Availability
True Cache
True Cache is an in-memory, consistent, and automatically managed cache for Oracle Database. It operates similarly to an Active Data Guard readers farm, except that True Cache is mostly diskless and is designed for performance and scalability, as opposed to disaster recovery. An application can connect to True Cache directly for read-only workloads. A general read-write Java application can also simply mark some sections of code as read-only, and the 23ai JDBC Thin driver can automatically send read-only workloads to configured True Caches.
Today, many Oracle users place a cache in front of the Oracle Database to speed up query response time and improve overall scalability. True Cache is a new way to have a cache in front of the Oracle Database. True Cache has many advantages including ease of use, consistent data, more recent data, and automatically managed cache.
Directory-Based Sharding Method
Directory-based sharding is a type of user-defined sharding in Oracle Globally Distributed Database where the location of data records associated with a sharding key is specified dynamically at the time of insert based on user preferences. The key location information is stored in a directory which can hold a large set of key values in the hundreds of thousands. With directory-based sharding, you have the freedom to move individual key values from one location to another, or make bulk movements to scale up or down, or for data and load balancing.
Directory-based sharding method improves the user-defined sharding model and provides linear scalability, complete fault isolation, and global data distribution for the most demanding applications.
Oracle Globally Distributed Database Raft Replication
Raft replication provides built-in replication for Oracle Globally Distributed Database without requiring configuration of Oracle GoldenGate or Oracle Data Guard. Raft replication is logical replication with consensus-based (RAFT) commit protocol, which enables declarative replication configuration and sub-second failover.
RAFT Replication helps simplify management, improves availability and SLA delivery, as well as optimizes hardware utilization for sharded database environments.
Automatic Data Move on Sharding Key Update
When you update the sharding key value on a particular row of a sharded table, the data with that key value might be mapped to a different partition or shard than where it currently resides. Oracle Globally Distributed Database now handles moving the data to the new location, whether it is in a different partition on the same shard or on a different shard.
This features makes data movement between partition or shards seamless when sharding key value update occurs due to various reasons, for example, a move to another country or change in roles.
Automatic Transaction Quarantine
System MONitor (SMON) is a background process responsible for transaction recovery. Transaction Quarantine can now automatically quarantine the recovery of problematic transactions while keeping the database open, allowing SMON to proceed with the recovery of the other transactions. Alerts and diagnostic information are provided to the DBA or operator so that they can review and resolve the quarantine while other database operations continue unaffected.
The benefit of transaction quarantining is increased fault tolerance and high availability of the database. The database stays up and running and continues processing transactions while the quarantine is being resolved.
Creating Immutable Backups Using RMAN
RMAN is now compatible with immutable OCI Object Storage using locked retention rules, which prevents deletion or modification of backups.
To help organizations meet ransomware protection or strict regulatory requirements for record management and retention, RMAN now prevents anyone, even an administrator, from deleting or modifying backups in OCI Object Storage.
Fine-Grained Refresh Rate Control For Duplicated Tables
Oracle Globally Distributed Database enables refresh rate control for individual duplicated tables. Each duplicated table can have a separate refresh rate which is defined either at its creation or by the ALTER TABLE statement.
This feature helps optimize the use of resources by customization of refresh rates for individual duplicated tables.
Global Partitioned Index Support on Subpartitions
Globally Distributed Database allows a global partitioned index on the sharding key when the sharded table is sub-partitioned. You can create a primary key/unique indexes on sharded tables that are composite partitioned without having to include sub-partition keys.
The benefit of this feature is that it removes the restriction on the primary key columns when the sharded table is sub-partitioned, as in the composite sharding method.
JDBC Support for Split Partition Set
This feature enables the Java connection pool (UCP) to receive ONS events about data in a chunk being split and moved across partition sets, and then update the sharding topology appropriately.
This feature furnishes high availability to Java applications using Sharded databases.
Managing Flashback Database Logs Outside the Fast Recovery Area
In previous releases, you could store flashback database logs only in the fast recovery area. Now you can optionally designate a separate location for flashback logging. For example, if you have write-intensive database workloads, then flashback database logging can slow down the database if the fast recovery area is not fast enough. In this scenario, you can now choose to write the flashback logs to faster disks. Using a separate destination also eliminates the manual administration to manage the free space in the fast recovery area.
Managing flashback database logs outside the fast recovery area lowers the operational costs related to space management and guarantees the best performance for workloads that are typically impacted by flashback logging on traditional storage.
New Duplicated Table Type - Synchronous Duplicated Table
Oracle Globally Distributed Database introduces a new kind of duplicated table that is synchronized on the shards 'on-commit' on the shard catalog. The rows in a duplicated table on the shards are synchronized with the rows in the duplicated table on the shard catalog when the active transaction performing DMLs on the duplicated tables in the shard catalog is committed.
This features enables efficient and absolute data consistency and synchronization for duplicated tables, across all shards at all times.
New Partition Set Operations for Composite Sharding
For Oracle Globally Distributed Database sharded databases using the composite sharding method, two new ALTER TABLE operations enhance partition set maintenance. Previously, partition set operations did not support specifying tablespace sets for child and reference-partitioned tables that are affected due to add and split partition set operations. MOVE PARTITIONSET lets you move a whole partition set from one tablespace set to another, within the same shardspace. MODIFY PARTITIONSET lets you add values to the list of values of a given partition set.
