Comparison: Aurora PostgreSQL vs Oracle

Modified date: Monday, June 30, 2025

Introduction
General
Data Types
SQL
Storage and System
Benchmarking
Tools
Export Regulations
Internal
Internal - Optimizer
Internal - Runtime
Internal - Storage Engine

General

Feature	Aurora PostgreSQL	Oracle	Definition
intro	Aurora is a relational database management system (RDBMS) built for the cloud with full MySQL and PostgreSQL compatibility.	Oracle Database is a DBMS developed by Oracle Corporation.	in their own words - but I reserved the rights to remove some bold claims like "the best", unless it is widely recognized.
vendor	Amazon AWS	Oracle
initial release		1980
latested version		23ai	We don't put a release date here as the software is patching frequently. So tracking it is not much useful.
supported platforms		Windows, Linux, Solaris, HP-UX, AIX, z/OS	supported OS/CPU platforms
db-engines ranking		1	ranks from https://db-engines.com/en/ranking (06/25)
relational?		yes Oracle also has an open source nosql database.	Is it a relational database? (1) Most database are actually with some extensions, for example, nested data types, graph support, etc, which we usually called "multi-model". (2) Some of them are product family, meaning they have more than one database. Here we focus on the main one but explain others when needed.
open source?		no	mainly the engine code
license		commercial
on-premise offering		yes	if no means you can't buy "box" software from them
cloud offering		Oracle Cloud and other cloud vendors
technical doc		https://docs.oracle.com/en/database/

Data Types

Feature	Aurora PostgreSQL	Oracle	Definition
int: signess	signed only		if differentiate signed and unsigned int
int: 1-bytes int name	n.a.
int: 2-bytes int name	smallint
int: 3-bytes int name	n.a.
int: 4-bytes int name	int	int
int: 8-bytes int name	bigint
decimal: storage size	variable
decimal: range	up to 131072 digits before the decimal point; up to 16383 digits after the decimal point		also called number, numeric in different systems
char(n): max bytes	10,485,760	2000
text: max bytes	1G
BLOB: max size		(4B-1) * pages Page size is defined by DB_BLOCK_SIZE in Oracle, which is ranging from 2K to 32K. This gives BLOB size from 8T to 128TB.
JSON: max size		32MB
Literal: max size		4000	characters or numbers in SQL or PL/SQL

SQL

Feature	Aurora PostgreSQL	Oracle	Definition
base	PostgreSQL
SQL: standard complaince	high	high
max SQL length	undefined same as PostgreSQL with "StringInfo" container	undefined The actual limit may depends on limits of the SUT, for example, its memory/system swap settings: Oracle internally must use a malloc'ed buffer to hold the SQL string.	maximal SQL statement length
PL: main	SQL + PL/PgSQL	SQL + PL/SQL	main programming lanage: most database suports SQL because SQL is a well established standard. However, each database would like to extend SQL more or less.
PL: other language support	yes	yes	PL lanaguage other than PL/SQL, like PL/Java, PL/Rust etc
SP: max parameters	100
UDF: max parameters	100
SQL: max parameters	65535		number of parameters in a PREPARED query
SQL: query hints	GUC only	complete	if it allows use query hints to guide the optimizer
SQL: explicit locking	yes: row, page, table level	yes	Locking is usually an internal matter - so does it allow explicit locking? What levels do they support?
Triggers?	yes	yes	If support triggers
Triggers: scope	tables, views, foreign tables		What objects can have triggers
Triggers: type	BEFORE, AFTER, INSTEAD OF		Types of triggers supported
Object-Relational?	yes	some
Extension Mechanism	C programming, link with engine
vector search	no native		does it support vector search

