Learn and leverage database migration best practices from moving off commercial Oracle databases to Amazon RDS or Aurora. We’ll cover common pitfalls, issues, the biggest differences between the engines, migration best practices, and how some of our customers have completed these migrations.

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Shailesh Rangani, Cloud Database Engineer, Datavail
Lessons from Migrating
Oracle Databases to Amazon
RDS or Amazon Aurora

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Shailesh Rangani
• Shailesh Rangani is a Cloud Database Engineer with 15
years’ experience in database domain.
• He holds various certifications on cloud platforms like
AWS, Azure and OCI along with database platforms like
PostgreSQL, MongoDB, Oracle and DB2 LUW.
• He is an expert in the design, deployment,
administration, and management of data-intensive
applications that enable organizations to effectively
analyze and process large volumes of structured and
unstructured data.
• Shailesh specializes in Cloud platforms and DBMS
technologies. He has successfully delivered the data
architecture strategy for projects and large-scale
platforms.
Shailesh Rangani
Cloud Database Engineer, Datavail

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About Datavail
Databases
• Oracle
• SQL Server
• MySQL
• MariaDB
• PostgreSQL
• Cassandra
• MongoDB 100+ Cloud SA’s
and Engineers
16+ Years
Database Services
700+ Customers
8+ Years AWS
Cloud Experience
200,000+
Databases Managed
150+ AWS
Migrations and
Modernizations
Expertise Experience Outcome
Analytics and Data
Integration

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• Why break free? The business case for
moving to AWS databases
• Common migration paths to
modernization
• Introduction to Amazon Aurora
• Database migration
• Best practices
• Hands on lab (Oracle to Aurora PostgreSQL)
Agenda

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Flexible Ways to Break Free

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A typical database migration lifecycle
Data
migration
Application
code
Schema
objects
Cutover
Analysis
Testing

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We offer flexible ways to help you migrate
AWS Migration
Tools
AWS ProServe and
Migration Partners
AWS Database
Freedom Program

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Flexible, powerful migration tooling
Most sources and targets, higher conversion automation
Source DB or DW AWS SCT Destination DB or DW
Source DB or DW Destination DB or DWAWS DMS
Copy or convert
Data
schema
Step 1: Convert or copy your schema
Step 2: Move your data

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AcceleratedAmazon Aurora Migration
Case Study 1 – Midsized Utility Firm
• Single monolithic DB
• Lot of historical data
• Oracle licensing cost
• Encryption (TDE)
• Scalability
• Credential rotation
• Quick testing environment
• Native utilities for static
data migration
• AWS Database Migration
Service (DMS) & AWS
Schema ConversionTool
• Databases runningAurora
PostgreSQL
• Encryption via KMS
• Auto Scaling (CPU based)
• Native partitions
• Database clone for quick
test environment
Challenges Accelerated Migration Outcome
AWS Schema
ConversionTool
AWS Database
Migration Service
Oracle instance Aurora PostgreSQL

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Case Study 2 – Midsized Financial Company
• Oracle licensing cost
• Multiple Sources
• Heavy read intensive workload
over weekend
• 150,000 lines of code to convert
• 3000 + objects to convert
• AWS Database Migration
Service (DMS) & AWS Schema
ConversionTool
• Expert PostgreSQL
developers/AWS SA
• Code conversion 2 months
• RegressingTesting
• Databases runningAurora
PostgreSQL
• Faster reports
• Lower licensing costs
• IAM authentication at DB level
• DB code moved to app layer
• Auto Scaling (scheduled
based)
Challenges Accelerated Migration Outcome
AcceleratedAmazon Aurora Migration
AWS Schema
ConversionTool
AWS Database
Migration Service
Oracle instance Aurora PostgreSQL

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Introduction to Amazon Aurora

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Benefits of Amazon Aurora
AmazonAurora
Speed and availability of high-end commercial databases
Simplicity and cost-effectiveness of open source
databases
Drop-in compatibility with MySQL and PostgreSQL
Simple pay as you go pricing
So, we designed Amazon Aurora - enterprise database at open source price,
delivered as a managed service

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Scale-out, distributed, multi-tenant storage architecture
• Purpose-built log-
structured distributed
storage
• Storage volume is striped
across hundreds of
storage nodes
• Storage nodes with locally
attached SSDs
• Continuous backup to
Amazon S3. AZ 1 AZ 2 AZ 3
SHAREDCLUSTER STORAGEVOLUME
Writer
Transactions
Caching
SQL
Cluster
Endpoint
Amazon S3
Reader
Transactions
Caching
SQL
Reader
Transactions
Caching
SQL
Reader
Endpoin
t

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Leverages the AWS Cloud ecosystem
AWS Lambda Amazon S3 AWS IAM
Amazon
CloudWatch
Invoke AWS Lambda events
from stored
procedures/triggers
Load from, save to Amazon
S3, store snapshots and
backups in S3
Use AWS Identity &
Access Management
(IAM) roles to manage
database access control
Upload systems metrics and audit logs to
Amazon CloudWatch
Amazon Sagemaker
Amazon Comprehend
Make inferences directly from your database
using SQL calls

