Oracle DBA

In Oracle 19c, enhancements in the Data Guard Broker enable DBAs to set, reset, and display database initialization parameters directly through the broker interface. These commands allow parameter changes to take effect immediately on the active database (or standby, or Far Sync) without first editing the broker configuration file.

This article explains these new commands, when to use them, and shows examples of usage and output.

Why This Matters

Traditionally, changes to initialization parameters in a Data Guard setup often involved:

• Logging into the target or standby database directly
• Editing SPFILE or parameter files
• Restarting or bouncing instances
• Ensuring consistency across broker configuration

With the new Broker commands in 19c, you can perform many of these tasks centrally via DGMGRL, simplifying management and reducing human error.

Supported Commands in Broker (19c+)

1. EDIT DATABASE
2. EDIT DATABASE RESET
3. SET TRACE_LEVEL

These commands apply parameter changes directly to the database, not stored in the broker’s configuration file. They support scopes like SPFILE, MEMORY, or BOTH. By default, the scope is BOTH.

• For static parameters, you must use SCOPE = SPFILE.
• You may specify a particular instance via SID; else use SID = '*' to apply across all instances.

Command Syntax & Examples

1. EDIT DATABASE … SET PARAMETER

Use this to change the value of an initialization parameter:

DGMGRL> EDIT DATABASE 'chennai' SET PARAMETER log_archive_trace = 1 SCOPE = BOTH;
Parameter "log_archive_trace" updated

This command updates the parameter log_archive_trace on the database named chennai.

2. EDIT DATABASE … RESET PARAMETER

This returns a parameter to its default or previous setting:

DGMGRL> EDIT DATABASE 'chennai' RESET PARAMETER log_archive_trace;
Parameter "log_archive_trace" reset

3. SET TRACE_LEVEL

This controls the broker tracing verbosity. (In versions prior to 19c, DEBUG was used. In 19c+, it’s TRACE_LEVEL.)

DGMGRL> SET TRACE_LEVEL SUPPORT;
DGMGRL> SHOW ALL
trace_level         SUPPORT
echo                OFF
time                OFF
observerconfigfile  = observer.ora

Default trace level is USER, which records standard operational events. Setting it to SUPPORT will increase the trace details, useful when troubleshooting or working with Oracle Support.

New Mapping of Broker Properties to Database Parameters

Another powerful change: many Data Guard Broker properties are now directly mapped to the underlying database parameters. Examples include:

• ArchiveLagTarget
• DataGuardSyncLatency
• LogArchiveMaxProcesses
• LogArchiveMinSucceedDest
• LogArchiveTrace
• StandbyFileManagement
• DbFileNameConvert
• LogArchiveFormat
• LogFileNameConvert

Thus, when you use EDIT DATABASE SET PARAMETER ..., you’re effectively updating these Broker properties at the database level.

Rules, Limitations & Considerations

• The target database must be OPEN and running when executing these commands.
• You cannot connect to a remote database with OS authentication for these changes.
• For static parameters, use SCOPE = SPFILE (you may need to bounce the instance for changes to take effect).
• In RAC environments, changes affect all instances by default.

Summary & Best Practices

• Use EDIT DATABASE SET PARAMETER and EDIT DATABASE RESET PARAMETER in DGMGRL to streamline parameter changes in Data Guard setups.
• Use SET TRACE_LEVEL instead of the old DEBUG keyword in 19c+.
• Always validate parameter changes and ensure your scope is correct (MEMORY, SPFILE, or BOTH).
• For production systems, test changes in a controlled environment before applying.