jlogdup
The jlogdup command provides the capability to duplicate log set data from
the jBASE Transaction Journal. This command can be used to duplicate log data to
or from any platform file, including device files, standard input, ‘stdin’, and
standard output, ‘stdout’.
SYNTAX
jlogdup -Options INPUT input_spec OUTPUT output_spec
SYNTAX ELEMENTS
Options
| Option |
Description |
| -e file |
error file for database update errors |
| -f |
used with the -v or -V option; shows information for the next (future)
update; by default information for past updates is displayed |
| -h |
display help |
| -l file |
log file to write all status and errors information |
| -m nn |
maximum number of errors (default 10000) |
| -u nn |
display '*' every nn input records |
| -v |
verbose mode, 1 line per record |
| -x |
exclusive use of the database, no group locks taken |
| -H |
display verbose help screen |
| -V |
very verbose output, also 1 line per record |
input_spec/output_spec
The input/output specification can specify one or more of the following
parameters
| Parameter |
Description |
| blockmax=nnn (S) |
the maximum size, in blocks, of a serial device |
| blocksize=nnn |
the block size to read/write to TTY/SERIAL device or file |
| device=file%dev (S) |
the file name for SERIAL device. Can be more than one |
| end=timespec (I) |
time in log set at which to stop restore/duplication |
| noflush=true (O) |
suppress flush of output at end of transaction. (default false) |
| notrans=true (O) |
ignore transaction boundaries. (default false) |
| prompt=true |
prompt when switching serial devices or files |
| rename=from,to |
convert path name directories ‘from’ to ‘to’ on restore |
| renamefile=file (O) |
use rename file list of format ‘from,to’ to rename files |
| retry=nn (I) |
specifies the interval between retries, when 'terminate=wait' |
| set=current (IL) |
begin restore/duplication using the current log set as input |
| set=database (OD) |
output is to the database, i.e. Restore mode |
| set=eldest (IL) |
begin restore/duplication using the eldest log set |
| set=n (ILN) |
begin restore/duplication using log set number n |
| set=null (O) |
output is to be discarded |
| set=serial (S) |
input/output is to a serial device or file. Requires ‘device=’ |
| set=stdin (IT) |
the input data comes from the terminal stdin |
| set=stdout (OT) |
the output data is directed to the terminal stdout |
| set=tty (T) |
the input is from stdin or the output is to stdout |
| set=logset (OL) |
the output is directed to the current log set as an update |
| start=timespec (I) |
time in log set at which to start restore/duplication |
| terminate=eof (I) |
terminate restore/duplication at eof of eldest log set |
| terminate=eos (I) |
terminate restore/duplication at end of current log set |
| terminate=wait (I) |
switch to elder log sets as required and wait for new updates |
| timeout=nnn (I) |
timeout period in seconds for ‘terminate=wait' |
| verbose=true |
display to stderr a summary of the specification |
The indicators in brackets denote:
| Indicator |
Meaning |
| D |
specification valid for type database |
| I |
specification valid for type input |
| O |
specification valid for type output |
| L |
specification valid for log set |
| N |
specification valid for type of null |
| S |
specification valid for type serial |
| T |
specification valid for type terminal |
timespec
The time specification, used in the ‘start=’ and ‘end=’ specification can be
one of the following formats:
| timespec |
meaning |
| hh:mm:ss |
time of day (todays date assumed) |
| DD-MMM-YYYY |
date (midnight assumed), Any date convention accepted |
| hh:mm:ss,DD-MM-YYYY |
both time and date specified either way around |
| jbackup_file |
time of file created. Use with 'jbackup -sfilename' option |
| filename |
regular file, use the time the file was last modified |
LOGFILE
The transaction journal log can be accessed via a special file. The
CREATE-FILE command can be used to create the file stub:
CREATE-FILE TJ1 TYPE=TJLOG
[ 417 ] File TJ1]D created , type = J4
[ 417 ] File TJ1 created , type = TJLOG
This creates an entry in the current directory:
TJ1
JBC__SOB jBASE_TJ_INIT SET: set=current terminate=eos
When a file of type TJLOG is
created a set of dictionary records are
generated in the dictionary section of the TJLOG file, which is a normal j4 hash
file. The data section of a TJLOG file is handled by a special JEDI driver,
which accesses the current log set. The log set can be changed by additional
parameters when creating the TJLOG file after the TYPE specification. e.g.
CREATE-FILE TJ2 TYPE=TJLOG set=eldest
The following record types are used in the transaction journal log (see
dictionary item TYPE).
| Type |
Description |
| EOF |
end of file |
| WRITE |
record Written |
| DELETE |
record Deleted |
| CLEARFILE |
file Cleared |
| DELETEFILE |
file Deleted |
| CREATEFILE |
file Created |
| TRANSTART |
transaction Started |
| TRANSEND |
transaction Committed |
| TRANSABORT |
transaction Aborted |
The jlogdup command enables selective restores to be performed by preceding
the jlogdup command with a select list. The select list can be generated from
the log set by generating a special file
type, which uses the current log set as the data file.
EXAMPLE
:CREATE-FILE TJFILE TYPE=TJLOG
[ 417 ] File TJFILE]D created , type = J4
[ 417 ] File TJFILE created , type = TJLOG
:SSELECT TJFILE WITH PATH EQ "/home/jdata/CUSTOMER" AND WITH TYPE NE
"CLEARFILE"
167 Records selected
>jlogdup INPUT set=current OUTPUT set=database
In this example, all updates to the CUSTOMER file which have been logged,
except for any CLEARFILEs, are re-applied to the CUSTOMER file.
Transaction Journaling
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