# OpenHalo

> MySQL Compatible Postgres 14 Fork
---

[OpenHalo](https://www.openhalo.org/) is an open-source PostgreSQL kernel that provides MySQL wire protocol compatibility.

OpenHalo is based on PostgreSQL 14.10 kernel version and provides wire protocol compatibility with MySQL 5.7.32-log / 8.0 version.

Pigsty provides deployment support for OpenHalo on all supported Linux platforms.



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## Get Started

Use Pigsty’s [**standard installation process**](/docs/install/start/) with the [`mysql`](https://github.com/pgsty/pigsty/blob/v3.7.0/conf/mysql.yml) configuration template.

```bash
curl -fsSL https://repo.pigsty.io/get | bash -s v3.7.0; cd ~/pigsty;
./configure -c mysql    # Use MySQL (openHalo) configuration template
./install.yml           # Install, for production deployment please modify passwords in pigsty.yml first
```

For production deployment, please ensure to modify the password parameters in the `pigsty.yml`
configuration file before running the installation playbook.


------

## Configuration

```yaml
pg-meta:
  hosts:
    10.10.10.10: { pg_seq: 1, pg_role: primary }
  vars:
    pg_cluster: pg-meta
    pg_users:
      - {name: dbuser_meta ,password: DBUser.Meta   ,pgbouncer: true ,roles: [dbrole_admin]    ,comment: pigsty admin user }
      - {name: dbuser_view ,password: DBUser.Viewer ,pgbouncer: true ,roles: [dbrole_readonly] ,comment: read-only viewer for meta database }
    pg_databases:
      - {name: postgres, extensions: [aux_mysql]} # the mysql compatible database
      - {name: meta ,baseline: cmdb.sql ,comment: pigsty meta database ,schemas: [pigsty]}
    pg_hba_rules:
      - {user: dbuser_view , db: all ,addr: infra ,auth: pwd ,title: 'allow grafana dashboard access cmdb from infra nodes'}
    node_crontab: [ '00 01 * * * postgres /pg/bin/pg-backup full' ] # make a full backup every 1am

    # OpenHalo Ad Hoc Setting
    pg_mode: mysql                    # MySQL Compatible Mode by HaloDB
    pg_version: 14                    # The current HaloDB is compatible with PG Major Version 14
    pg_packages: [ openhalodb, pgsql-common ]  # install openhalodb instead of postgresql kernel
```


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## Usage

When accessing MySQL, the actual connection uses the `postgres` database. Please note that the concept of “database” in MySQL actually corresponds to “Schema” in PostgreSQL. Therefore, `use mysql` actually uses the `mysql` Schema within the `postgres` database.

The usernames and passwords used for MySQL are the same as those in PostgreSQL. You can manage users and permissions using the standard PostgreSQL approach.

### Client Access

OpenHalo provides MySQL wire protocol compatibility, listening on port 3306 by default, allowing direct connections from MySQL clients and drivers.

Pigsty’s [`conf/mysql`](https://github.com/pgsty/pigsty/blob/v3.7.0/conf/mysql.yml) configuration installs the `mysql` client tool by default.

You can access MySQL using the following command:

```bash
mysql -h 127.0.0.1 -u dbuser_dba
```

Currently, OpenHalo officially ensures that Navicat can access this MySQL port normally, but Intellij IDEA’s DataGrip access will result in errors.




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## Modification

The [OpenHalo](https://github.com/pgsty/openHalo) kernel installed by Pigsty is based on the [HaloTech-Co-Ltd/openHalo](https://github.com/HaloTech-Co-Ltd/openHalo) kernel with minor modifications:

- Changed the default database name from `halo0root` back to `postgres`
- Removed the `1.0.` prefix from the default version number, reverting to `14.10`
- Modified the default configuration file to enable MySQL compatibility and listen on port `3306` by default

Please note that Pigsty does not provide any warranty for using the OpenHalo kernel. Any issues or requirements encountered while using this kernel should be addressed with the original vendor.