Best Practices for Running PostgreSQL on AWS - DAT314 - re:Invent 2017

© 2017, Amazon Web Services, Inc. or its Affiliates. All rights reserved.
Best Practices for Running PostgreSQL
on AWS
Jignesh Shah
S r . P r o d u c t M a n a g e r , A m a z o n R D S P o s t g r e S Q L
AWS re:INVENT
D e c e m b e r 1 , 2 0 1 7

PostgreSQL—Open Source Database
• Open source database
• In active development for 20 years
• Owned by a foundation, not a single company
• Permissive innovation-friendly open source license
• High performance out of the box
• Object-oriented and ANSI-SQL:2008 compatible
• Most geospatial features of any open source database
• Supports stored procedures in 12 languages (Java, Perl,
Python, Ruby, Tcl, C/C++, its own Oracle-like PL/pgSQL, etc.)
• Most Oracle-compatible open source databases
• Highest AWS Schema Conversion Tool automatic conversion
rates are from Oracle to PostgreSQL

PostgreSQL—Key Features
• SQL support
• Clustered indexes
• Flexible datatypes
• Parallel queries
• Parallel DML
• Window and custom functions
• Transaction control in Stored Procedure
• Custom languages
• Extensions

PostgreSQL Deployment Options
On-Premises Hosted Managed
EC2 DB Services

On-Premise PostgreSQL Deployment
Power, HVAC, net
Rack and stack
Server maintenance
OS patches
DB s/w patches
Database backups
Scaling
High availability
DB s/w installs
OS installation
you
App optimization

Hosting PostgreSQL on Amazon EC2
Power, HVAC, net
Rack and stack
Server maintenance
OS patches
DB s/w patches
Database backups
Scaling
High availability
DB s/w installs
OS installation
you
App optimization

Managed PostgreSQL on AWS
Power, HVAC, net
Rack and stack
Server maintenance
OS patches
DB s/w patches
Database backups
App optimization
High availability
DB s/w installs
OS installation
you
Scaling

Security and Compliance
• Network isolation
• Database instance IP firewall
protection
• AWS IAM-based resource-level
permission controls
• Encryption at rest using AWS KMS or
Oracle/Microsoft TDE
• SSL protection for data in transit
• Assurance programs for finance,
healthcare, government, and more

Amazon Virtual Private Cloud (Amazon VPC)
Securely control network configuration
Availability Zone
AWS Region
10.1.0.0/16
10.1.1.0/24
Manage connectivity
AWS Direct
Connect
VPN
connection
VPC
peering
Internet
gateway
Routing
rules

IAM-Governed Access
Use AWS Identity and Access Management (IAM) to control who can perform
actions on Amazon RDS
Users and DBAApplications DBA and Ops
Your database RDS
Controlled with IAMControlled with database grants

At-Rest Encryption
Two-tiered key hierarchy using envelope encryption
• Unique data key encrypts customer data
• AWS KMS master keys encrypt data keys
• Available for all RDS engines
Benefits:
• Limits risk of compromised data key
• Better performance for encrypting large
data
• Easier to manage small number of master
keys than millions of data keys
• Centralized access and audit of key activity
Leveraging AWS Key Management Service (AWS KMS)
Data key 1 Data key 2 Data key 3 Data key 4
Customer master
key(s)
Amazon
RDS
instance 3
Amazon
RDS
instance 2
Amazon
RDS
instance 1

Compliance
Singapore MTCS
27001/9001
27017/27018

Effortless Scaling
Scale compute/memory vertically up or down
Handle higher load to grow over time
Lower usage to control costs
6 TB

Backup and Disaster Recovery

Availability—Read and Write—Multi-AZ
Physical
Synchronous
Replication
AZ1 AZ2
DNS
cname update
Primary Update

Read Replicas
• Relieve pressure on your master node
with additional read capacity
• Bring data close to your applications
in different regions
• Promote a read replica to a master for
faster recovery in the event of
disaster

Read Replicas = Availability
Sync
Replication
Multi-AZ
Async Replication

Cross Region Replicas—Reduce Latency
AZ1 AZ2 AZ1
Async Replication
US-EAST-1 EU-WEST-1

Cross Region Replicas—DR & Moves
AZ1 AZ2 AZ1
Async Replication
US-EAST-1 EU-WEST-1 EU-WEST-1
AZ2

Major Version Upgrade
Prod
9.5
Prod
9.6
pg_upgrade
Backup Backup
No PITR
Test
9.5
Test
9.6
pg_upgrade
Restore to a test instance
Application
Testing

