openHalo

OpenHalo is an open-source PostgreSQL kernel that provides MySQL wire-protocol compatibility.

openHalo is based on PostgreSQL 14.18 and provides wire-level compatibility with MySQL 5.7.32-log / 8.0. Pigsty delivers it through pg_mode: mysql and the openhalo package alias.

Pigsty supports OpenHalo deployment on all supported Linux platforms.

• RPM build spec: github.com/pgsty/rpm/rpmbuild/specs/openhalodb.spec
• DEB build spec: github.com/pgsty/deb/debbuild/openhalodb

Quick Start

Use Pigsty’s standard installation flow with the mysql template.

curl -fsSL https://repo.pigsty.io/get | bash; cd ~/pigsty;
./configure -c mysql    # Use MySQL (openHalo) template
./deploy.yml            # Install (change passwords in pigsty.yml before production use)

Cluster Config

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 ]} # 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'}
    pg_crontab: [ '00 01 * * * /pg/bin/pg-backup full' ] # full backup at 1 AM daily

    # OpenHalo specific settings
    pg_mode: mysql
    pg_version: 14
    pg_packages: [ openhalo, pgsql-common ]

OpenHalo provides a dedicated extension, aux_mysql, which includes functions and types needed for MySQL compatibility. Enable it in the postgres database to get full compatibility behavior.

• aux_mysql 1.5: MySQL Supplementary Extension
• /usr/halo-14/share/postgresql/extension/aux_mysql.control
• $libdir/mysm, mysm.so

Usage

For MySQL access, connections still use the postgres database. The MySQL “database” concept maps to PostgreSQL “schema”. So use mysql maps to the mysql schema in the postgres database.

MySQL usernames/passwords are the same PostgreSQL credentials.

Client Access

OpenHalo listens on port 3306 for MySQL wire protocol clients.

Pigsty’s conf/mysql installs a MySQL client by default.

mysql -h 127.0.0.1 -u dbuser_dba

At present, OpenHalo upstream reports Navicat works normally on this port, while IntelliJ DataGrip may fail.

Compatibility Parameters

Pigsty defaults database_compat_mode to mysql. You can further tune compatibility behavior with settings like:

mysql.listener_on = true                        # enable MySQL listener; restart required
mysql.port = 3306                               # second_port for MySQL mode; restart required
mysql.halo_mysql_version = '5.7.32-log'         # restart required
mysql.ci_collation = true                       # restart required
mysql.explicit_defaults_for_timestamp = false   # restart required
mysql.auto_rollback_tx_on_error = false         # restart required

Patch Notes

The OpenHalo kernel packaged by Pigsty is based on HaloTech-Co-Ltd/openHalo with small adjustments:

• Restore default database name from halo0root to postgres
• Remove 1.0. prefix in the default version string, keeping 14.18
• Adjust default config to enable MySQL compatibility and listen on 3306

Pigsty does not provide warranty coverage for OpenHalo kernel behavior. Kernel-specific issues should be addressed with the upstream vendor.

Warning: This kernel is currently in beta1 stage; evaluate risks carefully before production use.

Available Extensions

The OpenHalo kernel has 59 available extensions. After removing bundled PG Contrib extensions, the following extra extensions remain: