Babelfish

Babelfish is a PostgreSQL-based SQL Server compatibility layer, open-sourced by AWS.

Overview

Deploy Babelfish in mssql mode to add these features to PostgreSQL:

• SQL Server wire protocol compatibility (TDS, 1433)
• T-SQL compatibility
• Unified integration with Pigsty capabilities (HA, backup, monitoring, IaC)

Pigsty provides PostgreSQL 17/18-compatible Babelfish packages. The template defaults to pg_version: 17. See the package lists for version and platform availability.

./configure -c mssql ignores -v. To select PG18, explicitly adjust the generated configuration and check packages. In development sources, -v overrides the version for fork/mssql; see the MSSQL template.

Current Behavior

The current behavior differs from older Babelfish/PG15 documentation as follows:

• Supported kernel majors are PG17/18; the template defaults to PG17 (pg_version: 17)
• Default package group: babelfish + pgsql-common + sqlcmd
• Mainstream platform coverage:
  • OS: el8, el9, el10, d12, d13, u22, u24, u26
  • Arch: x86_64, aarch64
• mssql template no longer requires an extra mssql repo module (defaults to node,infra,pgsql)

Older docs may still contain deprecated naming. Pigsty now consistently uses Babelfish and babelfish aliases.

Quick Start

Use the built-in Pigsty template:

The commands below use the v4.5.0 template. Development sources moved it to conf/fork/mssql.yml; use -c fork/mssql with those sources.

./configure -c mssql
./deploy.yml

After deployment, connect directly with SQL Server clients:

sqlcmd -S <ip>,1433 -U dbuser_mssql -P DBUser.MSSQL -d mssql

Key Configuration

Core parameters in the mssql template:

pg_mode: mssql
pg_version: 17
pg_packages: [ babelfish, pgsql-common, sqlcmd ]
pg_libs: 'babelfishpg_tds, pg_stat_statements, auto_explain'

pg_databases:
  - name: mssql
    baseline: mssql.sql
    extensions:
      - { name: uuid-ossp }
      - { name: babelfishpg_common }
      - { name: babelfishpg_tsql }
      - { name: babelfishpg_tds }
      - { name: babelfishpg_money }
      - { name: pg_hint_plan }
      - { name: system_stats }
      - { name: tds_fdw }
    parameters: { 'babelfishpg_tsql.migration_mode': 'multi-db' }

pg_hba_rules:
  - { user: dbuser_mssql, db: mssql, addr: intra, auth: md5, order: 525 }

pg_default_services:
  - { name: primary, port: 5433, dest: 1433 }
  - { name: replica, port: 5434, dest: 1433 }

Connectivity and Ports

Babelfish clusters expose two protocol endpoints:

• PostgreSQL protocol: 5432
• SQL Server protocol (TDS): 1433

Through Pigsty services, you can also use these ports:

• 5433: fixed route to primary 1433
• 5434: route to readable node 1433

# Primary write access
sqlcmd -S <any-node-ip>,5433 -U dbuser_mssql -P DBUser.MSSQL

# Read replica query
sqlcmd -S <any-node-ip>,5434 -U dbuser_mssql -P DBUser.MSSQL

Notes

• Babelfish auth rules must use md5 instead of default scram-sha-256.
• Default migration mode is multi-db; switch with babelfishpg_tsql.migration_mode if needed.
• Some native PostgreSQL extensions cannot run directly on Babelfish kernels. Verify package availability and compatibility first.
• For production, restrict HBA rules and network access. Do not keep the open rules from the demonstration configuration.

Related Docs

• mssql config template
• PGSQL kernel mode config
• Official SQL Server sqlcmd docs

Available Extensions

The table lists selected non-Contrib extensions for reference. Query the target instance to confirm actual availability and versions.