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1. 发明授权

US06263331B1 Hybrid hash join process 失效
标题翻译：混合哈希连接过程
公开(公告)号：US06263331B1
公开(公告)日：2001-07-17
申请号：US09135313
申请日：1998-07-30
申请人： Lee-Chin Hsu Liu , Lowell L. Baerenwald , James M. Plasek , Michael S. Jende , Kenji Yoneda
发明人： Lee-Chin Hsu Liu , Lowell L. Baerenwald , James M. Plasek , Michael S. Jende , Kenji Yoneda
IPC分类号： G06F1700
CPC分类号： G06F17/3048 , G06F17/30498 , Y10S707/99933 , Y10S707/99934
摘要： A hybrid hash join process joins data rows from two tables which have at least one common data column by partitioning the data rows based on the values in the common data column(s), creating data structures to decrease search time for matching rows, and recovering full data buffers using a unique buffer management methodology. A smaller one of the two tables is designated as an outer table and a larger one of the two tables as an inner table. The hybrid hash join process determines which rows in the inner and outer tables satisfy a selection criteria; the rows that satisfy the selection criteria are referred to as inner hit rows and outer hit rows. The hybrid hash join process assigns the inner and outer hit rows to corresponding inner and outer partitions, respectively. Buffer overflow in the outer partitions is handled by linking empty buffers to the outer partitions until all buffers are used. Buffer space is recovered by writing outer hit rows for a selected partition to mass storage. Buffer overflow in the inner partitions is handled by either writing the inner rows in the buffer to mass storage or by searching the corresponding outer partition for matches. The outer hit rows in the corresponding outer partition are allocated to entries in a data structure which is then probed to find matches for the inner hit rows in the buffer. Matching outer hit rows for any inner hit rows written to mass storage are found by repeatedly reading into memory inner and outer hit rows and probing a data structure created from the memory-resident outer hit rows in a partition. Optionally, binary trees are built from the entries in the data structure to speed up the probing procedure. The hybrid hash join process uses at least one hashing algorithm to assign hit rows to partitions, to allocate rows to entries in the data structures, and to probe the data structures for matches.
摘要翻译：混合散列连接过程通过基于公共数据列中的值划分数据行，从具有至少一个公共数据列的两个表中连接数据行，创建数据结构以减少匹配行的搜索时间，并且恢复全数据缓冲区使用独特的缓冲区管理方法。两个表中较小的一个表被指定为外部表，两个表中较大的一个作为内部表。混合散列连接过程确定内表和外表中的哪些行满足选择标准; 满足选择条件的行被称为内部命中行和外部命中行。混合散列连接过程分别将内部和外部命中行分配给相应的内部和外部分区。外部分区中的缓冲区溢出通过将空缓冲区链接到外部分区来处理，直到使用所有缓冲区。通过将所选分区的外部命中行写入大容量存储来恢复缓冲区空间。内部分区中的缓冲区溢出通过将缓冲区中的内部行写入大容量存储或通过搜索相应的外部分区进行匹配来处理。相应的外部分区中的外部命中行被分配给数据结构中的条目，然后被探测以找到缓冲区中的内部命中行的匹配。通过重复读入存储器内部和外部命中行并探测从分区中的存储器驻留的外部命中行创建的数据结构，找到写入大容量存储的任何内部命中行的匹配外部命中行。可选地，从数据结构中的条目构建二进制树，以加速探测过程。混合散列连接过程使用至少一个散列算法来将命中行分配给分区，以将行分配给数据结构中的条目，并探索数据结构以进行匹配。

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