Babelfish

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

Overview

Pigsty lets you deploy Babelfish in mssql mode and provide, on top of PostgreSQL:

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

In Pigsty v4, Babelfish supports PostgreSQL 17/18. The default template uses pg_version: 17, and Babelfish is part of Pigsty’s standard delivery path with support for all Linux platforms.

Current Behavior

Compared with older Babelfish/PG15 docs, current behavior is:

• 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:

./configure -c mssql [-v 17/18]
./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  # optional: 18
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

With Pigsty service abstraction you can also use:

• 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.
• Not all native PostgreSQL extensions are directly usable on Babelfish kernels; validate package availability and compatibility first.
• Tighten HBA and network exposure for production; do not keep demo-level open rules.

Related Docs

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

Available Extensions

The Babelfish kernel has 55 available extensions. After removing bundled PG Contrib extensions, the following extra extensions remain: