U:RDoc::NormalClass[iI"DBM:ET@I"Object;To:RDoc::Markup::Document:@parts[o;;[S:RDoc::Markup::Heading:
leveli:	textI"Introduction;To:RDoc::Markup::BlankLineo:RDoc::Markup::Paragraph;[I"6The DBM class provides a wrapper to a Unix-style ;TI"I{dbm}[http://en.wikipedia.org/wiki/Dbm] or Database Manager library.;T@o;
;[I"LDbm databases do not have tables or columns; they are simple key-value ;TI"Odata stores, like a Ruby Hash except not resident in RAM. Keys and values ;TI"must be strings.;T@o;
;[I"NThe exact library used depends on how Ruby was compiled. It could be any ;TI"of the following:;T@o:RDoc::Markup::List:
@type:BULLET:@items[
o:RDoc::Markup::ListItem:@label0;[o;
;[I"6The original ndbm library is released in 4.3BSD. ;TI"KIt is based on dbm library in Unix Version 7 but has different API to ;TI"-support multiple databases in a process.;To;;0;[o;
;[I"F{Berkeley DB}[http://en.wikipedia.org/wiki/Berkeley_DB] versions ;TI"G1 thru 5, also known as BDB and Sleepycat DB, now owned by Oracle ;TI"Corporation.;To;;0;[o;
;[I"PBerkeley DB 1.x, still found in 4.4BSD derivatives (FreeBSD, OpenBSD, etc).;To;;0;[o;
;[I"N{gdbm}[http://www.gnu.org/software/gdbm/], the GNU implementation of dbm.;To;;0;[o;
;[I"E{qdbm}[http://fallabs.com/qdbm/index.html], another open source ;TI"reimplementation of dbm.;T@o;
;[I"EAll of these dbm implementations have their own Ruby interfaces ;TI"8available, which provide richer (but varying) APIs.;T@S;	;
i;I"
Cautions;T@o;
;[I"MBefore you decide to use DBM, there are some issues you should consider:;T@o;;;;[	o;;0;[o;
;[I"HEach implementation of dbm has its own file format. Generally, dbm ;TI"Flibraries will not read each other's files. This makes dbm files ;TI"$a bad choice for data exchange.;T@o;;0;[o;
;[I"LEven running the same OS and the same dbm implementation, the database ;TI"Lfile format may depend on the CPU architecture. For example, files may ;TI"Mnot be portable between PowerPC and 386, or between 32 and 64 bit Linux.;T@o;;0;[o;
;[I"ODifferent versions of Berkeley DB use different file formats. A change to ;TI"=the OS may therefore break DBM access to existing files.;T@o;;0;[o;
;[
I"MData size limits vary between implementations. Original Berkeley DB was ;TI"Jlimited to 2GB of data. Dbm libraries also sometimes limit the total ;TI"Lsize of a key/value pair, and the total size of all the keys that hash ;TI"Oto the same value. These limits can be as little as 512 bytes. That said, ;TI"Ggdbm and recent versions of Berkeley DB do away with these limits.;T@o;
;[I"QGiven the above cautions, DBM is not a good choice for long term storage of ;TI"Mimportant data. It is probably best used as a fast and easy alternative ;TI"4to a Hash for processing large amounts of data.;T@S;	;
i;I"Example;T@o:RDoc::Markup::Verbatim;[I"require 'dbm'
;TI".db = DBM.open('rfcs', 666, DBM::WRCREAT)
;TI"Jdb['822'] = 'Standard for the Format of ARPA Internet Text Messages'
;TI"Ndb['1123'] = 'Requirements for Internet Hosts - Application and Support'
;TI"=db['3068'] = 'An Anycast Prefix for 6to4 Relay Routers'
;TI"puts db['822'];T:@format0:
@fileI"ext/dbm/dbm.c;T:0@omit_headings_from_table_of_contents_below0;0;0[[
U:RDoc::Constant[iI"READER;TI"DBM::READER;T00o;;[o;
;[I"IIndicates that dbm_open() should open the database in read-only mode;T@;@t;0@t@cRDoc::NormalClass0U;[iI"WRITER;TI"DBM::WRITER;T00o;;[o;
;[I"JIndicates that dbm_open() should open the database in read/write mode;T@;@t;0@t@@
{0U;[iI"WRCREAT;TI"DBM::WRCREAT;T00o;;[o;
;[I"LIndicates that dbm_open() should open the database in read/write mode, ;TI"/and create it if it does not already exist;T;@t;0@t@@
{0U;[iI"
NEWDB;TI"DBM::NEWDB;T00o;;[o;
;[I"LIndicates that dbm_open() should open the database in read/write mode, ;TI"Kcreate it if it does not already exist, and delete all contents if it ;TI"does already exist.;T;@t;0@t@@
{0U;[iI"VERSION;TI"DBM::VERSION;T00o;;[
o;
;[I"%Identifies ndbm library version.;T@o;
;[I"Examples:;T@o;;;;[
o;;0;[o;
;[I""ndbm (4.3BSD)";To;;0;[o;
;[I"+"Berkeley DB 4.8.30: (April  9, 2010)";To;;0;[o;
;[I","Berkeley DB (unknown)" (4.4BSD, maybe);To;;0;[o;
;[I"B"GDBM version 1.8.3. 10/15/2002 (built Jul  1 2011 12:32:45)";To;;0;[o;
;[I""QDBM 1.8.78";T;@t;0@t@@
{0[[I"Enumerable;To;;[;@t;0I"ext/dbm/dbm.c;T[[I"
class;T[[:public[[I"new;T@
Æ[I"	open;T@
Æ[:protected[[:private[[I"
instance;T[[;[([I"[];T@
Æ[I"[]=;T@
Æ[I"
clear;T@
Æ[I"
close;T@
Æ[I"closed?;T@
Æ[I"delete;T@
Æ[I"delete_if;T@
Æ[I"	each;T@
Æ[I"
each_key;T@
Æ[I"each_pair;T@
Æ[I"each_value;T@
Æ[I"empty?;T@
Æ[I"
fetch;T@
Æ[I"
has_key?;T@
Æ[I"has_value?;T@
Æ[I"
include?;T@
Æ[I"invert;T@
Æ[I"key;T@
Æ[I"	key?;T@
Æ[I"	keys;T@
Æ[I"length;T@
Æ[I"member?;T@
Æ[I"reject;T@
Æ[I"reject!;T@
Æ[I"replace;T@
Æ[I"select;T@
Æ[I"
shift;T@
Æ[I"	size;T@
Æ[I"
store;T@
Æ[I"	to_a;T@
Æ[I"to_hash;T@
Æ[I"update;T@
Æ[I"value?;T@
Æ[I"values;T@
Æ[I"values_at;T@
Æ[;[[;[[[U:RDoc::Context::Section[i0o;;[;0;0[@t@tcRDoc::TopLevel