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https://github.com/brettlaforge/pg_redis_pubsub
Redis Publish from PostgreSQL
https://github.com/brettlaforge/pg_redis_pubsub
hiredis postgresql postgresql-extension redis
Last synced: 3 months ago
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Redis Publish from PostgreSQL
- Host: GitHub
- URL: https://github.com/brettlaforge/pg_redis_pubsub
- Owner: brettlaforge
- License: mit
- Created: 2017-09-06T11:59:32.000Z (about 7 years ago)
- Default Branch: master
- Last Pushed: 2019-11-05T00:25:00.000Z (about 5 years ago)
- Last Synced: 2024-06-22T16:58:19.103Z (5 months ago)
- Topics: hiredis, postgresql, postgresql-extension, redis
- Language: C
- Size: 16.6 KB
- Stars: 21
- Watchers: 4
- Forks: 7
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- License: LICENSE
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README
# Redis Publish PostgreSQL Extension
This PostgreSQL extension allows you to connect to Redis and publish messages on a Redis channel from PostgreSQL.
## Requirements
To build you must have:
- PostgreSQL 9.1+
- HIREDIS C Client 13.0+
#### HIREDIS
The [HIREDIS C client library](https://github.com/redis/hiredis) is a minimalistic C client library for the Redis database.
On Ubuntu 12.04+, it can be installed using the apt-get package [libhiredis-dev](https://launchpad.net/ubuntu/+source/hiredis).
```sh
sudo apt-get install libhiredis-dev
```
On Centos 7.6 you should build HIREDIS from source, or search for recent RPMs as system repository only has version 12 available which is too old for `pg_redis_pubsub`. For example, you can use [hiredis-last-0.13.3-1.el7.remi.x86_64.rpm](https://rpms.southbridge.ru/rhel7/stable/x86_64/hiredis-last-0.13.3-1.el7.remi.x86_64.rpm) and [hiredis-last-devel-0.13.3-1.el7.remi.x86_64.rpm](https://rpms.southbridge.ru/rhel7/stable/x86_64/hiredis-last-devel-0.13.3-1.el7.remi.x86_64.rpm). Download two RPMs and run:
```sh
sudo yum install \
hiredis-last-devel-0.13.3-1.el7.remi.x86_64.rpm \
hiredis-last-0.13.3-1.el7.remi.x86_64.rpm
```
## Installation
This code is a standard PostgreSQL extension so all you need to run is:
```sh
make clean install
```
And then in the database:
```sql
CREATE EXTENSION redis;
```
## Settings
Settings can be
* specified globally using `postgresql.conf` or `ALTER SYSTEM ... SET var = 'val'`
* specified at the database level using `ALTER DATABASE ... SET var = 'val'`
* specified at the role level using `ALTER ROLE ... SET var = 'val'`
* specified at the session level using `SET var = 'val'`
### GUC settings
You can set/change the following variables with commands described above:
* **redis.host** - Redis client host setting.
* **redis.port** - Redis client port setting.
## Usage
**redis_status**()
Returns the status of the Redis client.
**redis_connect**()
Connects the Redis client using the **redis.host** and **redis.port** configuratin settings.
**redis_disconnect**()
Disconnects the Redis client.
**redis_publish**(*channel* text, *message* text)
Publishes a message on the channel provided.
If the Redis client is not currently connected, it will first create a new connection before attempting to publish the message.
## Roadmap
- Return record with columns host text, port int, connected boolean.
- Add a set of Redis connections to use?
- Add subscribe and psubscribe support that executes a PostgreSQL function?
## Examples
### Basic Example
```sql
CREATE EXTENSION IF NOT EXISTS redis;
SELECT redis_connect();
SELECT redis_publish('mychannel', 'Hello World');
SELECT redis_disconnect();
```
### Trigger Example
```sql
CREATE EXTENSION IF NOT EXISTS redis;
CREATE TABLE IF NOT EXISTS products (
id serial,
name varchar(255)
);
CREATE OR REPLACE FUNCTION after_change()
RETURNS TRIGGER AS
$$
DECLARE
channel text;
message json;
BEGIN
channel = 'products:' || NEW.id::text;
message = to_jsonb(NEW);
PERFORM redis_publish(channel, message::text);
RETURN NULL;
END;
$$
LANGUAGE plpgsql;
CREATE TRIGGER products_after_change
AFTER INSERT OR UPDATE ON products
FOR EACH ROW
EXECUTE PROCEDURE after_change();
INSERT INTO products (name) VALUES ('Ale'), ('Beer'), ('Cider');
```