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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：
LOG_ARCHIVE_FORMATis applicable only if you are using the redo log inARCHIVELOGmode. 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 theLOG_ARCHIVE_DESTparameter.
The following variables can be used in the format:
%slog sequence number
%Slog sequence number, zero filled
%tthread number
%Tthread number, zero filled
%aactivation ID
%ddatabase ID
%rresetlogs 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
theLOG_ARCHIVE_FORMATinitialization parameter is set in the parameter file, then make sure the parameter value contains the%s,%t, and%relements. Otherwise, the following error is displayed at the time
of instance startup:
ORA-19905: log_archive_format must contain %s, %t and %r
NeitherLOG_ARCHIVE_DESTnorLOG_ARCHIVE_FORMAThave to be complete file or directory specifiers themselves; they only need to form a valid file path after the variables are substituted intoLOG_ARCHIVE_FORMATand
the two parameters are concatenated together.
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