Upgrade with Minimum Downtime Using DMS
Start a replication instance
Connect to source and target databases
Select tables, schemas, or databases
RDS PostgreSQL 9.4
Application Users
RDS PostgreSQL 9.6
Let the AWS Database Migration
Service create tables and load data
Uses change data capture to keep
them in sync
Switch applications over to the
target at your convenience
AWS Database
Migration Service

Logical Replication Support
• Supported with 9.6.1+, 9.5.4+ and 9.4.9+
• Set rds.logical_replication parameter to 1
• As user who has rds_replication and rds_superuser role
SELECT * FROM pg_create_logical_replication_slot('test_slot',
'test_decoding');
pg_recvlogical -d postgres --slot test_slot -U master --host $rds_hostname -f -
--start
• Support for event triggers
RDS
Postgres
RDS
Postgres
Logical
Replica
Redshift
EC2
Postgres
On
Premise
Postgres
DMS
RDS/Aurora
PostgreSQL
Custom
Logical
Handler
NoSQL
DB

Amazon RDS for PostgreSQL
Supporting Latest Minor Releases
• 9.6.5
• 9.5.9
• 9.4.14
• 9.3.19
Next Major release—PostgreSQL 10

Notable Features
Support HugePages for RDS PostgreSQL
• Provides performance benefit for large instances
Stop and start of RDS PostgreSQL instances
New regions supported for RDS PostgreSQL
• China
• Brazil
Support encryption at rest for
• T2 small/medium
• Cross-region Read Replicas
Flexible RI

PostgreSQL Extensions/Modules Supported
rds-postgres-extensions-request@amazon.com
9.3 Original—32
9.3 Current—35
9.4 Current—39
9.5 Current—46
Future—???
9.6 Current—57

New PostgreSQL Extensions Supported
Extensions Description
pgrouting Provides geospatial routing functionality for PostGIS
postgresql-hll HyperLogLog data type support
decoder_raw Output plugin to generates raw queries for logical replication changes
pg_repack Remove bloat from tables and indexes in version 9.6.3
pgaudit Provide detailed session and object audit logging in versions 9.6.3 and 9.5.7
wal2json Output plugin for logical decoding in versions 9.6.3 and 9.5.7
auto_explain Log execution plans of slow statements automatically in versions 9.6.3 and 9.5.7
pg_hint_plan Provides control of execution plans by using hint phrases
log_fdw Extension to query your database engine logs within the database
pg_freespacemap Examine free space map

Extension—pgaudit (9.6.3+)
• CREATE ROLE rds_pgaudit
• Add pgaudit to shared_preload_libraries and pgaudit.role = rds_pgaudit in a
custom parameter group in PostgreSQL 9.6 family
• Apply the modified parameter group to 9.6.3+ database instance and apply immediately
• CREATE EXTENSION pgaudit
• Grant SELECT on all tables to rds_pgaudit to enable auditing
• GRANT SELECT ON t1 TO rds_pgaudit;
• Database logs will show entry as follows
• ... 2017-06-12 19:09:49 UTC:…:pgadmin@postgres:[11701]:LOG: AUDIT:
OBJECT,1,1,READ,SELECT,TABLE,public.t1,select * from t1; ...

Extension—pg_stat_statements
CREATE EXTENSION pg_stat_statements
SELECT * from pg_stat_statements order by total_time DESC;
-[ RECORD 2 ]-------+--------
userid | 16388
dbid | 16464
queryid | 4286627671
query | UPDATE pgbench_accounts SET abalance = abalance + ? WHERE aid = ?;
calls | 165125
total_time | 5251.54200000001
min_time | 0.015
max_time | 5.558
mean_time | 0.0318034337623008
stddev_time | 0.0369181019548524
rows | 165125
SELECT substring(query, 1, 50) AS short_query,
round(total_time::numeric, 2) AS total_time, calls,
round(mean_time::numeric, 2) AS mean, round((100 * total_time
/sum(total_time::numeric) OVER ())::numeric, 2) AS percentage_cpu FROM
pg_stat_statements ORDER BY total_time DESC LIMIT 10;

Use DB Parameter Groups
Create a basic template for all your
deployments with
rds.force_ssl=true
shared_preload_libraries=pgaudit,
auto_explain,pg_stat_statements,pg_re
pack
pgaudit.role = rds_pgaudit
huge_pages = on
Use basic template or copy to instance-
specific parameter group
Avoid typos while editing parameters

Optimizing PostgreSQL Parameters
Most instances have a default calculated shared_buffers
• Typically 25% of RAM
For high active connections require free memory
• First make sure huge_pages = on
• Reduce shared_bufferpool if required
Increase maintenance_work_mem as required
Right size work_mem based on typical sort performances
• Impact is per connection
For high load write transactions
• max_wal_size = 1024 (MB)

Cloud-optimized relational database
Performance and availability of
commercial databases
Simplicity and cost effectiveness of
open source databases,
now with PostgreSQL compatibility
What Is Amazon Aurora?

