October 21, 2020 By Danny Arnold 5 min read

Part 1: A comparison of the two fully managed cloud data warehouse services.

There are many Oracle Database transactional and operational systems that exist in on-premises environments across thousands of clients. Many of these clients would like to perform analytics on their data to gain insights into their business and improve decision making to gain a competitive advantage.

Let’s look at Oracle Autonomous Data Warehouse (ADW) and IBM Db2 Warehouse on Cloud (WoC) to better understand both of these cloud data warehouses and explore which may be the best choice for cloud-based analytics processing of your Oracle Database transactional data.

To start our discussion of the best analytics platform for Oracle transactional data, let’s take a look at both the Db2 WoC and Oracle ADW managed data warehouse services to understand the various configurations and plans that are offered by IBM and Oracle.

What is IBM Db2 Warehouse on Cloud?

IBM Db2 Warehouse on Cloud (WoC) is IBM’s fully managed cloud data warehouse offering, and it consists of two primary configurations for larger data warehouse workloads:

  • Flex (for smaller data warehouses or those without performance requirements)
  • Flex Performance (for data warehouses with strict performance requirements)

All Db2 WoC Flex and Flex Performance base configurations provide a dedicated environment that includes cores, memory, and storage. Additional compute (cores and memory) and storage can be added in fixed increments, with compute and storage being independent of each other. Since Db2 WoC is based on the Db2 database engine and is optimized for data warehouse workloads, Db2 WoC provides Oracle compatibility. The Oracle compatibility allows Oracle clients to use Db2 WoC with Oracle Database SQL and PL/SQL, which allows them to continue to use their existing Oracle Database application development skills and not have to learn Db2-specific syntax for applications and queries executing on Db2 WoC.

What is Oracle Autonomous Data Warehouse?

Oracle Autonomous Data Warehouse (ADW) is comprised of Oracle Database Enterprise Edition (with all database options and management packs included from a software packaging perspective), Oracle Exadata X8M-2 as the primary deployment platform, and the Oracle Cloud Automated Database and Database Operations components (scripts, best practices, procedures, etc.) to make the database environment fully managed. 

Each Oracle Autonomous Data Warehouse database is actually an Oracle Pluggable Database (PDB) residing within an Oracle Exadata machine. There are two types of Oracle Autonomous Data Warehouse configurations that can be selected: 1) Autonomous Data Warehouse – Shared, and 2) Autonomous Data Warehouse – Dedicated.

With ADW-Shared, the only database resource that is dedicated are the Oracle CPUs (OCPUs). Database memory on the Exadata Database Servers and Flash Cache, Persistent Memory, and Storage on the Exadata Storage Servers are all “shared” resources and allocated across all PDBs that reside on that Oracle Exadata machine. This can lead to inconsistent data warehouse performance, as a client has no visibility into what other PDBs within the same Oracle Exadata machine are doing. In order to get consistent performance and dedicated database memory and Exadata Storage Server resources, Oracle ADW-Dedicated is the only option for clients. Oracle ADW-Dedicated is available in Exadata Quarter Rack, Half Rack, and Full Rack configurations.

Although Oracle ADW-Dedicated has an ongoing infrastructure cost, this infrastructure cost includes the Exadata Database Servers (memory only), Exadata Storage Servers (including storage capacity), all Oracle Linux, Oracle Database, and Exadata software ONLY. Oracle CPUs (OCPUs) for compute are NOT included in the infrastructure and are additional cost priced by the hour. The only growth options with Oracle ADW-Dedicated is to move to the next configuration “step” with Oracle Exadata if more OCPUs or storage capacity are required for the data warehouse. As an example, if a client has a subscription to Oracle ADW-Dedicated Quarter Rack and exceeds either the 96 database cores or 150 TB of storage capacity, the Oracle ADW-Dedicated PDB must be moved to an Exadata Half Rack configuration, which doubles the compute capacity (96 to 192 cores) and more than doubles the storage capacity (150 TB to 349 TB). Although the client can allocate database cores in increments of 4 OCPUs (smallest Half Rack increment), the monthly infrastructure charge doubles for each Oracle Exadata configuration increment (Quarter Rack to Half Rack, Half Rack to Full Rack).

