The LDB (Linked-list database) is a headless database management system focused in single-key, read-only application on vast amounts of data, while maintaining a minimal footprint and keeping system calls to a bare minimum. Information is structured using linked lists.
Building LDB requires openssl and zlib. Make sure packages zlib1g-dev and libssl-dev are installed.
Run make all to build the shell binary and the shared library.
Run make install to copy the binary to /usr/bin, the shared library to /usr/lib and the header to /usr/include.
Run ./run_test.sh to test the ldb binary.
Some of the features of the LDB are:
- Single, fixed size, numeric key (32-bit)
- Single-field records
- Larger keys also are supported by storing exceeded data keys in the data record.
- No indexing: Mapping
- Data tables define either fixed or variable-length data records
- Read-only
- Database updates are performed in a single-threaded, non-disruptive batch operation
- Zlib data compression
- Data records are organized in a linked list
- C library for native development
- LDB shell allows interaction with external languages
create database DBNAME
Creates an empty database
create table DBNAME/TABLENAME keylen N reclen N
Creates an empty table in the given database with
the specified key length (>= 4) and record length (0=variable)
show databases
Lists databases
show tables from DBNAME
Lists tables from given database
bulk insert DBNAME/TABLENAME from PATH with (CONFIG)
Imports data from PATH into the specified db/table. If PATH is a directory, its files will be recursively imported.
TABLENAME is optional and will be derived from the directory name's file if not specified.
(CONFIG) is a configuration string with the following format:
(FILE_DEL=1/0,KEYS=N,MZ=1/0,WFP=1/0,OVERWRITE=1/0,SORT=1/0,FIELDS=N,VALIDATE_FIELDS=1/0,VALIDATE_VERSION=1/0,VERBOSE=1/0,COLLATE=1/0,MAX_RECORD=N,TMP_PATH=/path/to/tmp)
Where 1/0 represents "true" / "false", and N is an integer.
FILE_DEL: Delete file after importation is completed.
KEYS: Number of binary keys in the CSV file.
MZ: MZ file indicator.
WFP: WFP file indicator.
OVERWRITE: Overwrite the destination table. (Default: 0).
SORT: Sort the tuples during the import process. (Default: 1).
FIELDS: Number of CSV fields.
VALIDATE_FIELDS: Check field quantity during importation. (Default: 1).
VALIDATE_VERSION: Validate version.json.(Default: 1).
VERBOSE: Enable verbose mode. (Default: 0).
THREADS: Define the number of threads to be used during the importation process. Defaul value: half of system available.
COLLATE: Perform collation after import, removing data larger than MAX_RECORD bytes. (Default: 0).
MAX_RECORD: Maximum record size in bytes (Default value: 2048).
MAX_RAM_PERCENT: limit the system RAM usage during collate process. Default value: 50.
TMP_PATH: Path to the folder used for temporary files (default: /tmp).
bulk insert DBNAME/TABLENAME from PATH
Imports data from PATH into the specified db/table. If PATH is a directory, its files will be recursively imported.
The configuration will be retrieved from the "db.conf" file located at "/etc/local/scanoss/ldb/". A default configuration file will be created if it doesn't exist.
insert into DBNAME/TABLENAME key KEY hex DATA
Inserts data (hex) into given db/table for the given hex key
insert into DBNAME/TABLENAME key KEY ascii DATA
Inserts data (ASCII) into db/table for the given hex key
select from DBNAME/TABLENAME key KEY
Retrieves all records from db/table for the given hex key (hexdump output)
select from DBNAME/TABLENAME key KEY ascii
Retrieves all records from db/table for the given hex key (ascii output)
select from DBNAME/TABLENAME key KEY csv hex N
Retrieves all records from db/table for the given hex key (csv output, with first N bytes in hex)
delete from DBNAME/TABLENAME max LENGTH keys KEY_LIST
Deletes all records for the given comma separated hex key list from the db/table. Max record length expected
collate DBNAME/TABLENAME max LENGTH
Collates all lists in a table, removing duplicates and records greater than LENGTH bytes
merge DBNAME/TABLENAME1 into DBNAME/TABLENAME2 max LENGTH
Merges tables erasing tablename1 when done. Tables must have the same configuration
unlink list from DBNAME/TABLENAME key KEY
Unlinks the given list (32-bit KEY) from the sector map
dump DBNAME/TABLENAME hex N
Dumps table contents with first N bytes in hex
dump keys from DBNAME/TABLENAME [sector N]
Dumps a unique list of existing keys
ldb -u [--update] path -n[--name] db_name -c[--collate]Create or update an existing database from "path." If "db_name" is not specified, "oss" will be used by default. If the "--collate" option is present, each table will be collated during the importation process.
ldb -f [filename]Process a list of commands from a file named "filename."q
The following example explains how to create a database, a table, a record, and querying that record.
$ echo "create database test" | ldb
OK
$ echo "create table test/table1 keylen 16 reclen variable" | ldb
OK
$ echo "insert into test/table1 key 26e3a3bd01585cde84408f01fe981f6a ascii THIS_IS_A_TEST" | ldb
$ echo "select from test/table1 key 26e3a3bd01585cde84408f01fe981f6a" | ldb
0000 544849535f49535f415f54455354 THIS_IS_A_TEST
$ echo "select from test/table1 key 26e3a3bd01585cde84408f01fe981f6a ascii" | ldb
THIS_IS_A_TEST
The LDB is released under the GPL 2.0 license. See the LICENSE file for more infomation.
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