-
Notifications
You must be signed in to change notification settings - Fork 2
/
project.cpp
63 lines (56 loc) · 1.56 KB
/
project.cpp
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
#include "utils.cpp"
#pragma once
/**
* @brief 投影操作
* 投影R表中的非主码A属性
*/
const addr_t projStart = 2000; // 投影结果的其实存放地址
/**
* @brief 投影
* 从读取的表中抽取每一条记录的A属性写入结果
*
* @param projTable 待投影表的信息
* @param resTable 投影结果表的信息
*/
void project(table_t projTable, table_t &resTable) {
block_t blk, resBlk;
row_t t_read, t_write;
addr_t curAddr = 0;
blk.loadFromDisk(projTable.start);
resBlk.writeInit(resTable.start);
bool isLastRow = false;
while(1) {
t_read = blk.getNewRow();
if(t_read.isFilled == false) {
addr_t endAddr = resBlk.writeLastBlock();
if (endAddr != END_OF_FILE)
curAddr = endAddr;
break;
}
t_write.A = t_read.A;
t_read = blk.getNewRow();
if(t_read.isFilled == false) {
t_write.B = MAX_ATTR_VAL;
isLastRow = true;
} else {
t_write.B = t_read.A;
}
resBlk.writeRow(t_write);
resTable.size += 1;
}
addr_t endAddr = resBlk.writeLastBlock();
if (endAddr != END_OF_FILE)
curAddr = endAddr;
resTable.end = curAddr;
}
/**************************** main ****************************/
// int main() {
// bufferInit();
// table_t projRes(projStart);
// project(table_R, projStart);
// showResult(projStart, sizeOfRow / 2);
// printf("\n注:结果写入磁盘块:%d-%d\n", projRes.start, projRes.end);
// printf("本次共发生%ld次I/O\n", buff.numIO);
// system("pause");
// return OK;
// }