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DB_LOAD(1) BerkeleyDB Utilities DB_LOAD(1)
NAME
db_load - Read and load data from standard input
SYNOPSIS
db_load [-nTV] [-c name=value] [-f input] [-h home] [-P password] [-t btree | hash | queue
| recno] file
db_load [-r lsn | fileid] [-h home] [-P password] file
DESCRIPTION
The db_load utility reads from the standard input and loads it into the database file. The
database file is created if it does not already exist.
The input to db_load must be in the output format specified by the db_dump utility, or as
specified by the -T option below.
OPTIONS
-c name=value
Specify configuration options ignoring any value they may have based on the input.
The command-line format is name=value. See the Supported Keywords section below
for a list of keywords supported by the -c option.
-f input
Read from the specified input file instead of from the standard input.
-h home
Specify a home directory for the database environment.
If a home directory is specified, the database environment is opened using the
DB_INIT_LOCK, DB_INIT_LOG, DB_INIT_MPOOL, DB_INIT_TXN, and DB_USE_ENVIRON flags to
DB_ENV->open. (This means that db_load can be used to load data into databases
while they are in use by other processes.) If the DB_ENV->open call fails, or if no
home directory is specified, the database is still updated, but the environment is
ignored; for example, no locking is done.
-n Do not overwrite existing keys in the database when loading into an already exist-
ing database. If a key/data pair cannot be loaded into the database for this rea-
son, a warning message is displayed on the standard error output, and the key/data
pair are skipped.
-P password
Specify an environment password. Although Berkeley DB utilities overwrite password
strings as soon as possible, be aware there may be a window of vulnerability on
systems where unprivileged users can see command-line arguments or where utilities
are not able to overwrite the memory containing the command-line arguments.
-r Reset the database's file ID or log sequence numbers (LSNs).
All database pages in transactional environments contain references to the environ-
ment's log records. In order to copy a database into a different database environ-
ment, database page references to the old environment's log records must be reset,
otherwise data corruption can occur when the database is modified in the new envi-
ronment. The -r lsn option resets a database's log sequence numbers.
All databases contain an ID string used to identify the database in the database
environment cache. If a database is copied, and used in the same environment as
another file with the same ID string, corruption can occur. The -r fileid option
resets a database's file ID to a new value.
In both cases, the physical file specified by the file argument is modified in-
place.
-T The -T option allows non-Berkeley DB applications to easily load text files into
databases.
If the database to be created is of type Btree or Hash, or the keyword keys is
specified as set, the input must 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 to be created is of type Queue or Recno and the keyword keys
is not set, the input must be lines of text, where each line is a new data item for
the database.
A simple escape mechanism, where newline and backslash (\) characters are special,
is applied to the text input. Newline characters are interpreted as record separa-
tors. Backslash characters in the text will be interpreted in one of two ways: If
the backslash character precedes another backslash character, the pair will be
interpreted as a literal backslash. If the backslash character precedes any other
character, the two characters following the backslash will be interpreted as a
hexadecimal specification of a single character; for example, \0a is a newline
character in the ASCII character set.
For this reason, any backslash or newline characters that naturally occur in the
text input must be escaped to avoid misinterpretation by db_load.
If the -T option is specified, the underlying access method type must be specified
using the -t option.
-t Specify the underlying access method. If no -t option is specified, the database
will be loaded into a database of the same type as was dumped; for example, a Hash
database will be created if a Hash database was dumped.
Btree and Hash databases may be converted from one to the other. Queue and Recno
databases may be converted from one to the other. If the -k option was specified
on the call to db_dump then Queue and Recno databases may be converted to Btree or
Hash, with the key being the integer record number.
-V Write the library version number to the standard output, and exit.
The db_load utility may be used with a Berkeley DB environment (as described for the -h
option, the environment variable DB_HOME, or because the utility was run in a directory
containing a Berkeley DB environment). In order to avoid environment corruption when
using a Berkeley DB environment, db_load should always be given the chance to detach from
the environment and exit gracefully. To cause db_load to release all environment
resources and exit cleanly, send it an interrupt signal (SIGINT).
EXIT STATUS
The db_load utility exits 0 on success, 1 if one or more key/data pairs were not loaded
into the database because the key already existed, and >1 if an error occurs.
ENVIRONMENT
DB_HOME
If the -h option is not specified and the environment variable DB_HOME is set, it
is used as the path of the database home, as described in DB_ENV->open.
EXAMPLES
The db_load utility can be used to load text files into databases. For example, the fol-
lowing command loads the standard UNIX /etc/passwd file into a database, with the login
name as the key item and the entire password entry as the data item:
awk -F: '{print $1; print $0}' < /etc/passwd |
sed 's/\\/\\\\/g' | db_load -T -t hash passwd.db
Note that backslash characters naturally occurring in the text are escaped to avoid inter-
pretation as escape characters by db_load.
SUPPORTED KEYWORDS
The following keywords are supported for the -c command-line ption to the db_load utility.
See DB->open for further discussion of these keywords and what values should be specified.
The parenthetical listing specifies how the value part of the name=value pair is inter-
preted. Items listed as (boolean) expect value to be 1 (set) or 0 (unset). Items listed
as (number) convert value to a number. Items listed as (string) use the string value
without modification.
bt_minkey (number)
The minimum number of keys per page.
chksum (boolean)
Enable page checksums.
database (string)
The database to load.
db_lorder (number)
The byte order for integers in the stored database metadata.
db_pagesize (number)
The size of database pages, in bytes.
duplicates (boolean)
The value of the DB_DUP flag.
dupsort (boolean)
The value of the DB_DUPSORT flag.
extentsize (number)
The size of database extents, in pages, for Queue databases configured to use
extents.
h_ffactor (number)
The density within the Hash database.
h_nelem (number)
The size of the Hash database.
keys (boolean)
Specify whether keys are present for Queue or Recno databases.
re_len (number)
Specify fixed-length records of the specified length.
re_pad (string)
Specify the fixed-length record pad character.
recnum (boolean)
The value of the DB_RECNUM flag.
renumber (boolean)
The value of the DB_RENUMBER flag.
subdatabase (string)
The subdatabase to load.
SEE ALSO
db_archive(1) db_checkpoint(1) db_deadlock(1) db_dump(1) db_hotbackup(1) db_log_verify(1)
db_printlog(1) db_recover(1) db_replicate(1) db_stat(1) db_tuner(1) db_upgrade(1) db_ver-
ify(1)
BerkeleyDB 5.3.21 06 December 2016 DB_LOAD(1)
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On Apache
Under GNU General Public License
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