I'm facing a hard time trying to figure it out some performance problems in my database. I'm using a bunch of resources online to learn what to monitor and how to interpret that information.
From the above, I'm unable to find a clear explanation of what is the difference between
In pgAdmin4, there is a beautiful chart called "Tuples out" where these two concepts are contrasted, but I don't know how to interpret the info. In the official documentation only says that:
tup_returned: Number of rows returned by queries in this database
tup_fetched: Number of rows fetched by queries in this database
What exactly does "fetched" and "returned" mean?
I'm using postgresql 10.