gem-hunter

The main things provided by this crate are some macros that help with writing Postgres extensions in Rust.

The objective (not all these are yet implemented):

• Automatic type conversions, see PgDatum and TryFromPgDatum to Into<PgDatum>
• pg_magic macro for declaring libraries as Postgres extensions
• pg_extern attribute for wrapping Rust functions in Postgres C style definitions
• panic handlers for conversion into Postgres errors
• allocator that uses Postgres palloc allocator and pfree
• tbd integrate postgres error logs with log
• tbd support all Datum types
• tbd support table like returns and manipulation
• tbd generators for the psql scripts to load functions

This project uses cargo-make for automation. While not necessary, it does help with a lot of the build tasks, so is recommended. This can be installed with cargo install cargo-make.

Once installed, it will install Postgres into the target directory for testing. There are profiles for each supported Postgres version, v10, v11, and v12. The specific minor version used is in

To run all tests with all features, for example, run:

> cargo make all-features -p v12 # if -p is left off, then the default is v12

If using cargo-make then the environment variable PG_DIR can be used to specify the location of the Postgres install.

First install Postgres. The build should be able to find the directory for the Postgres server headers, it uses the pg_config --includedir-server to attempt to find the directory. If it is unsuccessful then this environment variable is required:

PG_INCLUDE_PATH=[/path/to/postgres]/include/server # e.g. /usr/local/pgsql/include/server

For the dynamic library to compile, your project should also have .cargo/config file with content:

[target.'cfg(unix)']
rustflags = "-C link-arg=-undefineddynamic_lookup"

[target.'cfg(windows)']
rustflags = "-C link-arg=/FORCE"

This informs the linker that some of the symbols for Postgres won't be available until runtime on the dynamic library load.

Standard tests can be run with the normal cargo test, but the integration tests are a little more involved. They require a connection to an actual Postgres DB. These instructions were performed on macOS. Create a DB in Postgres to be use. In this example a DB was created in the /usr/local/var/posgres path, with the name postgres. When using cargo-make all the automation of starting, installing and setting up the DB is handled for you:

Test all features:

> cargo make all-features

Test default features:

> cargo make default-features

Test no-default-features:

> cargo make no-default-features

Testing against different versions; v10, v11, v12 are valid:

> cargo make all-features -p v10

To run the test must know the DB name to use, the DB must be running, and then the tests can be run:

export POSTGRES_TEST_DB=postgres

pg_ctl -D /usr/local/var/postgres start
cargo test

• adding
• panicking

TBD

For live discussions beyond this repository, please see this Discord.