These new operations enhance resharding capability. MOVE PARTITIONSET gives you the control to move all subpartitions of a given table to another tablespace set, within a given shardspace. You can also specify separate tablespace sets for LOBs and subpartitions. MODIFY PARTITIONSET extends the add list values feature of partitions to partition sets.
Oracle Data Pump Adds Support for Sharding Metadata
Oracle Data Pump adds support for sharding DDL in the API dbms_metadata.get_ddl(). A new transform parameter, INCLUDE_SHARDING_CLAUSES, facilitates this support. If this parameter is set to true, and the underlying object contains it, then the get_ddl() API returns sharding DDL for create table, sequence, tablespace and tablespace set. To prevent sharding attributes from being set on import, the default value for INCLUDE_SHARDING_CLAUSES is set to false.
Oracle Data Pump supports sharding migration with support for sharding DDL. You can migrate sharding objects to a target database based on source database shard objects.
Oracle Globally Distributed Database Coordinated Backup and Restore Enhancements
Coordinated backup and restore functionality in Oracle Globally Distributed Database has been extended to include the following:
- Enhanced error handling and diagnosis for backup jobs
- Improved automation of sharded database restore
- Support for running RMAN commands from GDSCTL
- Support for using different RMAN recovery catalogs for different shards
- Encryption of backup sets
- Support for additional backup destinations: Amazon S3, Oracle Object Storage, and ZDLRA
The benefits of this functionality are:
- Easily diagnose problems in backup jobs
- Backups sets can be encrypted so that the data is secured
- Support for additional destinations other than on-disk storage
- Support for different RMAN catalogs and destinations to abide by data residency requirements
PL/SQL Function Cross-Shard Query Support
PL/SQL functions are enhanced with the keyword SHARD_ENABLE to allow these functions to be referenced in Oracle Globally Distributed Database cross-shard queries. With the new keyword, the query optimizer takes the initiative to push the execution of the PL/SQL function to the shards.
This feature significantly improves performance for PL/SQL functions in sharded database environments.
Parallel Cross-Shard DML Support
The Oracle Globally Distributed Database query coordinator runs cross-shard updates and inserts in parallel on multiple shards.
This feature improves cross-shard DML performance by running updates and inserts in parallel rather than serially.
Pre-Deployment Diagnostic for Oracle Globally Distributed Database
While processing GSDSCTL ADD SHARD, ADD GSM, and DEPLOY commands, Oracle Globally Distributed Database runs a series of checks to make sure that there is no potential environmental issue.
This feature proactively avoids common pitfalls to reduce time taken to complete a sharded database deployment.
Priority Transactions
If a transaction does not commit or roll back for a long time while holding row locks, it can potentially block other high-priority transactions. This feature allows applications to assign priorities to transactions and for administrators to set timeouts for each priority. The database will automatically roll back a lower priority transaction and release the row locks held if it blocks a higher priority transaction beyond the set timeout, allowing the higher priority transaction to proceed.
Priority Transactions reduces the administrative burden while also helping to maintain transaction latencies and SLAs on higher priority transactions.
RMAN Backup Encryption Algorithm Now Defaults to AES256
RMAN encrypted backups now default to AES256 encryption algorithm. RMAN will continue to support restore using existing backups created with AES128 or AES192 encryption algorithms. You may also choose to create new backups using AES128 by changing the default AES256 setting. This default change applies to BACKUP BACKUPSET command and the ALLOCATE CHANNEL command.
To strengthen the security of encrypted backups from being decrypted by malicious users, RMAN encrypted backups now default to the AES256 encryption standard.
RMAN Operational, Diagnostics, and Upgrade Enhancements
RMAN now includes easier standby database registration for Oracle Data Guard, better fault tolerance and optimization for Oracle Real Application Cluster (Oracle RAC), enhanced diagnosability which automatically gathers information to help identify issues, and updates to mitigate bottlenecks and pause sessions during recovery catalog upgrades.
RMAN operations are now easier and more resilient for highly available Oracle environments with less complex backup registration, automatic diagnostic gathering, and fewer failures when performing maintenance activities.
Simplified Database Migration Across Platforms Using RMAN
Using RMAN to migrate databases across different operating system platforms has been streamlined and includes support for databases encrypted with Transparent Data Encryption (TDE) and multi-section backups. New command options allow existing RMAN backups to be used to transport tablespaces or pluggable databases to a new destination database with minimal downtime.
Migrations using RMAN are now easier, faster, and require fewer steps to execute. The new capabilities enable a simple and straightforward migration process, minimizing downtime for your applications, reducing risk, and increasing productivity.
Support for Oracle Database Version Specific RMAN SBT Library
The Oracle Home directory now includes the database version compatible libraries (SBT_LIBRARY) for Zero Data Loss Recovery Appliance, OCI Object Storage and Amazon S3. You can now configure RMAN to directly access libraries from the Oracle Home directory using an alias. For example, if the backup destination is OCI Object Storage, you only have to specify the alias name oracle.oci for the SBT_LIBRARY parameter. When RMAN attempts to backup to Object Storage, it uses the specified alias to access the SBT library used for backup cloud service from the Oracle home directory.
The RMAN storage libraries are now included with the database, eliminating the need to download and install additional software and ensuring that you have all the necessary components to immediately start backing up and restoring from Zero Data Loss Recovery Appliance, OCI Object Storage, or Amazon S3.