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Automates administrative tasks
Schema design
Query construction
Query optimization
Automatic fail-over
Backup & recovery
Isolation & security
Industry compliance
Push-button scaling
Automated patching
Advanced monitoring
Routine maintenance
Takes care of your time-
consuming database
management tasks, freeing you
to focus on your applications and
business
YOU
AWS

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Who is adopting Amazon Aurora?
• Higher performance
• Better availability
and durability
• Easy migration; no
application change
• One-tenth of the
cost; no licenses
• Comparable
performance and
availability
• Migration tooling and
services
• Integration with
other
AWS services
• Cloud-native
capabilities and
access
mechanisms
• Scalability,
availability,
managed service
Customers migrating from
open source PostgreSQL
Customers using
commercial DB engines
Customers building new
applications

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Schema Conversion

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AWS Schema ConversionTool
• Assessment report
• Project interface
• Code browser
• Automates many conversion tasks
Packages
Stored procedures
Functions
Triggers
User defined types
Schemas
Tables
Indexes
Views
Sequences
Synonyms
Tab with the assessment report Manual conversion tips
Side by side code view

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AWS Schema Conversion Tool tips
Save as an SQL file
• Allows you to apply only
Table DDL & PK
• Save the secondary DDL for
after migration
Memory management
• Global settings
• JVM settings

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SCT migration assessment report
Connect SCT to “source”
& “target”
Run “assessment report”
Read “executive
summary” & follow
detailed instructions
More: https://docs.aws.amazon.com/SchemaConversionTool/latest/userguide/CHAP_AssessmentReport.Create.html

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SQL scripts
Packages
Stored procedures
Functions
Triggers
User defined types
Schemas
Tables
Indexes
Views
Sequences
Synonyms
SCT does a great job of converting
your schema and code objects
Users, roles, grants
https://aws.amazon.com/blogs/database/use-sql-to-map-users-roles-and-grants-from-oracle-to-postgresql/

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Oracle to Amazon
Aurora PostgreSQL
Migration Playbook –
Example
More:
https://d1.awsstatic.com/whitepapers/Migration/oracle-
database-amazon-aurora-postgresql-migration-
playbook.pdf

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Data Migration

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Move Data using Data Migration Service
Oracle Databases AWS Database
Migration Service
Amazon Aurora
AWS DMS Replication
Instances
AWS DMS
ReplicationTasks
Read Write

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Support for the following conversions
Source* Database Target* Database on AWS
Oracle database Amazon Aurora, MySQL, PostgreSQL, Oracle
Oracle data warehouse Amazon Redshift
Azure SQL Amazon Aurora, MySQL, PostgreSQL
Microsoft SQL Server Amazon Aurora, Amazon Redshift, MySQL PostgreSQL
Teradata Amazon Redshift
IBM Netezza Amazon Redshift
Greenplum Amazon Redshift
HPEVertica Amazon Redshift
MySQL and Maria DB PostgreSQL
PostgreSQL Amazon Aurora, MySQL
Amazon Aurora PostgreSQL
IBM DB2 LUW Amazon Aurora, MySQL, PostgreSQL
Apache Cassandra Amazon DynamoDB
Source: https://docs.aws.amazon.com/dms/latest/userguide/CHAP_Source.html Target: https://docs.aws.amazon.com/dms/latest/userguide/CHAP_Target.html

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AWS Database Migration Service
Working with DMS components
• Replication Instance
‒ C - compute R - memory T - burstable
• Endpoint
‒ Connect source / target from replication instance
‒ Choose advanced override settings
• Task
‒ Full Load
‒ Change Data Capture

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AWS Database Migration Service
Best Practices choosing a replication instance
• How to choose between different instance types.
• Things to know about EBS storage on replication instance
• Important Amazon CloudWatch metrics to watch on the replication
instance

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AWS Database Migration Service
Best Practices Designing the source & target endpoint
• Oracle (source)
‒ When to use ‘binary reader’
‒ When to use ‘log miner’
‒ Using NumberDataTypeScale
‒ Using standbyDelayTime
• Aurora PostgreSQL (target)
‒ Using ‘maxFileSize’

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AWS Database Migration Service
Components of a DMS task
• Choosing a “migration type”
‒ Full Load
‒ Change Data Capture (CDC)
• Choosing a target table prep mode
‒ DMS can create tables, however, better pre-create table with SCT
‒ Flexibility to drop or truncate tables.
• Include LOB columns in replication
‒ Why limited LOB (Large Object) mode is a better choice?
• Selection & transformation rules, logging, exceptions, and others
‒ Flexible in selection but limited transformations
‒ How to work around transformations

