Data Guard broker 19c edit database set parameter feature is unstable

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By Brian Fitzgerald

Introduction

New in Oracle Database 19c, you can set a database initialization parameter directly from dgmgrl, the Data Guard broker command-line interface. The documentation is not clear or the feature is unstable.

Edit database set parameter

The basic functionality works as documented.

DGMGRL> edit database PRIM set parameter pga_aggregate_target='752m';
Parameter "pga_aggregate_target" updated

However:

DGMGRL> edit database PRIM set parameter pga_aggregate_target='753m' sid='PRIM';
edit database PRIM set parameter pga_aggregate_target='753m' sid='PRIM';
                                                                ^
Syntax error before or at "="

DGMGRL> edit database PRIM set parameter sga_target=2256m scope = both;
edit database PRIM set parameter sga_target=2256m scope = both;
                                                        ^
Syntax error before or at "="

Options SID and SCOPE are documented but are not working for me.

Edit database reset parameter

You can use edit database to reset a database initialization parameter. Suppose spfile initially contains:

*.use_large_pages='ONLY'
PRIM.use_large_pages='ONLY'

Now reset.

DGMGRL> edit database PRIM reset parameter use_large_pages;
ORA-16675: database instance restart required for property value modification to take effect

Parameter "use_large_pages" reset
DGMGRL>

This appears in the alert log

2019-10-17T19:43:49.034727+00:00
ALTER SYSTEM RESET use_large_pages SCOPE=SPFILE;

Here is what is remains:

PRIM.use_large_pages='ONLY'

The “sid=’*'” entry is gone. The dgmgrl reset behavior, then, is the same as the alter system syntax with an assumed “sid=’*'”.

The dgmgrl edit database reset parameter command has no sid option.

DGMGRL> edit database PRIM reset parameter use_large_pages sid = 'PRIM';
edit database PRIM reset parameter use_large_pages sid = 'PRIM';
                                                   ^
Syntax error before or at "sid"

Conclusion

The dgmgrl edit database set and reset parameter commands are incomplete or have unexpected behavior today, or I misunderstand them. I will not use them for now.

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