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unkulunkulutoday at 5:13 PM1 replyview on HN

> At this stage, it has nothing to do with xmin and xmax, but rather because other transactions cannot see uncommitted data

Am I missing something or this statement is incomplete? Also I find the visualization of commit weird, it “points to” the header of the table, but then xmax gets updated “behind the scenes”? Isnt xmax/xmin “the mechanism behind how the database knows what is committed/not committed”? Also, there could be subtransactions, which make this statement even more contradictory?

I enjoyed the visualizations and explanations otherwise, thanks!


Replies

CWIZOtoday at 8:26 PM

I also think the article glossed/skipped over the xmax/xmin concepts. And they are fundamental to understand how different isolation levels actually work. It's quite jarring to the point I'm wondering if a whole section got accidentally dropped from the article.