Sakura-gh / naivedb

NaiveDB

IndexManager

implemented by gehao, 2020/5/30

introduction

This template class BPlusTree.h implemented most functions of bplustree. It's suitable for any order and any data type.

Now I have used BPlusTree.h to Implement function interface for minisql with file management:

• IndexManager.h and IndexManager.cpp：the interface for minisql
• BPlusTree.h：implement the bplustree and store {key: value} in file named ./index/
• basis.h and basis.cpp：give some basis enum, struct, const and function

attention!

this code runs in Linux, and for other os, you need to modify a little in BPlusTree.h：

• for #include in linux：

#include <unistd.h> 
#include <sys/stat.h> 

change to (in other os):

#include <io.h>
#include <direct.h>

• for void BPlusTree<T>::_init_from_disk() in Linux

if (access(_fileName.c_str(), 0) != -1){...}

change to (in other os):

if (_access(_fileName.c_str(), 0) == -1){...}

• for void BPlusTree<T>::_write_disk() in Linux

// if dir not exists, mkdir
if (access(_dir.c_str(), 0) == -1)
    mkdir(_dir.c_str(), S_IRWXU | S_IRWXG | S_IROTH | S_IXOTH);

change to (in other os):

if (_access(_dir.c_str(), 0) == -1)
    _mkdir(_dir.c_str());

compile and test

for Linux/macos/unix:

exec.sh can automatically find all the .cpp files and compile them into .o executable file, run finally

test.cpp gives a simple test for BPlusTree.h

• if INDEX_test file in dir ./index/ not exists , it will create bplustree with insert 0-49 firstly and delete 0-19 later, finally it will store the {key:value} in ./index/INDEX_test
• if INDEX_test file in dir ./index/ exists, it will read the {key: value} from this file and build bplustree automatically, after that, it wll print node's key in all tree level.

the method to compile and run the code in exec.sh: (open your ternimal firstly)

$ bash exec.sh 
please enter the executable file name: test # you need to enter test or other file name you like to generate execuable file
g++ basis.cpp IndexManager.cpp test.cpp -std=c++11 -o test.o # some information
compile...
./test.o
execute...
# if ./index/INDEX_test not exists
-------------------------insert(0-49)--------------------------
18   
6 12   24 30 36 42   
2 4   8 10   14 16   20 22   26 28   32 34   38 40   44 46   
0 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  
-------------------------delete(0-19)--------------------------
30 36 42   
22 24 26 28   32 34   38 40   44 46   
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 

# if ./index/INDEX_test exists
# just print the tree stored in file
26 32 38   
22 24   28 30   34 36   40 42 44 46   
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  

for windows (modify BPlusTree.h mentioned above firstly !):

you need to enter in cmd manually

g++ basis.cpp IndexManager.cpp test.cpp -std=c++11 -o test.o
./test.o

others

useful website: https://www.cs.usfca.edu/~galles/visualization/BPlusTree.html