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<title>Berkeley DB Reference Guide: Dump output formats</title>
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<td><dl><dt>Berkeley DB Reference Guide:<dd>Dumping and Reloading</dl></td>
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Dump output formats
There are two output formats used by <a href="../../utility/db_dump.html">db_dump</a> and <a href="../../utility/db_dump.html">db_dump185</a>.
In both output formats, the first few lines of the output contain header
information describing the underlying access method, filesystem page size,
and other bookkeeping information.
The header information starts with a single line, VERSION=N, where N is
the version number of the dump output format.
The header information is then output in name=value pairs, where name may
be any of the keywords listed in the <a href="../../utility/db_load.html">db_load</a> manual page, and
value will be its value. Although this header information can be manually
edited before the database is reloaded, there is rarely any reason to do
so because all of this information can also be specified or overridden by
command-line arguments to <a href="../../utility/db_load.html">db_load</a>.
The header information ends with single line HEADER=END.
Following the header information are the key/data pairs from the
database. If the database being dumped is a Btree or Hash database, or
if the -k option was specified, the output will be paired lines
of text where the first line of the pair is the key item, and the second
line of the pair is its corresponding data item. If the database being
dumped is a Queue or Recno database, and the -k option was not
specified, the output will be lines of text where each line is the next
data item for the database. Each of these lines is preceded by a single
space.
If the -p option to <a href="../../utility/db_dump.html">db_dump</a> or <a href="../../utility/db_dump.html">db_dump185</a> was
specified, the key/data lines will consist of single characters
representing any characters from the database that are printing
characters and backslash (\) escaped characters
for any that were not. Backslash characters appearing in the output mean
one of two things: if the backslash character precedes another backslash
character, it means that a literal backslash character occurred in the
key or data item. If the backslash character precedes any other
character, the next two characters must be interpreted as hexadecimal
specification of a single character; for example, \0a
is a newline character in the ASCII character set.
Although some care should be exercised, it is perfectly reasonable to use
standard text editors and tools to edit databases dumped using the
-p option before reloading them using the <a href="../../utility/db_load.html">db_load</a>
utility.
Note that the definition of a printing character may vary from system to
system, so database representations created using the -p
option may be less portable than those created without it.
If the -p option to <a href="../../utility/db_dump.html">db_dump</a> or <a href="../../utility/db_dump.html">db_dump185</a> is
not specified, each output line will consist of paired hexadecimal values;
for example, the line 726f6f74 is the string root in
the ASCII character set.
In all output formats, the key and data items are ended by a single line
DATA=END.
Where multiple databases have been dumped from a file, the overall output
will repeat; that is, a new set of headers and a new set of data items.
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