A S e r v i c e - O r i e n t e d A r c h i t e c t u r e A p p l i e d t o t h e D a t a b a s e
Move the logging and storage layer into a
multitenant, scale-out, database-optimized
storage service.
Integrate with other AWS services like
Amazon EC2, Amazon VPC, Amazon
DynamoDB, Amazon SWF, and Amazon
Route 53 for control and monitoring.
Make it a managed service—using Amazon
RDS. Takes care of management and
administrative functions.
Amazon
DynamoDB
Amazon
SWF
Amazon
Route 53
Logging + Storage
SQL
Transactions
Caching
Amazon S3
1
2
3
Amazon
RDS

PostgreSQL 9.6 + Amazon Aurora cloud-optimized storage
§ Performance: 2x–3x higher throughput than PostgreSQL alone
§ Availability: failover time of <30 seconds
§ Durability: six copies across three Availability Zones
§ Read Replicas: single-digit millisecond lag times on up to 15 replicas
Amazon Aurora Storage
Aurora PostgreSQL

Amazon Aurora Storage Engine Overview
Data is replicated six times across three Availability
Zones
Continuous backup to Amazon S3 (built for 11 9s
durability)
Continuous monitoring of nodes and disks for repair
10 GB segments as unit of repair or hotspot
rebalance
Quorum system for read/write; latency tolerant
Quorum membership changes do not stall writes
Storage volume automatically grows up to 64 TB
AZ 1 AZ 2 AZ 3
Amazon S3
Database
Node
Storage
Node
Storage
Node
Storage
Node
Storage
Node
Storage
Node
Storage
Node
Storage
Monitoring

RDS/Aurora PostgreSQL Monitoring
Amazon CloudWatch metrics
• CPU utilization
• Storage
• Memory
• Swap usage
• DB connections
• I/O (read and write)
• Latency (read and write)
• Throughput (read and write)
• Replica lag
Amazon CloudWatch alarms
• Similar to on-premises monitoring tools
Enhanced Monitoring for Amazon RDS
• Access to over 50 CPU, memory, file
system, and disk I/O metrics
• Low as 1 second intervals
Integration with third-party monitoring tools

Performance Insight: Simplifying Monitoring
• Dashboard displaying load on
database
• Easy
• Powerful
• Identifies source of
bottlenecks
• Top SQL
• Adjustable time frame
• Hour, day, week, month
• Up to 35 days of data
Max CPU

PostgreSQL Events and Logs

CloudWatch Metric—Max Used Trans IDs

Avoiding Transaction ID Wraparound
Two billion “in-flight” un-vacuumed transactions before PostgreSQL takes
dramatic action to avoid data loss
If the number of un-vacuumed transactions reaches (2^31 – 1,000,000):
• PostgreSQL sets the database to read-only mode and requires an
offline, single-user, standalone vacuum
VACUUM (non blocking) records free space into .fsm files
VACUUM FULL (blocking) shrinks the size of the database disk files

AUTOVACUUM Tuning
For 24/7 constant load on database server
• AUTOVACUUM may not get a chance to finish its job
For high number of tables
• Increase autovacuum_max_workers from default 3 to higher number
• Increase autovacuum_vacuum_cost_limit
• Note: With this change there may be performance impact
For large tables use
• Decrease autovacuum_vacuum_scale_factor from 0.2 (20%) to 0.05
(5%)
• ALTER TABLE myablename SET autovacuum_scale_factor = 0.02

Extension—pg_repack (9.6.3+)
• Add pg_repack to shared_preload_libraries in a custom parameter group
in PostgreSQL 9.6 family
• Apply the modified parameter group to 9.6.3+ database instance and apply
immediately
• CREATE EXTENSION pg_repack
• Use pg_repack client utility using rds_superuser privileges with –k option
• pg_repack -h myproductiondb.cw7jjfgdr4on8.us-west-
2.rds.amazonaws.com -U pgadmin -k postgres

CloudWatch—Replication Lag

Read Replica Lag
Increase wal_keep_segments to allow replicas to catch up after
interruption
Use wal_compression = on
Use higher checkpoint_timeout
Lag for replicas vs long running queries on replicas
• max_standby_archive_delay
• max_standby_streaming_delay
Use hot_standby_feedback = on on Read Replicas
Use similar sized instance size (or larger)

Amazon RDS PostgreSQL Customers

Thank you!

Best Practices for Running PostgreSQL on AWS - DAT314 - re:Invent 2017

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Best Practices for Running PostgreSQL on AWS - DAT314 - re:Invent 2017