logical plan & physical plan;
explain;
yacc rewrite;
join operator(nested loop join);
simple rewrite rules;
fix some issues of mysql protocol;

tested by mariadb ( Ver 15.1 Distrib 5.5.65-MariaDB, for Linux (x86_64) using readline 5.1)
but failed with obclient

2022 oceanbase competition

* support build with address sanitizer

using cmake options `-DENALBE_ASAN=ON` to enable address sanitizer

* fix some memory leaks detected by asan

* fix -Wunused-function

* 调整文档格式

优化load data效率

format lex file

Docker 中安装gdb；
删除handler.h 文件；
BplusTree中的比较函数使用deps下公用接口；

修复进程退出时，libevent 无法正常结束循环的BUG

remove unused variable

set response to failure while resolve failed

1. select return all columns;
2. no tuple header now;
3. predicate works now.

重构disk buffer pool：
新增BufferPoolManager，管理所有的DiskBufferPool；
原有DiskBufferPool只处理一个文件，取消其中file_id的概念；
删除BPPageHandle，直接使用Frame；
BPManager更名BPFrameManager；
BPFileSubHeader改为BPFileHeader并直接放在DiskBufferPool中