预期时间效率
我有 2 个数据库文件，在其中我必须搜索，我使用了 4 种方法，即：内存中顺序、内存中二进制、磁盘顺序和磁盘二进制。需要搜索的文件大小为20Kb。这 4 个程序的预期运行时间应该是
磁盘顺序> 。磁盘二进制>内存中顺序>内存中的二进制文件 但它的结果是 磁盘二进制文件>磁盘顺序>内存中顺序>内存中的二进制文件。
磁盘二进制比磁盘顺序多花费大约 1.5 秒。为什么会这样呢？ 我计算的时间是打印打开文件之前的时间以及打开文件并进行搜索之后的时间。
谢谢！
I have 2 database files and among those one I had to search for which I used 4 methods namely: in-memory sequential, in-memory binary, disk sequential and disk binary. The file which needed to be searched was 20Kb in size. The expected running time for these 4 programs should have been
disk sequential > disk binary > in-memory sequential > in-memory binary but its coming out to bedisk binary > disk sequential > in-memory sequential > in-memory binary.
Disk binary is taking around 1.5 sec more than the disk sequential. Why so?
I have calculated the time as printing the time before opening the file and then after opening the file and doing the search.
Thanks!
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这可能取决于文件的大小；磁盘与主内存不同，它被划分为多个块，并且您的文件可能不会大于 20 个块。
所以 log_2(20) 约为 5，然后二分搜索不会更好，除非您要搜索的内容是在第五个块之后。
It can depends on the small size of your file; disk is not like main memory, it's divided in blocks and your file won't be probably bigger than 20 blocks.
So log_2(20) is about 5 and then binary search won't be better unless what you're searching for is after the fifth block.