Acces Methods

These are the common methods for BDB1::Btree, BDB1::Hash,

• Class Methods
• Methods

Class Methods

type[hash]

type[bdb1]

create a new temporary db file, populated with the given object

create([name, flags, mode, options])

new([name, flags, mode, options])

open([name, flags, mode, options])

open the database

name

The argument name is used as the name of a single physical file on disk that will be used to back the database.

flags

The flags must be the string "r", "r+", "w", "w+", "a", "a+" or and integer value.

The flags value must be set to 0 or by bitwise inclusively OR'ing together one or more of the following values

BDB1::CREATE

Create any underlying files, as necessary. If the files do not already exist and the DB_CREATE flag is not specified, the call will fail.

BDB1::EXCL

Return an error if the database already exists. Underlying filesystem primitives are used to implement this flag. For this reason it is only applicable to the physical database file and cannot be used to test if a subdatabase already exists.

BDB1::NOMMAP

Do not map this database into process memory.

BDB1::RDONLY

Open the database for reading only. Any attempt to modify items in the database will fail regardless of the actual permissions of any underlying files.

BDB1::TRUNCATE

Physically truncate the underlying database file, discarding all previous subdatabases or databases. Underlying filesystem primitives are used to implement this flag. For this reason it is only applicable to the physical database file and cannot be used to discard subdatabases.

The DB_TRUNCATE flag cannot be transaction protected, and it is an error to specify it in a transaction protected environment.

BDB1::WRITE

Open the database for writing. Without this flag, any attempt to modify items in the database will fail.

options for all classes

Hash, Possible options are

set_flags

general database configuration

set_cachesize

set the database cache size

set_pagesize

set the underlying database page size

set_lorder

set the database byte order

set_store_key

specify a Proc called before a key is stored

set_fetch_key

specify a Proc called after a key is read

set_store_value

specify a Proc called before a value is stored

set_fetch_value

specify a Proc called after a value is read

options specific to BDB1::Btree

set_bt_compare

specify a Btree comparison function

set_bt_minkey

set the minimum number of keys per Btree page

set_bt_prefix

specify a Btree prefix comparison function

options specific to BDB1::Hash

set_h_ffactor

set the Hash table density

set_h_hash

specify a hashing function

set_h_nelem

set the Hash table size

Proc given to set_bt_compare, set_bt_prefix, set_h_hash, set_store_key, set_fetch_key, set_store_value and set_fetch_value can be also specified as a method (replace the prefix set_ with bdb1_)

For example

module BDB1
   class Btreesort < Btree
      def bdb1_bt_compare(a, b)
         b.downcase <=> a.downcase
      end
   end
end

Methods

self[key]

Returns the value corresponding the key

db_get(key [, flags])

get(key [, flags])

fetch(key [, flags])

Returns the value correspondind the key

self[key] = value

Stores the value associating with key

return value

db_put(key, value [, flags])

put(key, value [, flags])

store(key, value [, flags])

Stores the value associating with key

Return the value correspondind the key

flags can have the value DBD::NOOVERWRITE, in this case it will return nil if the specified key exist, otherwise true

append(key, value)

db_append(key, value)

Append the value associating with key

byteswapped?

get_byteswapped

Return if the underlying database is in host order

close([flags])

db_close([flags])

Closes the file.

delete(key)

db_del(key)

Removes the association from the key.

It return the object deleted or nil if the specified key don't exist.

delete_if([set]) { |key, value| ... }

reject!([set]) { |key, value| ... }

Deletes associations if the evaluation of the block returns true.

Only for BDB1::Btree

duplicates(key [, assoc = true])

Return an array of all duplicate associations for key

if assoc is false return only the values.

Only for BDB1::Btree

each { |key, value| ... }

each_pair { |key, value| ... }

Iterates over associations.

each_dup(key) { |key, value| ... }

Iterates over each duplicate associations for key

Only for BDB1::Btree

each_dup_value(key) { |value| ... }

Iterates over each duplicate values for key

Only for BDB1::Btree

each_key { |key| ... }

Iterates over keys.

each_value { |value| ... }

Iterates over values.

empty?()

Returns true if the database is empty.

has_key?(key)

key?(key)

include?(key)

member?(key)

Returns true if the association from the key exists.

has_both?(key, value)

both?(key, value)

Returns true if the association from key is value

has_value?(value)

value?(value)

Returns true if the association to the value exists.

index(value)

Returns the first key associated with value

indexes(value1, value2, )

Returns the keys associated with value1, value2, ...

keys

Returns the array of the keys in the database

length

size

Returns the number of association in the database.

reject { |key, value| ... }

Create an hash without the associations if the evaluation of the block returns true.

reverse_each { |key, value| ... }

reverse_each_pair { |key, value| ... }

Iterates over associations in reverse order

Only for BDB1::Btree

reverse_each_key { |key| ... }

Iterates over keys in reverse order

Only for BDB1::Btree

reverse_each_value { |value| ... }

Iterates over values in reverse order.

Only for BDB1::Btree

to_a

Return an array of all associations [key, value]

to_hash

Return an hash of all associations {key => value}

truncate

clear

Empty a database

values

Returns the array of the values in the database.