Storage and System

Feature	Oracle	Definition
arch: server	C/S Oracle has a family of databases, even with nonsql one.	Embedded or traditional C/S?
arch: run in browser?	no	It also known as a client-side database, is a database that is stored and managed within a user's web browser, rather than on a remote server.
arch: clustering/HA	RAC, Data Guard
arch: in-memory support	Oracle Database In-Memory option
arch: Multi-master support?	yes	if multi-master support?
arch: primary/read replica?	yes	if primary + mulitiple read replica supported
replication: sync/async	both	Can commits wait or w/o wait for replicas to acknowledge
replication: WAL shipping	yes	Uses write-ahead log (WAL) shipping for replication
sessions: max	262143
tables: max number per database	undefined
tables: max number of columns	4096	Max number of columns per table
contraints: max per column	undefined
partitions: methods	Range, List, Hash, Composite (sub-partitions supported).	Supported partitioning strategies (range, list, hash, etc.).
partitions: global index	yes	index across partitions
constraints: max per database	4,294,967,293
rows: max rows per table	undefined	The actual number depends on storage etc
index: max allowed index	undefined	Max number of indices allowed per table
index: max allowable size	6400	Max index record size (bytes). This constraint is mainly coming from the fact of the database page size: if we exclude blob data types, database engine usally do not allow a record expand more than one page.
index: max number of fields	32	Max number of columns allowed in one index
partition: max allowed partitions	1M-1	Meta data challenge: 1M partitions just like 1M tables, system have to hold them in memory. Optimizer challenge: O(N) algorithm may lead to very long planning time if there are excessive partitions.
partition: max allowed key columns	16
partition: max number of subpartitions	1M-1
ACID	yes/yes	for DML and DDL
ACID: max isolation level	SI The Snapshot Isolation (SI) implemented by Oracle allows some anomalies, including write skew. But the SI does satisfies ANSI's serializable definition.
ACID: max ANSI isolation level	Serializable
ACID: durability	yes
Materialized View: support?	yes

Benchmarking

Feature	Oracle	Definition
any official TPC benchmarks?	yes	The TPC benchmark includes a set of tests simulating real-world scenarios to evaluate database performance.
TPCC: most recent tpmC	8,552,523 System cost: 4,663,073 USD
TPCC: most recent submit date	3/26/2013
TPCC: most recent per thread perf	8352
TPCC: best tpmC	30,249,688 System cost: 30,528,863 USD
TPCC: best perf submit date	12/2/2010
TPCC: best perf per thread perf	2188

Tools

Feature	Aurora PostgreSQL	Oracle	Definition

Export Regulations

Feature	Oracle	Definition
Jurisdiction	US	Which country controls export
ECCN	5D992.c	An Export Control Classification Number (ECCN) is a five-character alphanumeric code used to categorize items on the Commerce Control List (CCL) for export control purposes. Most database may fall into 5D992.c category, "mass market encryption", which means it has some ordinary encryption related code, for example, the SSL connection code.
Eligible License Exception / CCATS	NLR NLR essentially means that a commodity has been classified within the Commodity Classification Automated Tracking System and determined to not require a BIS export license for its export.	A License Exception is an authorization that allows you to export or reexport items subject to the EAR without needing to obtain a specific export license, provided certain conditions are met. CCATS stands for Commodity Classification Automated Tracking System. The BIS assigns a CCATS number to products that it has classified under the Commerce Control List (CCL).
Encryption Components	TDE, SSL	Crypto functionality that triggers control

Internal

Feature	Oracle	Definition
concurrency control	MVCC
MVCC: implemented?	yes	if implement MVCC for concurrency control
MVCC: rollback segment	yes	if uses rollback segment (RS) to store old versions. Without RS, old versions and new versions are mixed stored, then the database engine has to find a way to efficiently drop the old versions at certain point.
Implementation language	C	A DBMS may use mulitple programming languages, for example, supports its stored procedure. The major programming language used to implement the engine.

Internal - Optimizer

Feature	Oracle	Definition
CBO?	yes	if it employees a cost based optimizer
framework	System-R	System-R is more like a dynamic programming, bottom up optimizer, while Cascades/Volcano gebaseerd optimizer is more like top-down optimizer.
query hints?	complete	if it allows use query hints to guide the optimizer

Internal - Runtime

Feature	Oracle	Definition
resource management	complete	How execution memory is allocated and limited.
support intra-parallel query?	yes	meaning a single query can utilize multi hardware threads to run it
vectorization	yes	Speed up OLAP queries using vectorized execution. A vectorized runtime exchange a bunch of rows between iterators, and these rows are physically sotre with column-oriented order.
iterator: join methods	all 3	Hash Join (HJ), Sort-Merge Join (MJ) and Nested loop Join (NLJ) are 3 major ones

Internal - Storage Engine

Feature	Oracle	Definition
Page Size	2K-32K	The physical disk block size for storage and I/O.
partition table	complete	Partitioning capabilities for large tables.
partition table: prunning	both	Ability to eliminate partitions at query compile time and runtime
ACID: durability mechanism	WAL	How is it implements durability. Database's classic way is write ahead logging (WAL).

Comparison: Aurora PostgreSQL vs Oracle

Table of Contents

General

Data Types

SQL

Storage and System

Benchmarking

Tools

Export Regulations

Internal

Internal - Optimizer

Internal - Runtime

Internal - Storage Engine