How to Migrate from Postgres to Snowflake in PostgreSQL

How do I migrate data from PostgreSQL to Snowflake quickly and safely?

Export Postgres data, stage files, then COPY INTO Snowflake tables for a fast, reliable migration.

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Description

What is the fastest way to migrate Postgres data to Snowflake?

Export tables to flat files (CSV or Parquet), upload them to a Snowflake stage, and run COPY INTO to load data. This pipeline avoids row-by-row inserts and fully leverages Snowflake’s parallel loaders.

Which tools simplify the migration?

psql for exporting, AWS CLI or Snowflake PUT for staging, and SnowSQL or Galaxy’s AI-powered editor for running Snowflake SQL. ETL platforms like Fivetran work too but cost more.

Step-by-step migration guide

1.Export Postgres tables

Use COPY or \copy to write compressed CSV files. Keep header rows for easier column mapping.

2. Create an external or internal Snowflake stage

Internal stage keeps everything inside Snowflake; an S3-backed external stage scales for large datasets.

3. Upload files

Run PUT file://... for internal stages or aws s3 cp for external. Verify with LIST @stage.

4. Create target tables

Mirror Postgres schema, but switch data types (e.g., TEXT ➜ STRING, SERIAL ➜ IDENTITY). Add clustering keys later.

5.Bulk-load data

Execute COPY INTO with FILE_FORMAT options and ON_ERROR strategy (CONTINUE, SKIP_FILE, or ABORT).

6. Validate counts

Compare row counts and checksums between Postgres and Snowflake. Re-run loads with VALIDATE() if errors appear.

7. Incremental sync

Capture changes with logical replication or use Snowpipe/Streams + Tasks to keep Snowflake current until cut-over.

Best practices for large tables

Split exports by date or ID range, compress with GZIP, and use parallel PUT uploads.In Snowflake, set MAX_FILE_SIZE to balance parallelism versus overhead.

How do I minimize downtime?

Run a full load, then continuously ship WAL or CDC events. Switch applications only after deltas are caught up and validated.

How to handle sequences and IDs?

Create IDENTITY columns in Snowflake, but stop Postgres inserts before final sync or remap IDs during load.

Advanced: automate with Galaxy Collections

Store export, staging, and load queries in a shared Galaxy Collection. Teammates can endorse and reuse the scripts, ensuring a repeatable migration runbook.

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

How to Migrate from Postgres to Snowflake in PostgreSQL Example Usage


-- Full pipeline for Orders table
-- Postgres export
COPY (SELECT * FROM Orders) TO '/tmp/orders.csv' WITH (FORMAT csv, HEADER);
gzip /tmp/orders.csv

-- Snowflake stage and load
CREATE OR REPLACE STAGE pg_migration;
PUT file:///tmp/orders.csv.gz @pg_migration;
CREATE OR REPLACE TABLE Orders (
  id INT,
  customer_id INT,
  order_date DATE,
  total_amount NUMERIC(12,2)
);
COPY INTO Orders
FROM @pg_migration/orders.csv.gz
FILE_FORMAT = (TYPE=CSV SKIP_HEADER=1 FIELD_OPTIONALLY_ENCLOSED_BY='"');

How to Migrate from Postgres to Snowflake in PostgreSQL Syntax


-- 1. Export from Postgres
COPY (SELECT * FROM Customers) TO '/tmp/customers.csv' WITH (FORMAT csv, HEADER);

-- 2. Compress (optional)
gzip /tmp/customers.csv

-- 3. Create internal stage in Snowflake
CREATE OR REPLACE STAGE pg_migration;

-- 4. Upload file
PUT file:///tmp/customers.csv.gz @pg_migration AUTO_COMPRESS=FALSE;

-- 5. Create target table
CREATE OR REPLACE TABLE Customers (
  id          INT,
  name        STRING,
  email       STRING,
  created_at  TIMESTAMP
);

-- 6. Bulk-load
COPY INTO Customers
FROM @pg_migration/customers.csv.gz
FILE_FORMAT = (
  TYPE = CSV
  FIELD_OPTIONALLY_ENCLOSED_BY = '"'
  SKIP_HEADER = 1
)
ON_ERROR = ABORT_STATEMENT;

Common Mistakes

Mistake: Inserting rows one at a time with JDBC. Why wrong: it is slow and burns warehouse credits. Fix: Use bulk file loads with COPY INTO.
Mistake: Forgetting to convert time zones for TIMESTAMP WITHOUT TIME ZONE. Why wrong: Snowflake assumes UTC. Fix: Cast to TIMESTAMPTZ in Postgres export or add OFFSET columns.

Frequently Asked Questions (FAQs)

Can I keep Postgres and Snowflake in sync during migration?

Yes. Use logical replication, Debezium, or Fivetran to stream changes into Snowflake. Alternatively, stage hourly CSV extracts and automate COPY INTO with Tasks.