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SDB (simple database)

sdb is a simple string key/value database based on djb's cdb disk storage and supports JSON and arrays introspection.

mcsdbd is a memcache server with disk storage based on sdb. It is distributed as a standalone binary and a library.

There's also the sdbtypes: a vala library that implements several data structures on top of an sdb or a memcache instance.

Author

pancake pancake@nopcode.org

Contains

  • namespaces (multiple sdb paths)
  • atomic database sync (never corrupted)
  • bindings for vala, luvit, newlisp and nodejs
  • commandline frontend for sdb databases
  • memcache client and server with sdb backend
  • arrays support (syntax sugar)
  • json parser/getter (js0n.c)

Rips

  • disk storage based on cdb code
  • memory hashtable based on wayland code
  • linked lists from r2 api

Changes

I have modified cdb code a little to create smaller databases and be memory leak free in order to use it from a library.

The sdb's cdb database format is 10% smaller than the original one. This is because keylen and valuelen are encoded in 4 bytes: 1 for the key length and 3 for the value length.

In a test case, a 4.3MB cdb database takes only 3.9MB after this file format change.

Usage example

Let's create a database!

$ sdb d hello=world
$ sdb d hello
world

Using arrays (>=0.6):

$ sdb - '()list=1,2' '(0)list' '(0)list=foo' '()list' '(+1)list=bar'
1
foo
2
foo
fuck
2

Let's play with json:

$ sdb d g='{"foo":1,"bar":{"cow":3}}'
$ sdb d g?bar.cow
3
$ sdb - user='{"id":123}' user?id=99 user?id
99

Using the commandline without any disk database:

$ sdb - foo=bar foo a=3 +a -a
bar
4
3

$ sdb -
foo=bar
foo
bar
a=3
+a
4
-a
3

Remove the database

$ rm -f d

Backups

To make a backup of a database to move it between different boxes use the textual format:

$ sdb my.db | xz > my.xz
$ du -hs my.*
my.db        3.9M
my.xz        5K

Using ascii+xz is the best option for storing compressed sdb databases:

$ gzip < my.db | wc -c
  110768
$ xz -9 < my.db | wc -c
  37480
$ sdb my.db | xz -9 | wc -c
  5620
$ sdb my.db | lzma -9 | wc -c
  5575

To import the database:

$ xz -d < my.xz | sdb my.db =
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