【摘要】 目前,我国地震前兆数据库采用Oracle数据库管理系统,每天每种采样类型观测值存储在Clob类型字段的一个纪录中。对比了将观测数据存储在Clob和Blob类型字段中数据的存取速度,发现将观测数据存储在Blob类型字段中具有更高的效率。主要有两个原因:一是利用API函数Copymemory在内存里实现数据传输,二进制数据比字符串型数据存取快;二是数据存储在Blob类型中占用更少的空间,网络传输快。更多还原

【Abstract】 At present,earthquake precursor database in China uses the Oracle database management system.Each kind of sampling type observation data in a day stores in a record of field with Clob type.Contrasted the access speed of observation data stored in Clob and in the Blob type field,and discovered that observation data storing in the Blob type field has higher access efficiency.This mainly has two reasons: One is that the binary data access is quicker than string data using API function Copymemory to realize the data transmission in the memory,the other is the data stored in the Blob type takes less spaces,so the network transmission takes less time.更多还原