How to Migrate from Postgres to SQLServer in PostgreSQL

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How do I migrate a PostgreSQL database to SQL Server with minimal downtime?

Export PostgreSQL schema & data, transform SQL dialect, and import into Microsoft SQL Server with tools like SSMA, pg_dump, and bcp.

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Description

Why migrate from PostgreSQL to SQL Server?

Teams switch when their stack standardizes on Microsoft tooling, requires SQL Server-only features, or needs tighter Azure integration.

Which migration methods exist?

Choose SQL Server Migration Assistant (SSMA) for an automated path, or combine pg_dump with SQL Server’s bcp/BULK INSERT for manual control.

Method 1 – SSMA step-by-step

1️⃣ Install SSMA for PostgreSQL ➜ 2️⃣ Connect to Postgres ➜ 3️⃣ Connect to SQL Server ➜ 4️⃣ Convert schema ➜ 5️⃣ Review type mapping ➜ 6️⃣ Migrate data ➜ 7️⃣ Run validation reports.

Method 2 – pg_dump + bcp

Export each table to CSV with pg_dump, create equivalent tables in SQL Server, then import using bcp or BULK INSERT. This offers version control over each script.

How do I handle schema differences?

Replace SERIAL with INT IDENTITY(1,1), convert BOOLEAN to BIT, and map BYTEA to VARBINARY(MAX). Address case-sensitive identifiers and reserved words.

What data-type conversions are essential?

NUMERIC ➜ DECIMAL, TIMESTAMPTZ ➜ DATETIMEOFFSET, TEXT ➜ NVARCHAR(MAX). Always verify precision, scale, and timezone handling.

Step-by-step migration checklist

✔️ Freeze writes ➜ ✔️ Take consistent pg_dump ➜ ✔️ Convert schema ➜ ✔️ Load static lookup tables first ➜ ✔️ Import large tables in parallel ➜ ✔️ Recreate indexes & constraints ➜ ✔️ Validate row counts ➜ ✔️ Cut over.

How can I minimize downtime?

Run an initial bulk load, keep change tracking on Postgres via logical replication, and replay deltas right before the final cut-over.

Best practices for a smooth move

Use staging servers, automate with CI scripts, store mapping rules in source control, and test application queries against SQL Server early.

Common mistakes and fixes

Mistake 1: Trusting implicit type casts—always review SSMA warnings.
Mistake 2: Importing without disabling constraints—turn them off during bulk load, then re-enable.

When should I rebuild indexes?

After all data loads complete; otherwise bulk inserts slow dramatically.

How do I validate the migration?

Compare row counts, checksum aggregates (COUNT(*), SUM(total_amount)), and run application smoke tests.

What tools help troubleshoot?

Enable SQL Server Profiler to watch inserts, use SET STATISTICS TIME ON for performance, and query SSMA logs for conversion issues.

Why How to Migrate from Postgres to SQLServer in PostgreSQL is important

How to Migrate from Postgres to SQLServer in PostgreSQL Example Usage


-- Verify row counts after migration
SELECT COUNT(*) AS pg_count FROM pg_catalog.pg_tables WHERE tablename = 'Customers';

-- SQL Server side
SELECT COUNT(*) AS mssql_count FROM dbo.Customers;

How to Migrate from Postgres to SQLServer in PostgreSQL Syntax


-- Export Customers table from PostgreSQL
'timestamp'
pg_dump \
  --host=pg_host \
  --username=pg_user \
  --table=public."Customers" \
  --column-inserts \
  --data-only \
  ecommerce > Customers.sql

-- Create equivalent table in SQL Server
CREATE TABLE dbo.Customers (
  id INT IDENTITY(1,1) PRIMARY KEY,
  name NVARCHAR(255),
  email NVARCHAR(255),
  created_at DATETIME2
);

-- Import data with bcp
bcp "ecommerce.dbo.Customers" in Customers.csv -S mssql_host -U sa -P ***** -c -t"," -r"\n"

Common Mistakes

Frequently Asked Questions (FAQs)

Does SSMA move indexes and triggers?

Yes. SSMA converts indexes, primary keys, and triggers when possible. Review the conversion report for objects that need manual rewriting.

Can I migrate incrementally?

Use logical replication on Postgres to capture changes after the initial bulk load, then replay them on SQL Server before cut-over.

What about stored procedures?

PostgreSQL functions use PL/pgSQL, which SSMA converts to T-SQL only partially. Complex procedural code often requires manual rewriting and testing.

Want to learn about other SQL terms?

dbt tests

dbt tests are declarative assertions in dbt that automatically validate data quality during model builds.

dbt utils

dbt utils is a community-maintained dbt package that adds time-saving utility macros for analytics engineers, such as generating surrogate keys, safely unioning models, and automating date spines.

dbt Tutorial Glossary: Build, Test & Deploy SQL Models

dbt is an open-source framework that lets data teams transform raw warehouse tables into tested, documented, production-ready datasets using version-controlled SQL.

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