安装虚拟机环境

准备虚拟机, 使用的是ubuntu22.04, 太新的版本会依赖拉取有问题
安装开发工具和依赖:
sudo apt-get update sudo apt-get install -y git clang gcc make build-essential libz-dev zlib1g-dev strace libssl-dev pkg-config libreadline-dev libpg-dev flex bison libxml2-dev libxslt-dev libxml2-utils xsltproc
安装rust: curl --proto "=https" --tlsv1.2 -sSf https://sh.rustup.rs | sh
安装cargo: sudo apt-get install cargo
安装pgrx: cargo install cargo-pgrx
初始化pgrx: cargo pgrx init 这会安装12 - 17版本的pg.
耐心等待所有步骤完成后, 就可以使用pgrx新建模板来写插件了

hello pgrx

执行命令新建pg扩展项目: cargo pgrx new <project_name>
使用生成的项目模板进行插件开发

调试

如果有需要, 可以修改自己要用的pg版本配置文件来方便调试, 例如要用pg16就改.pgrx/data-16

pg_hba.conf和pg_ident.conf 支持外部工具连接pg
postgresql.conf设置日志输出级别
修改log_min_messages和client_min_messages

运行默认模板插件的函数

进入pgrx新建的项目目录后, 在控制台执行cargo pgrx run pg16表示在postgre16版本运行该插件.
默认端口起始是28800, 因此pg16开放的端口是28816(pg17就是28817),如果开放允许外部连接可以使用这个端口进去(pgrx run命令会自动接入到pg控制台模式)
执行sql安装pg扩展:

create extension <project_name>;
SELECT extname AS "Extension Name", extversion AS "Version"
FROM pg_extension;

<project_name>的来源是自己建立的项目名称.

调试用的宏

例: use pgrx::{debug1, debug5}
按照pg级别使用, 有:

debug5!
debug4!
debug3!
debug2!
debug1!
info!
notice!
warning!
error!
log!
FATAL!
PANIC!

自定义类型

see: 自定义类型官方示例
自定义类型需要实现序列化和反序列化:

#[derive(PostgresType, Deserialize, Serialize)]
pub struct MyType {}

重载运算符

see: 重载运算符官方示例

#[pg_operator(immutable, parallel_safe)]
#[opname(||)]
fn mytype_concact(mut left: MyType, right: MyType) -> MyType {
    left.0.push_str(&right.0);
    left
}

处理panic

官方提供了一个叫做PgTryBuilder的实现, 用来捕获rust中的panic.

#[pg_extern]
fn maybe_panic(panic: bool, trap_it: bool, message: &str) {
    PgTryBuilder::new(|| {
        if panic {
            panic!("panic says: {}", message)
            // std::panic::panic_any(42)
        }
    })
    .catch_rust_panic(|cause| {
        // we can catch general Rust panics.  The `error` argument is a pg_sys::panic::CaughtError::RustPanic
        // enum variant with the payload from the originating panic
        if trap_it {
            if let CaughtError::RustPanic { ereport, payload } = &cause {
                warning!("{:#?}", ereport);
                if let Some(s) = payload.downcast_ref::<String>() {
                    // we have access to the panic!() message
                    warning!("{}", s);
                    return;
                } else {
                    // this won"t happen with this example, but say the `panic_any(42)` was used
                    // instead.  Then we"d be here, and we can just raise another `panic!()`, which
                    // will be what"s ultimately reported to Postgres.
                    //
                    // In this case, Postgres" LOCATION error slot will be this line, and the CONTEXT
                    // slot will show the line number of the original `panic_any(42)` above
                    panic!("panic payload not a `String`");
                }
            }
            unreachable!("internal error:  `CaughtError` not a `::RustPanic`");
        } else {
            cause.rethrow()
        }
    })
    // finally block always runs after the catch handlers finish (even if they rethrow or raise
    // their own panic, like in this case)
    .finally(|| warning!("FINALLY!"))
    .execute()
}

在插件中执行SQL

see: 官方spi示例
see: hook列表(没有试过)
执行SQL需要用到pgrx提供的spi接口
这是一个在hook中执行sql的示例:

#[pg_guard]
pub unsafe extern "C" fn _PG_init() {
        PgTryBuilder::new(|| {
            let vec = generate_rsa_key().unwrap();
            Spi::connect(move |mut client| {
                let init_schema = format!(
                    r#"
                    create schema if not exists  {};
                "#,
                    PROJECT_SCHEMA
                );

                match client.update(init_schema.as_str(), None, None) {
                    Ok(_) => {}
                    Err(_) => {
                        return;
                    }
                };

                let init_sql = format!(
                    r#"
                create table if not exists  {}.t_rsa_key(
                    id serial8 not null primary key,
                    public_key text,
                    private_key text
                );
            "#,
                    PROJECT_SCHEMA
                );

                client.update(init_sql.as_str(), None, None).unwrap();
                let insert_sql = format!(
                    r#"
            insert into {}.t_rsa_key (public_key,private_key) values ("{}","{}");
            "#,
                    PROJECT_SCHEMA, vec[0], vec[1]
                );

                client.update(insert_sql.as_str(), None, None).unwrap();
            })
        })
        .execute();
}

关于_PG_init被调用多次的解决方式

https://stackoverflow.com/questions/28037300/in-postgresql-why-is-pg-init-called-twice
https://github.com/pgcentralfoundation/pgrx/blob/develop/pgrx-examples/shmem/README.md
(TODO: 其实我也没去处理这个问题)