Hi hackers,
I am currently working on improving the cardinality estimation component in PostgreSQL with machine learning. I came up with a solution that mutates the bounds for different columns. For example, assume that we have a query
```
select * from test where X<10 and Y<20;
```
Our approach tries to learn the relation between X and Y. For example, if we have a linear relation, Y=X+10. Then Y<20 is essentially equivalent to X<10. Therefore we can mutate the Y<20 to Y<INT_MAX so that the selectivity will be 1, and we will have a more accurate estimation.
It seems to me that we can achieve something similar by mutating the pg_statistics, however, mutating the bounds is something more straightforward to me and less expensive.
I am wondering if it is possible to have such an extension? Or if there is a better solution to this? I have already implemented this stuff in a private repository, and if this is something you like, I can further propose the patch to the list.
Best regards,
Xiaozhe