fix: fix a bug when the same transaction inserts and deletes the same data #24
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Merge branch 'mypr' of github.com:ntw2020/TDB into mypr
ycycse
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RkGrit
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May 31, 2024
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问题：同一事务对同一数据进行插入和删除时存在bug
描述：当在一个事务中插入一条数据并删除这条数据后提交该事务，后续事务仍然可见这条数据
分析：OperationSet(aka unordered_set)由于无法区分INSERT和DELETE操作，将这两种操作判定为重复操作，因此DELETE操作不会被记录在IOperationSet中，导致虽然同学们编写的接口delete_record中将end_xid 设为对应负值，但是commit的时候没有记录这个删除操作，因此end_xid并未被设置为commit_id，仍为负值。于是影响后续visit_record。
解决办法：修改OperationSet的判断元素相等和计算哈希方法，使其能够区分对同一数据不同类型的操作。
感谢李祥瑞同学提供的图片！