w******1 发帖数: 520 | 1 什么是BITMAP, 怎么个结构啊?
看到很多人在讨论BITMAP, 可是GOOGLE BITMAP, 出来的结果都不是算法啊, 都是图
像处理的。
用128MB的内存做一个BitMap~
然后把原来的文件遍历一次,每读一个数都在上述BitMap中标记~按位取或预算~
索引就是这个数字的大小~结束后,扫描bitMap,找到没有标记的即可~
for(unsigned int i=0;i<0xffffffff;i++){ unsigned temp=next integer from
inputfile; bitmap[temp]=1;}for(unsigned int i=0;i<0xffffffff;i++){
if(bitmap[i]==0) output(i);} 4个月前 by rex.nani
关于代码格式化:把代码的那一部分部分全选,然后点击101010按钮 -
又:4Billion的内容,128M是不够的 -
@半瓶墨水: 128MByte*8=1Gbits=2^32 按位存的话是可以的吧~ -
@rex |
a*********9 发帖数: 523 | 2 你说的是BITSET吧,可以查查C++的相关资料。
BITMAP在图象里是另一个概念了。
from
【在 w******1 的大作中提到】 : 什么是BITMAP, 怎么个结构啊? : 看到很多人在讨论BITMAP, 可是GOOGLE BITMAP, 出来的结果都不是算法啊, 都是图 : 像处理的。 : 用128MB的内存做一个BitMap~ : 然后把原来的文件遍历一次,每读一个数都在上述BitMap中标记~按位取或预算~ : 索引就是这个数字的大小~结束后,扫描bitMap,找到没有标记的即可~ : for(unsigned int i=0;i<0xffffffff;i++){ unsigned temp=next integer from : inputfile; bitmap[temp]=1;}for(unsigned int i=0;i<0xffffffff;i++){ : if(bitmap[i]==0) output(i);} 4个月前 by rex.nani : 关于代码格式化:把代码的那一部分部分全选,然后点击101010按钮 -
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w******1 发帖数: 520 | 3 谢谢楼上。我看答案是 bitmap
不是BITSET, BITSET 是位的操作吧 |
w******1 发帖数: 520 | 4 7) Explain about the role of bitmap indexes to solve aggregation problems?
Bitmaps are very useful in start schema to join large databases to small
databases. Answer queries and bit arrays are used to perform logical
operations on the databases. Bit map indexes are very efficient in handling
Gender differentiation; also repetitive tasks are performed with much larger
efficiency.
8) Explain about Encoding technique used in bitmaps indexes?
Bitmaps commonly use one bitmap for every single distinct |
w******1 发帖数: 520 | 5 OLAP - role of bitmap indexes to solve aggregation problems - March 08, 2009
at 22:00 PM by Rajmeet Ghai
Explain the role of bitmap indexes to solve aggregation problems.
Bitmap indexes are useful in connecting smaller databases to larger
databases. Bit map indexes can be very useful in performing repetitive
indexes. Multiple Bitmap indexes can be used to compute conditions on a
single table.
OLAP - role of bitmap indexes to solve aggregation problems - Jan 10, 2010
at 18:50 PM by Vidya Sagar
E |
w******1 发帖数: 520 | 6 On Memory Management of Tree-bitmap
Algorithm for IP Address Lookup
http://www.academypublisher.com/proc/iscsct09/papers/iscsct09p418.pdf |
v****s 发帖数: 1112 | 7 bit map is also called bit array |
x**********n 发帖数: 1262 | |
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w******1 发帖数: 520 | |
s**y 发帖数: 151 | 10 他们讨论的是Bit-Map,不是Bitmap. |