SDB (string 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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