How to Migrate from Oracle to BigQuery in PostgreSQL

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How do I migrate data, schemas, and SQL from Oracle to BigQuery without downtime?

Move schemas, data, and SQL logic from Oracle to Google BigQuery reliably and with minimal downtime.

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Why migrate Oracle data to BigQuery?

Reduce license cost, scale analytics, and integrate with Googles ecosystem.BigQuery offers serverless storage and pay-as-you-go compute.

What are the high-level steps?

1 Assess objects 2 Extract data 3 Transform DDL & SQL 4 Load into BigQuery 5 Validate 6 Cut over.

How do I assess Oracle objects quickly?

Run SELECT owner, object_type, COUNT(*) FROM dba_objects GROUP BY owner, object_type; then export CSV and prioritize tables, views, procedures.

Which extraction tool works best?

Oracles expdp with PARALLEL flag exports large tables faster.For change data capture (CDC), use Datastream.

How do I convert Oracle DDL to BigQuery?

Feed .dmp files to the ora2pg utility. It maps types (NUMBER NUMERIC, CLOB STRING) and generates BigQuery-compatible CREATE TABLE scripts.

What does a transformed CREATE TABLE look like?

CREATE TABLE ecommerce.customers (id INT64, name STRING, email STRING, created_at TIMESTAMP);

How do I stage data in Cloud Storage?

Use gsutil -m cp /dump/*.csv gs://oracle_exports/.BigQuery can load directly from GCS.

How do I bulk-load data?

Run bq load --source_format=CSV --replace --field_delimiter=',' ecommerce.customers gs://oracle_exports/customers.csv schema.json.

Can I automate continuous sync?

Create a Datastream -> Dataflow pipeline that streams Oracle redo logs into BigQuery in near real time.

How do I validate row counts?

Compare SELECT COUNT(*) FROM customers; in both systems.Differences should be zero before cutover.

What is the cut-over strategy?

Freeze writes in Oracle, apply final CDC batch, swap reporting apps to BigQuery, and archive the Oracle instance.

Best practice: partition & cluster BigQuery tables?

Partition by order_date and cluster by customer_id to cut query cost.

How to rewrite PL/SQL to BigQuery SQL?

Replace cursors with set-based queries and translate MERGE statements to BigQuerys MERGE INTO syntax.

Where to store reusable queries?

Use Galaxy Collections to share validated migration queries with your team and endorse them for future use.

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

How to Migrate from Oracle to BigQuery in PostgreSQL Example Usage


-- Migrate Orders table with daily partitioning
CREATE TABLE ecommerce.Orders (
  id INT64,
  customer_id INT64,
  order_date DATE,
  total_amount NUMERIC
) PARTITION BY DATE(order_date);

bq load --source_format=CSV \
        --time_partitioning_field=order_date \
        ecommerce.Orders \
        gs://oracle_exports/orders.csv \
        id:INT64,customer_id:INT64,order_date:DATE,total_amount:NUMERIC;

How to Migrate from Oracle to BigQuery in PostgreSQL Syntax


-- 1. Export Oracle tables to CSV
expdp system/password schemas=ECOMMERCE tables=CUSTOMERS,ORDERS dumpfile=ecom.dmp directory=DATA_PUMP_DIR

-- 2. Upload to Cloud Storage
gsutil -m cp customers.csv gs://oracle_exports/

-- 3. Create BigQuery tables matching Oracle structure
CREATE TABLE ecommerce.Customers (
  id INT64,
  name STRING,
  email STRING,
  created_at TIMESTAMP
);

-- 4. Load data
bq load --source_format=CSV \
        --field_delimiter="," \
        ecommerce.Customers \
        gs://oracle_exports/customers.csv \
        id:INT64,name:STRING,email:STRING,created_at:TIMESTAMP

-- 5. Verify counts
SELECT COUNT(*) FROM ecommerce.Customers;

Common Mistakes

Ignoring Oracle NUMBER precision causes truncation in BigQuery. Always map NUMBER(p,s) to NUMERIC(p,s) or BIGNUMERIC for high precision.
Loading huge CSVs without partitioning forces full-table scans. Define partitioning fields during CREATE TABLE or in the bq load command.

Frequently Asked Questions (FAQs)

Is BigQuery a drop-in replacement for Oracle?

No. BigQuery lacks row-level transactions and PL/SQL packages. Refactor procedural code to set-based queries or Cloud Functions.

How do I migrate sequences?

Replace Oracle sequences with BigQuery generated columns using GENERATE_UUID() or maintain counters in a separate table.

Can I keep Oracle as the source of truth?

Yes. Configure Datastream CDC into BigQuery for real-time analytics while OLTP traffic stays on Oracle.

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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