sparkyen

The link for data in download_mlsys1 has been out of date

3

When I try to run : ```bash bash scripts/download_mlsys1.sh ``` I found that was failed, later I got the reson with the outdate link for data. Would you please fix...

支持MYSQL-5.7其他类别表达式（MASTER_POS_WAIT） || Supports MYSQL-5.7 other categories of expressions (MASTER_POS_WAIT)

1

### Task Description 适配mysql-5.7的表达式函数：MASTER_POS_WAIT ### Solution Description 1. 增加语法解析、词法解析和相关的流程代码 2. 增加对应的函数表达式子类并实现对应的功能 3. CMakeList增加对应的编译单元 4. 增加对应的测试文件 ### Passed Regressions ### Upgrade Compatibility ### Other Information ### Release Note --- ### Task...

### Task Description 当查询中出现重复谓词，而查询改写模块没起作用的时候，由于ob假设谓词间是独立的，直接将重复谓词的选择率相乘，会引起选择率估计过小，从而导致计划严重走偏耗时过长的情况。 例如： `select /*+no_rewrite*/ count(*) from t where (c0,c1)=(1,1) and (c1,c2)=(1,1)` 正确的计算选择率的结果是`1/(ndv*ndv*ndv)`，但是这里会将四个选择率独立相乘，即`1/(ndv*ndv*ndv*ndv)` ### Solution Description 不使用参数窥探的情况下，将表达式中的谓词进行抽取与合并，最后即可以将两个待计算选择率的表达式转化成更加精准计算的形式 ### Passed Regressions ### Upgrade Compatibility ### Other Information ### Release...

### Task Description ``` select * from t1 where c1 in (select t2.c1 from t2) and c1 in (select t2.c1 from t2, t3 where t2.c2 = t3.c2; ``` 可以做子查询合并改写 ```...

### Task Description 支持MYSQL 中 load_file表达式 ### Solution Description ### Passed Regressions ### Upgrade Compatibility ### Other Information ### Release Note