres instance and connects you to a database named the same as the extension.
Once cargo-pgx
drops us into psql
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)
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 --locked 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
Mapping of Postgres types 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 |
&core::ffi::CStr |
inet |
pgx::Inet(String) -- TODO: needs better support |
numeric |
pgx::Numeric<P, S> or pgx::AnyNumeric |
void |
() |
ARRAY[]::<type> |
Vec<Option<T>> or pgx::Array<T> (zero-copy) |
int4range |
pgx::Range<i32> |
int8range |
pgx::Range<i64> |
numrange |
pgx::Range<Numeric<P, S>> or pgx::Range<AnyRange> |
daterange |
pgx::Range<pgx::Date> |
tsrange |
pgx::Range<pgx::Timestamp> |
tstzrange |
pgx::Range<pgx::TimestampWithTimeZone> |
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.
Digging Deeper
- cargo-pgx sub-command
- Custom Types
- Postgres Operator Functions and Operator Classes/Families
- Shared Memory Support
- various examples
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). - How to correctly interact with Postgres in an
async
context remains unexplored. pgx
wraps a lot ofunsafe
code, some of which has poorly-defined safety conditions. It may be easy to induce illogical and undesirable behaviors even from safe code withpgx
, and some of these wrappers may be fundamentally unsound. Please report any issues that may arise.- 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 compilepgx
's "cshim" static library. - Sessions started before
ALTER EXTENSION my_extension UPDATE;
will continue to see the old version ofmy_extension
. New sessions will see the updated version of the extension. pgx
is used by many "in production", but it is not "1.0.0" or above, despite that being recommended by SemVer for production-quality software. This is because there are many unresolved soundness and ergonomics questions that will likely require breaking changes to resolve, in some cases requiring cutting-edge Rust features to be able to expose sound interfaces. While a 1.0.0 release is intended at some point, it seems prudent to wait until it seems like a 2.0.0 release would not be needed the next week and the remaining questions can be deferred.
TODO
There's a few things on our immediate TODO list
- 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)]
Feature Flags
PGX has optional feature flags for Rust code that do not involve configuring the version of Postgres used, but rather extend additional support for other kinds of Rust code. These are not included by default.
"time-crate": interop with the time
crate
pgx
once used direct interop with the excellent time crate.
However, due to complications involving performance and accurate interop with Postgres,
this feature is now considered deprecated in favor of a lower-overhead interop.
You may still request implementations of TryFrom<time::Type> for pgx::MatchingType
and From<time::Type> for pgx::MatchingType
by enabling the "time-crate"
feature.
"unsafe-postgres": Allow compilation for Postgres forks that have a different ABI
As of Postgres v15, forks are allowed to specify they use a different ABI than canonical Postgres.
Since pgx makes countless assumptions about Postgres' internal ABI it is not possible for it to
guarantee that a compiled pgx extension will probably execute within such a Postgres fork. You,
dear compiler runner, can make this guarantee for yourself by specifying the unsafe-postgres
feature flag. Otherwise, a pgx extension will fail to compile with an error similar to:
error[E0080]: evaluation of constant value failed
--> pgx/src/lib.rs:151:5
|
151 | / assert!(
152 | | same_slice(pg_sys::FMGR_ABI_EXTRA, b"xPostgreSQL\0"),
153 | | "Unsupported Postgres ABI. Perhaps you need `--features unsafe-postgres`?",
154 | | );
| |_____^ the evaluated program panicked at 'Unsupported Postgres ABI. Perhaps you need `--features unsafe-postgres`?', pgx/src/lib.rs:151:5
|
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.
Hacking
If you're hacking on pgx
and want to ensure your test will run correctly, you need to have the current
implementation of cargo-pgx
(from the revision you're working on) in your PATH
.
An easy way would be to install cargo-local-install:
cargo install cargo-local-install
and then run cargo local-install
to install cargo-pgx
as specified in top-level's Cargo.toml.
Don't forget to prepend /path/to/pgx/bin
to your PATH
!
This approach can also be used in extensions to ensure a matching version of cargo-pgx
is used.
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.
Dependencies
~8–12MB
~214K SLoC