How to Migrate from Oracle to Snowflake in PostgreSQL

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How do I migrate data from Oracle to Snowflake?

Move Oracle schemas and data to Snowflake using staged files, converted DDL, and COPY INTO.

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Description

Why migrate from Oracle to Snowflake?

Snowflake’s elastic compute, zero-copy cloning, and pay-per-second billing lower cost and simplify scaling versus fixed Oracle licenses.

What are the high-level migration steps?

Inventory objects, convert DDL, export data, stage files, load with COPY INTO, validate results, and switch applications.

How do I export Oracle data efficiently?

Use Oracle Data Pump with parallel workers to dump each ecommerce table (Customers, Orders, Products, OrderItems) to compressed CSV files.

Sample expdp command

expdp system/**** DIRECTORY=DATA_PUMP_DIR DUMPFILE=orders.dmp LOGFILE=orders.log TABLES=ORDERS PARALLEL=4

How do I stage files in Snowflake?

Create an external stage that points to S3, Azure, or GCS and upload the exported CSV files.

Sample stage creation

CREATE STAGE oracle_migration URL='s3://acme-migration' FILE_FORMAT=(TYPE=CSV FIELD_OPTIONALLY_ENCLOSED_BY='"');

What is the `COPY INTO` syntax?

COPY INTO reads staged files in parallel and loads them into Snowflake tables with configurable error handling.

Example COPY for Orders

COPY INTO Orders FROM @oracle_migration/orders FILE_FORMAT=(TYPE=CSV FIELD_OPTIONALLY_ENCLOSED_BY='"') ON_ERROR=CONTINUE;

How do I validate row counts?

Compare SELECT COUNT(*) results in Oracle and Snowflake, then log differences in an audit table for automation.

How can I automate schema conversion?

SnowConvert, AWS SCT, or SQL translation scripts remap Oracle data types and constraints; review sequences and identity columns manually.

Best practices for production cut-over?

Freeze Oracle writes, run incremental exports, reload deltas, switch connections via feature flag, and keep Oracle read-only for easy rollback.

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

How to Migrate from Oracle to Snowflake in PostgreSQL Example Usage


-- Migrate Customers table
-- 1. Export from Oracle (already done)
-- 2. Stage files in Snowflake
CREATE OR REPLACE STAGE oracle_migration_customers
  URL='s3://acme-migration/customers'
  FILE_FORMAT=(TYPE=CSV FIELD_OPTIONALLY_ENCLOSED_BY='"');

-- 3. Load into Snowflake
COPY INTO Customers (id, name, email, created_at)
FROM @oracle_migration_customers
FILE_FORMAT=(TYPE=CSV FIELD_OPTIONALLY_ENCLOSED_BY='"' SKIP_HEADER=1)
ON_ERROR=CONTINUE;

How to Migrate from Oracle to Snowflake in PostgreSQL Syntax


COPY INTO <table_name>
FROM @<stage>/<path>
[FILES = ('file1','file2',...)]
FILE_FORMAT = (
  TYPE = CSV
  [FIELD_OPTIONALLY_ENCLOSED_BY = '"']
  [SKIP_HEADER = 1]
)
ON_ERROR = { ABORT_STATEMENT | CONTINUE | SKIP_FILE }
PURGE = TRUE|FALSE;

Example for ecommerce Orders table:
COPY INTO Orders (id, customer_id, order_date, total_amount)
FROM @oracle_migration/orders
FILE_FORMAT=(TYPE=CSV FIELD_OPTIONALLY_ENCLOSED_BY='"' SKIP_HEADER=1)
ON_ERROR=CONTINUE;

Common Mistakes

Ignoring data-type mismatches: mapping Oracle NUMBER(38,0) to Snowflake FLOAT causes rounding. Fix by casting to NUMBER or BIGINT during load.
Skipping FIELD_OPTIONALLY_ENCLOSED_BY in COPY INTO: commas inside text columns break row boundaries. Always match file delimiters and enclosures.

Frequently Asked Questions (FAQs)

Can I keep Oracle running during migration?

Yes. Perform full loads first, then incremental exports to minimize downtime before final cut-over.

Does Snowflake support Oracle sequences?

Snowflake uses IDENTITY columns. Convert sequences to IDENTITY or manage keys in application logic.

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