OCP-1Z0-053-V12.02-64题

64.You performed an incomplete recovery and opened the database with the RESETLOGS option. The
LOG_ARCHIVE_FORMAT parameter is set to 'ora_%t_%s_%r.log'. Which statement regarding the
archived redo log files, created in an earlier incarnation of the database, is true?
A. The archived redo log files will be overwritten.
B. The archived redo log files are deleted automatically.
C. The archived redo log files should be moved to some other location.
D. The archived redo log files are still maintained because the file names are unique.
Answer: D
答案解析：
参考：http://docs.oracle.com/cd/E11882_01/server.112/e40402/initparams128.htm#REFRN10089

LOG_ARCHIVE_FORMAT

is applicable only if you are using the redo log in

ARCHIVELOG

mode. Use a text string and variables to specify the default filename format when archiving redo log files. The string
generated from this format is appended to the string specified in the

LOG_ARCHIVE_DEST

parameter.
The following variables can be used in the format:

%s

log sequence number

%S

log sequence number, zero filled

%t

thread number

%T

thread number, zero filled

%a

activation ID

%d

database ID

%r

resetlogs ID that ensures unique names are constructed for the archived log files across multiple incarnations of the database

Using uppercase letters for the variables (for example,

%S

) causes the value to be fixed length and padded to the left with zeros. An example of specifying the archive redo log filename format follows:
LOG_ARCHIVE_FORMAT = 'log%t_%s_%r.arc'
Archive log file names must contain each of the elements

%s

(sequence),

%t

(thread), and

%r

(resetlogs ID) to ensure that all archive log file names are unique. If
the

LOG_ARCHIVE_FORMAT

initialization parameter is set in the parameter file, then make sure the parameter value contains the

%s

,

%t

, and

%r

elements. Otherwise, the following error is displayed at the time
of instance startup:

ORA-19905: log_archive_format must contain %s, %t and %r
Neither

LOG_ARCHIVE_DEST

nor

LOG_ARCHIVE_FORMAT

have to be complete file or directory specifiers themselves; they only need to form a valid file path after the variables are substituted into

LOG_ARCHIVE_FORMAT

and
the two parameters are concatenated together.