Tokyo Cabinet乱贴(未整理,仅供自己做笔记)

[size=large]网上关于Tokyo Cabinet的简介(http://www.162cm.com/archives/681.html)

项目主页:http://tokyocabinet.sourceforge.net/

Tokyo Cabinet 是一个DBM的实现。这里的数据库由一系列key-value对的记录构成。key和value都可以是任意长度的字节序列,既可以是二进制也可以是字符串。这里没有数据类型和数据表的概念。

当做为Hash表数据库使用时，每个key必须是不同的,因此无法存储两个key相同的值。提供了以下访问方法:提供key,value参数来存储，按 key删除记录，按key来读取记录，另外，遍历key也被支持，虽然顺序是任意的不能被保证。这些方法跟Unix标准的DBM,例如GDBM,NDBM 等等是相同的，但是比它们的性能要好得多(因此可以替代它们)

当按B+树来存储时，拥用相同key的记录也能被存储。像hash表一样的读取，存储，删除函数也都有提供。记录按照用户提供的比较函数来存储。可以采用顺序或倒序的游标来读取每一条记录。依照这个原理，向前的字符串匹配搜索和整数区间搜索也实现了。另外，B+树的事务也是可用的。

As for database of fixed-length array, records are stored with unique natural numbers. It is impossible to store two or more records with a key overlaps. Moreover, the length of each record is limited by the specified length. Provided operations are the same as ones of hash database.

对于定长的数组，记录按自然数来标记存储。不能存储key相同的两条或更多记录。另外，每条记录的长度受到限 制。读取方法和hash表的一样。

Tokyo Cabinet是用C写的，同时提供c,perl,ruby,java的API。Tokyo Cabinet在提供了POSIX和C99的平台上都可用，它以GNU Lesser Public License协议发布。

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囧,没有python,网上有一个python bind,不过不好使.还是自己封装靠谱

先看看文档 和 example

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文档节选

Tokyo Cabinet runs very fast.

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1 million records is 1.5 seconds for hash database, and 2.2 seconds for B+ tree database. Moreover, the size of database of Tokyo Cabinet is very small. For example, overhead for a record is 16 bytes for hash database, and 5 bytes for B+ tree database.

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The database size can be up to 8EB (9.22e18 bytes).

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Due to this simple structure, fixed-length database works faster than hash database, and its concurrency in multi-thread environment is prominent.

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Every operation for database is encapsulated and published as lucid methods as `open' (connect), `close' (disconnect), `put' (insert), `out' (remove), `get' (retrieve)

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That is, while a writing thread is operating the database, other reading threads and writing threads are blocked. However, while a reading thread is operating the database, reading threads are not blocked.