radare2/shlr/sdb/README.md

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.

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Author
------
pancake <pancake@nopcode.org>

Contains
--------
* namespaces (multiple sdb paths)
* atomic database sync (never corrupted)
* bindings for vala, luvit, newlisp and nodejs
* command-line 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
* linked lists from r2 api

Compilation
-----------
For native builds just type `make`. Everything will be compiled twice to get the .dylib and .a and sdb in PIC and nonPIC modes.

To compile with Emscripten for Javascript:

	make CC=emcc EXT_EXE=.js

To crosscompile with meson:

```
$ cat > cross-file.txt <<EOF
[properties]
exe_wrapper = 'wine'
and then run meson build --cross-file cross-file.txt ; ninja -C build. It should work and it should create another binary called sdb_native.
EOF
$ meson build --cross-file cross-file.txt
$ ninja -C build
```

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
```

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 command-line 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
```