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1. 发明授权

US5412384A Method and system for adaptively building a static Ziv-Lempel dictionary for database compression 失效
标题翻译：用于自适应构建静态Ziv-Lempel字典进行数据库压缩的方法和系统
公开(公告)号：US5412384A
公开(公告)日：1995-05-02
申请号：US288675
申请日：1994-08-10
申请人： Chung-Chia Chang , Gregory L. Davoll , Mohamed H. El-Ruby , Craig A. Friske , Balakrishna R. Iyer , John P. Lazarus , David Wilhite , Kenneth E. Plambeck
发明人： Chung-Chia Chang , Gregory L. Davoll , Mohamed H. El-Ruby , Craig A. Friske , Balakrishna R. Iyer , John P. Lazarus , David Wilhite , Kenneth E. Plambeck
IPC分类号： G06F5/00 , G06T9/00 , H03M7/30 , H03M7/46 , H03M7/38
CPC分类号： H03M7/3088 , G06T9/005
摘要： A system for creating a static data compression dictionary adapted to a hardware-based data compression architecture. A static Ziv-Lempel dictionary is created and stored in memory for use in compressing database records. No data compression occurs during dictionary construction. A fixed-size Ziv-Lempel parse-tree is adapted to database characteristics in one of two alternate ways. First, the parse-tree is overbuilt substantially and then pruned back to a static size by eliminating the least recently used (LRU) nodes having the lowest use count. Alternatively, the parse-tree is built to a static size and thereafter selected nodes are replaced with new nodes upon database sampling. This node recycling procedure chooses the least-useful nodes for replacement according to a use count and LRU strategy while exhausting the database sample. The pruned Ziv-Lempel parse-tree is then transformed to a static dictionary configuration and stored in memory for use in a hardware-based database compression procedure. Completion of the static dictionary before starting data compression eliminates the initial compression inefficiencies well-known for the Ziv-Lempel procedure. The parse-tree construction is enhanced by initializing the tree with NULL and DEFAULT sequences from database definitions before examining any data.
摘要翻译：一种用于创建适用于基于硬件的数据压缩架构的静态数据压缩字典的系统。静态Ziv-Lempel字典被创建并存储在内存中用于压缩数据库记录。字典构造期间不发生数据压缩。固定大小的Ziv-Lempel解析树以两种备选方式之一适用于数据库特征。首先，解析树被大量覆盖，然后通过消除具有最低使用次数的最近最少使用的（LRU）节点将其修剪回静态大小。或者，解析树被构建为静态大小，此后在数据库采样时，所选择的节点被新节点替换。该节点回收过程根据使用次数和LRU策略选择最不利的节点进行替换，同时耗尽数据库样本。修剪后的Ziv-Lempel解析树然后转换为静态字典配置，并存储在内存中，用于基于硬件的数据库压缩过程。开始数据压缩之前完成静态字典消除了Ziv-Lempel过程众所周知的初始压缩效率低下。在检查任何数据之前，通过从数据库定义中初始化具有NULL和DEFAULT序列的树来增强解析树结构。

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