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OceanBase 数据库大赛:唯一索引 思路分析

2023-03-15 21:59:53 时间

PICK OF THE WEEK

一、最少知识(可以看视频)

  1. lectures-on-dbms-implementation
  • https://oceanbase-partner.github.io/lectures-on-dbms-implementation/lecture-2
  • 第2章 数据库的存储结构
  1. 2019CMU数据库导论(intro to database systems fall 2019) - https://www.bilibili.com/video/BV1U7411K7TM?p=8 - https://www.bilibili.com/video/BV1U7411K7TM?p=3
  • CMU15 445/645课程-Tree Based Indexes笔记
  • CMU 15-445 Fall 2020 Labs 实现笔记
  • https://cs.carleton.edu/faculty/awb/cs334/s21/projects/project1.html
  1. OceanBase 数据库大赛
  • OceanBase 数据库大赛(第五期直播回放) https://www.bilibili.com/video/BV1u34y1m7G5
  • OceanBase 数据库大赛(第四期直播回放) https://www.bilibili.com/video/BV1wg411F7zm
  • OceanBase 数据库大赛(第三期直播回放) https://www.bilibili.com/video/BV1GP4y1h7tZ
  • OceanBase 数据库大赛(第二期直播回放) https://www.bilibili.com/video/BV1pq4y1f7BT (这个一定要看)
  1. b+ tree的查找逻辑:

提示:这里为什么一定区分叶子节点呢 https://en.wikipedia.org/wiki/B%2B_tree

二、思路分析

  1. 如果证明这个这个索引是普通索引 还是唯一索引呢?TableMeta 插入时候 如何判断重复呢?
  2. 测试对比发现:插入一个记录 不提示 节点重复,更新索引:提示节点重复,他们之间差别 就不同的page? 对比插入逻辑 和更新逻辑
  3. 有人知道 slot_num是干啥用的不? https://oceanbase-partner.github.io/lectures-on-dbms-implementation/lecture-2
  4. b+ 查找和插入算法描述是什么?

三、代码实现

##      插入逻辑 和索引的关系

case SCF_INSERT:

make_record(value_num, values, record_data);

Operation::Type::INSERT



index->insert_entry(record, &rid);


  

## 更新和索引的关系
## 更新和索引的关系

case SCF_UPDATE:
  
  RC Table::commit_update(T
                          
                          
  Record oldrecord;
  rc = record_handler_->get_record(&rid, &oldrecord);
  
  
  RC Table::scan_record_by_index(T
  
      RC Trx::commit() {
  
    RID rid;
      rid.page_num = operation.page_num();
      rid.slot_num = operation.slot_num();
  
  
RC Table::commit_insert(Trx *trx, const RID &rid)


rc = index->insert_entry(oldrecord.data, &oldrecord.rid);
/**
   * 获取指定文件中标识符为rid的记录内容到rec指向的记录结构中
   * @param rid
   * @param rec
   * @return
   */
  RC get_record(const RID *rid, Record *rec);   
                                 
## 查找和索引的关系

case SCF_SELECT:

RC SelectExeNode::execute(TupleSet &tuple_set) 

return scan_record(trx, filter, limit, (void *)&adapter, scan_record_reader_adapter);
                   
IndexScanner *Table::find_index_for_scan(const DefaultConditionFilter &filter)

RC Table::scan_record_by_index(
  
  RC BplusTreeHandler::insert_entry(const char *pkey, const RID *rid) {
  
  
  
## 插入一行记录 case SCF_INSERT:

Table::insert_record(Trx *trx, int value_num, const Value *values) 

Record

RC BplusTreeHandler::insert_entry(const char *pkey, const RID *rid) {

  class BplusTreeIndex : public Index {
    
    RC BplusTreeHandler::insert_entry(const char *pkey, const RID *rid) 
    
    RC BplusTreeScanner::open
    
   ## 干啥呢
    int CmpKey(AttrType attr_type, int attr_length, const char *pdata, const char *pkey)
{
  int result = CompareKey(pdata, pkey, attr_type, attr_length);
  if (0 != result) {
    return result;
  }
  RID *rid1 = (RID *) (pdata + attr_length);
  RID *rid2 = (RID *) (pkey + attr_length);
  return CmpRid(rid1, rid2);
}
    
    RC BplusTreeHandler::insert_into_leaf(PageNum leaf_page, const char *pkey, const RID *rid)
    
    参考:更新逻辑
   rc = index->insert_entry(oldrecord.data, &oldrecord.rid);
f(rc ==RC::RECORD_DUPLICATE_KEY)
      {
        rc =RC::SUCCESS;
      }    
    
    RC BplusTreeScanner::next_entry(RID *rid) {

四、调试

## 查找叶子节点
breakpoint set --file bplus_tree.cpp --line 284
breakpoint set --file bplus_tree.cpp --line 818
breakpoint set --file default_storage_stage.cpp --line 239



insert into t values(1,11, "a","2021-3-1",1.1);

update t set birthday='2021-3-11'  where   birthday='2021-3-11';

unique: result file difference(`-` is yours and `+` is base)
 1. UNIQUE TEST
 CREATE UNIQUE INDEX INDEX_ID ON UNIQUE_TABLE(ID);
 SUCCESS
 INSERT INTO UNIQUE_TABLE VALUES (2,1,1);
 SUCCESS
 CREATE UNIQUE INDEX INDEX_ID ON UNIQUE_TABLE(ID);
 FAILURE
 INSERT INTO UNIQUE_TABLE VALUES (3,2,1);
 SUCCESS
 INSERT INTO UNIQUE_TABLE VALUES (1,2,1);
-SUCCESS
+FAILURE

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