DB_LOAD(1) BerkeleyDB Utilities DB_LOAD(1)
NAME
db_load - Read and load data from standard input
SYNOPSIS
db_load [-nTV] [-b blob-dir] [-c name=value] [-f input] [-h home] [-P
password] [-o blob-threshold] [-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 for the -T below.
OPTIONS
-b blob-dir
Identifies the directory where BLOB data is stored. If this
option is not specified, then BLOB data is placed in a subdirec-
tory within the DB's environment. See also the -o option.
-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 sup-
ported 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 existing database. If a key/data pair cannot be
loaded into the database for this reason, a warning message is
displayed on the standard error output, and the key/data pair
are skipped.
-o blob-threshold
Identifies the BLOB threshold in bytes. This threshold deter-
mines when a data item will be stored as a BLOB. Data items
sized less than this threshold are stored as normal data within
the database. Data items larger than this size are stored on-
disk in a subdirectory set aside for the purpose. Use the -b
command line option to identify where BLOB data is stored.
-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 argu-
ments.
-r Reset the database's file ID or log sequence numbers (LSNs).
All database pages in transactional environments contain refer-
ences to the environment's log records. In order to copy a
database into a different database environment, database page
references to the old environment's log records must be reset,
otherwise data corruption can occur when the database is modi-
fied in the new environment. The -r lsn option resets a data-
base'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 (\) char-
acters are special, is applied to the text input. Newline char-
acters are interpreted as record separators. Backslash charac-
ters 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 back-
slash 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 new-
line character in the ASCII character set.
For this reason, any backslash or newline characters that natu-
rally occur in the text input must be escaped to avoid misinter-
pretation 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 speci-
fied, 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 inter-
rupt 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 following 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 interpretation 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 key-
words and what values should be specified.
The parenthetical listing specifies how the value part of the
name=value pair is interpreted. 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 modi-
fication.
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 con-
figured 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_hot-
backup(1) db_log_verify(1) db_printlog(1) db_recover(1) db_replicate(1)
db_stat(1) db_tuner(1) db_upgrade(1) db_verify(1)
BerkeleyDB 5.3.28 06 December 2016 DB_LOAD(1)
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