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Task – Migration type
Choose migration
type
Existing data
Existing data
and replicate
changes
Replicate
changes only
Creates files or tables in the target database
Populates the tables with data from the source
Migrate existing data option in the AWS console and Full Load in the API
Captures changes on the source during migration
Once initial migration completes, changes are applied to the target as units of
completed transactions
Migrate existing data and replicate ongoing changes option in the AWS console
and full-load-and-cdc in the API.
Reads the recovery file on the source database
Groups together transactions and applies them to the target. Buffering as needed
Replicate data changes only option in the AWS console

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Task – Target preparation
Target
preparation
Do nothing
Drop tables on
target
Truncate
In Do nothing mode, AWS DMS assumes target tables are pre-created.
In full load or full load plus CDC, ensure that the target tables are empty
before starting the migration.
In Drop tables on target mode, AWS DMS drops the target tables and
recreates them before starting the migration.This ensures that the target
tables are empty when the migration starts.
In Truncate mode, AWS DMS truncates all target tables before
the migration starts.

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Task – Include LOBs
Include LOBs
Don't include
LOBs
Full LOB
mode
Limited LOB
mode*
LOB columns are excluded from the migration.
Migrate complete LOBs regardless of size.AWS DMS migrates LOBs
piecewise in chunks controlled by the Max LOB size parameter.This mode
is slower than using Limited LOB mode.
Truncate LOBs to the value of the Max LOB size parameter.This mode
is faster than using Full LOB mode.

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Task – Selection and Transformation rules

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AWS Database Migration Service
AWS Cloud
VPCCustomer On-premises
VPN
Oracle Aurora
PostgreSQL
DMS Replication
Instance
Application users
• Start a replication instance
• Connect the source and target endpoints
• DMS FULL LOAD the data from Source to
Target• DMS Change Data Capture to replicate
ongoing changes
• At steady state – take an outage, validate &
redirect connection
End Point Connection
Full Load
Change Data
Capture

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Best Practices for Production
Rollout

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PostgreSQL is a lowercase
data dictionary
Use “exception handlers”
when needed, not by default
PostgreSQL has six
different index types.
Store your BLOBs in
Amazon S3 instead of the
database
search_path replaces
PUBLIC SYNONYM
PostgreSQL
has 64 datatypes
Understand basic database engine differences

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Overview of migration steps

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Start full load
Source TargetReplication
Instance

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While loading data also capture changes
Source TargetReplication
Instance
App

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Load complete - apply captured changes
Source TargetReplication
Instance
App

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Changes reach steady state
Source TargetReplication
Instance
App

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Shutdown apps and apply remaining changes
Source TargetReplication
Instance
App

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Change your application endpoint
Source TargetReplication
Instance
App

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Fill Out Cloud
Adoption
Industry
Benchmark
Survey
Fill out the survey for a chance to WIN
a pair of our cool Bose noise cancelling
headphones!
https://www.datavail.com/cloud-survey/

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Workshop Architecture

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DMS Workshop - Instructions for Hands-on Lab
• Workshop Instructions https://dms-immersionday.workshop.aws/en/oracle-aurora.html
• Account Access: https://dashboard.eventengine.run
• Region – US-West-2 (Oregon)

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Lab Architecture
VPC
AWS Cloud
Windows
Remote Desktop
User
Amazon EC2
AWS Schema Conversion
Tool (SCT)
Source
Amazon RDS
(Oracle)
AWS Database
Migration Service
Target
Amazon Aurora
RDS (PostgreSQL)

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Lab Instructions
Part 1: (Approx. time 1 hour)
• Remote desktop to EC2
• Install Schema Conversion Tool (SCT)
• Create a SCT project
• Convert the Oracle Schema
Part 2: (Approx. time 1hour 30
min)
• Connect to Source (Oracle) and
configure DMS access
• Connect to Target (Aurora PG) and
prepare for DMS load
• Create Replication Instance
• Create Source and Target
Endpoints
• Create DMS Task
• Verify the data

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Appendix

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Migrate & Modernize Your Databases with Datavail &
AWS
• Break free from commercial databases with migrations and modernizations to
the AWS Cloud with Datavail as your trusted partner.
• Contact us to learn more about our AWS Cloud capabilities and to set up a
discovery workshop at no cost.
• Additional Datavail resources:
• Transition from Commercial Databases to Amazon Web Services
• AWS Database Migration Jump Start for Aurora
• 10 Best Practices to Secure PostgreSQL AWS RDS/Aurora

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AWS Database Partners
Migration SI Partners License Advisory Partners

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Purpose-built Databases
aws.amazon.com/products/databases/
Database Migration Service
aws.amazon.com/dms/resources/
Database Freedom
aws.amazon.com/solutions/databasemigrations/database-freedom/
AWS Database Migration Partners
aws.amazon.com/dms/partners/
Migration Resources Library
aws.amazon.com/solutions/database-migrations/resources/
Other resources for you to leverage