Comparing Db2 Warehouse on Cloud (WoC) with Oracle Autonomous Data Warehouse (ADW)

Db2 WoC provides dedicated hardware compute resources — both cores and memory — to each Db2 WoC Flex or Flex Performance cluster. This will provide consistent database performance, in contrast to Oracle ADW-Shared. IBM gives you a dedicated database environment versus a dedicated PDB within a group of PDBs. Db2 WoC provides an INCLUDED data virtualization capability to allow both relational and non-relational (Hadoop) data sources from various vendors to be used “as-is” where the data currently resides in combination with the Oracle data that will be used for analytics processing in your new cloud data warehouse.

When compared to Oracle ADW-Dedicated, Db2 WoC Flex Performance provides a smaller initial configuration (48 cores vs. 96 cores) and more reasonable growth increments for both compute (24 core increments vs. 96 or 192 core increments) and storage (2.4 TB increments vs. 199 TB or 350 TB increments) while delivering excellent performance through the use of Db2 Massively Parallel Processing (MPP) architecture combined with BLU technology (dynamic in-memory column-organized tables). This combination of dedicated database resources, MPP architecture, and BLU technology within Db2 WoC Flex Performance provides the optimal data warehouse configuration for large data warehouses where query performance is critical.

Oracle Autonomous Data Warehouse (ADW) utilizes Oracle Exadata X8M-2 systems as its deployment platform and provides two configuration options — ADW-Shared and ADW-Dedicated. However, in contrast to the dedicated compute resources of Db2 WoC, Oracle ADW-Shared ONLY dedicates OCPUs (Oracle CPU which are equivalent to an Intel Xeon physical core [1]) and a single PDB (Pluggable Database) to each Oracle Cloud client in this configuration. The remainder of database resources within an Oracle Exadata system (database memory, Exadata Storage Server persistent memory, flash cache, and processor cores and memory) are shared among all PDBs within that Oracle Exadata machine. In order to receive dedicated memory, flash cache, and other resources on an Oracle Exadata system for their PDBs, a client must purchase Oracle ADW-Dedicated. For the Oracle ADW-Dedicated configurations, a client can choose from an Oracle Exadata Quarter Rack (96 cores maximum with 150 TB of storage), Half Rack (192 cores maximum with 349 TB of storage), or Full Rack system (384 cores maximum with 699 TB of storage) and this infrastructure will be dedicated to that client.

This multi-tenant configuration within Oracle ADW-Shared means that multiple client PDBs will coexist within a single Oracle Exadata configuration. Although Oracle can control data access and PDB separation from a security perspective, they do NOT dedicate memory and flash cache to specific PDBs (only OCPUs are dedicated). Even with Database Resource Manager to control database resources at the PDB level, an individual PDB CANNOT be guaranteed consistent performance between off-peak and peak usage periods of the Oracle Exadata appliance. For clients with strict SLAs for their production data warehouses, this type of data warehouse implementation (multi-tenant) will not be acceptable.  

Based on the descriptions of the two configurations, it would appear that Oracle is directing clients with production data warehouse or strict performance requirements to Oracle ADW-Dedicated. The drawback to Oracle ADW-Dedicated is that the infrastructure monthly cost is quite high (and this charge includes NO compute and query processing), starting at USD $10,800.00 per month for an Exadata X8M Quarter Rack system. The storage that is included with Oracle ADW-Dedicated is 150 TB of user capacity storage for a Quarter Rack, 349 TB of user capacity storage for a Half Rack, and 699 TB of user capacity storage for a Full Rack. These extremely large storage volumes make it difficult to justify an Oracle ADW-Dedicated environment for data warehouses with a data capacity of less than 100 TB. Clients with smaller data warehouse will either have to use Oracle ADW-Shared where they may encounter inconsistent performance in the multi-tenant environment or consolidate several data warehouses within an Oracle ADW-Dedicated environment.


IBM Db2 WoC provides dedicated compute resources regardless of the Db2 WoC configuration selected versus the multi-tenant, shared configuration of Oracle Autonomous Data Warehouse (ADW) Shared or the large initial size and large compute and storage increments of an Oracle ADW-Dedicated configuration with a minimum monthly dedicated infrastructure charge greater than USD $10,000.

Take the first step towards a more cost-effective cloud data warehouse platform by visiting the IBM Db2 Warehouse on Cloud website.

In part 2 of this blog, we will discuss the options available to Oracle clients and provide more details on why IBM Db2 Warehouse on Cloud is an excellent choice for performing analytics processing on Oracle transactional data along with a pricing example to provide a cost comparison of the two primary offerings (Db2 Warehouse on Cloud Flex Performance and Oracle Autonomous Data Warehouse Dedicated).

[1] Oracle CPU (OCPU) is defined by Oracle

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