Oracle 18c: New Features for Oracle Data Guard
New Broker VALIDATE commands
Personally, at the time to check or correct Oracle Data Guard configurations, one of the most common problems is the network configuration. Sometimes we are building RAC-RAC configurations with many servers.. many IPs.. etc.. and it’s natural we can miss a name.. and IP.. etc.. at the end we can have some problems when this configuration is working and we have to start the tedious job to check every single detail.. ( Network Configuration.. Parameters.. etc.. ) to find where it’s the problem.. With these 3 following commands we will be able to save a lot of time when we face that kind of difficulties..
VALIDATE DATABASE SPFILE
- Validate parameters settings between the Primary and a Standby database.
VALIDATE NETWORK CONFIGURATION
- Validate the network setup between all databases in the configuration
VALIDATE STATIC CONNECT IDENTIFIER
- Verifies the static connect identifier setup in Single Instance databases the do not have Oracle Restart.
Multi-Instance Redo Apply
– Multi-Instance Redo Apply allows all standby nodes to participate in recovery
– In-memory DB (IMC) on Active Data Guard allows:
- Creation of IMC tables and columns for analytics on Active Data Guard
- Population with different data than production database
- Offloading even more to your standby!
– IMC now works with Multi-Instance Redo Apply!
– Multi-Instance Redo apply also works with BCT
* Available only on Exadata and Oracle Cloud Offerings
18c: RMAN and Data Guard Enhancements
Active Data Guard Sync
- New RECOVER STANDBY DATABASE FROM SERVICE
- One command to refresh the standby database
- Refreshes controlfile, datafile, restores newly added datafiles
- Start RMAN and connect as target to the physical standby database.
- Roll forward the physical standby database using the RECOVER STANDBY DATABASE command with the FROM SERVICE clause
RECOVER STANDBY DATABASE FROM SERVICE primary_db;
Creating GTTs on Active Data Guard
– Creating GTTs today will fail when executed on Active Data Guard
– In Oracle Database 18c CREATE GLOBAL TEMPORARY TABLE on an Active Data Guard standby will:
- Create the GTT on the Primary
- Wait for the GTT to be replicated and applied to the Active Data Guard standby
- Return control to the user
Transient tables useful for reporting applications
Global temporary tables
Persistent, shared (global) table definition
Temporary, private (session-based) data content
- Data physically exists for a transaction or session
- Session-private statistics
Private temporary tables (18c)Temporary, private (session-based) table definition
- Private table name and shape
Temporary, private (session-based) data content
- Session or transaction duration
Executing DML on Active Data Guard
– DML Re-direction automatically performed from Active Data Guard standby to the Primary without compromising ACID
- Standby ADG session waits for updates to show up on ADG via redo apply
- DML data re-directed by an ADG session is only visible to that session before commit
- DML data re-directed is visible to all sessions after ADG session commits
- Enabled by setting parameter _enable_proxy_adg_redirect=TRUE and appropriate connectivity parameters
- Respects ACID properties of a database for ADG session
- Targeted for “Read Mostly Occasional Updates” applications
Keep Buffer Cache at Role Change
How often we did not dream for having a switchover without losing some transactions because of that..
Well, part of that dream “come true”..
– The database buffer cache state will be maintained on an ADG standby during a role change
– Automatic, nothing to set up.
- Services need to be configured correctly
Control login attempts
– The ADG_ACCOUNT_INFO_TRACKING parameter extends the control of user account security information and reaction.
- ‘LOCAL’ (default value) continues to enforce the existing behavior
- Maintains local copy of users account information in the Standby’s in-memory view.
- Login failures are only tracked locally on a per database basis and login denied when the failure maximum is reached.
– ‘GLOBAL’ triggers the new secure behavior
- Maintains a single global copy of users account info across all Data Guard databases
- Login failures across all databases in the Data Guard configuration count towards the maximum count and logins anywhere will be denied when the count is reached.
Data Guard and No Force Logging
How often you have been in the situation to repair/reinstate an Standby Database because a load was done in “No Logging mode”.
It was really a hard situation for many companies to know that some specific loads could be done very efficient and fast in “No Logging mode” but sometimes there was not another option if we wanted to preserve the health state of our standby databases. Now, we have a new feature to make more versatile some specific loads in “No Logging mode”
- Extended to provide better support in an Active Data Guard environment without significantly increasing the amount of redo generated.
- Two new modes are added as alternatives to the existing nologging mode
- Standby Nologging for Load Performance
- Ensures that standbys will receive the nonlogged data changes with the minimum impact to the speed of loading at the primary
- The standby can transiently have nonlogged blocks. These nonlogged blocks will be automatically resolved by managed standby recovery.
- Standby Nologging for Data availability
- Ensures all standbys have the data when the primary load commits but at the cost of throttling the speed of loading data at the primary
- The standbys will never have any nonlogged blocks.
In Oracle Release 12.1 & 12.2 there a lot of new features that perhaps you have not experimented up to now. Here we have a list of all them so that you can differentiate to what release belongs the new features you will use.
RMAN
Review – Data Guard 12.1 New Features Summary
Data Guard
- SYSDG Role for Data Guard specific operations
- Multitenant Database Standbys
- Default Real Time Apply
- Transparent Online Data file movement
- Single SQL*Plus Switchover command
- No Primary instance shutdown for switchover
- FastSync (SYNC NOAFFIRM)
- Enhanced Extended Datatype Support for upgrades
- Logical Standby support for additional data types
- XMLType data for all storage models, Oracle Spatial, Oracle Multimedia, Oracle Text, Objects and Collections (including VARRAYs and nested collections), Database File System (DBFS), XDB, Oracle SecureFiles (deduplication), and User-defined types.
- DBMS_SCHEDULER support for Rolling Upgrades
- Broker VALIDATE DATABASE capability
- Enhanced Broker configuring with RedoRoutes
- Broker Resumable switchover
- New Broker Observer properties and capabilities
- Broker support of Cascading Redo destinations
Active Data Guard
- Real Time Cascading Redo destinations
- WAN Distance Zero Data Loss with Far Sync
- Global Temporary Table DML on a standby
- Sequences (global and session) on a standby
- DBMS_ROLLING automated rolling upgrades
- Support for Oracle Application Continuity
- Support for Oracle Global Data Services
Review – Data Guard 12.2 New Features Summary
Data Guard
- Use DBCA and EMCLI to create Standbys
- Use RMAN and Enterprise Manager to create Far Sync Instances in addition to Standbys
- Rest Interface to the Data Guard Broker
- Chef tools to create and manage Data Guard standbys
- Scripting with the Broker DGMGRL command line interface
- Easily creating Subset Standby databases in Multitenant
- Migrate and Failover PDBs with the Broker
- Automatic Password File management
- Easy repair of No Logging operations
- Data File Block Comparison between Primary and Standby
- Multiple FSFO Targets and Observers
- FSFO in Maximum Protection mode
- Zero Data Loss Failovers in any mode with Storage Failures
- Enhanced control of Alternate destinations
- Convert to TDE easily with little or no downtime
Active Data Guard
- Using all your Standby Instances to apply redo
- Data Guard Broker Support and involvement in DBMS_ROLLING controlled rolling upgrades
- Use the In Memory Column Store on your Standby
- Use AWR and SQL Tuning Advisor to diagnose and tune Redo Apply and Query issues on your Active Data Guard Standby
- Move users transparently during role change with Session Draining on the Primary and Preserving existing connections at the Active Data Guard Standby
- More protection with Auto Block repair enhancements
this is the end of this article