发明名称 |
Database management system, and query method and query execution program in the database management system |
摘要 |
The present invention relates to an optimization method in a database management system having the function of accessing external databases. Conventionally, whether functions contained in a query can be executed in external databases depends on a database management system having the functions, and therefore there has been a problem in that a database utilization method cannot apply to query optimization and query execution performance is reduced. To solve the above problem, a database management system having the function of accessing external databases is provided with an optimization step comprising the steps of: obtaining specification about whether to execute functions in a query in external databases; determining whether data referred to in a query is confined to one database; and determining whether a user specifies that the functions in the query are executed in external databases.
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申请公布号 |
US6925462(B2) |
申请公布日期 |
2005.08.02 |
申请号 |
US20020041577 |
申请日期 |
2002.01.10 |
申请人 |
HITACHI, LTD. |
发明人 |
NISHIKAWA NORIFUMI;INOHARA SHIGEKAZU;SHIMAZAKI KOICHI;HIROHATA KIYOMI;YAMAHIRA KOHSAKU;HAYASHI SHIGETOSHI |
分类号 |
G06F12/00;G06F17/30;(IPC1-7):G06F17/30 |
主分类号 |
G06F12/00 |
代理机构 |
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代理人 |
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地址 |
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