Comment by fc417fc802
2 months ago
Note that "some information related to the file layout" or "some information that has an impact on the file layout" is not "the file layout" in a literal sense. Thus it seems to me to follow that the answer to the question "is this a file layout" should be no.
Symbolically it isn't [ schema -> file layout ] it's [ schema, engine version -> file layout ]. Even if you had that additional information, neither item by itself nor even the pair together would be correctly considered a file layout. If I have a function f( foo, bar ) -> baz neither a foo nor a bar is a baz. I can fairly trivially fix a sandwich out of bread, peanut butter, and jam; in no way does that imply that the three ingredients sitting next to each other on the counter are a sandwich.
For that matter, even the [ schema -> file layout ] case isn't technically a file layout any more than a json blob is an xml blob. Being trivially translatable doesn't change the definition.
Compare that with the question (also commonly asked by courts) "is thing equivalent in intent (or use, or ...) to other thing" in which case the answer might feasibly be yes.
> Could you really claim the schema didn't contain any file layout information in that scenario, when it certainly affected which bytes are interpreted as belonging to which columns?
In that example you have made an educated guess about the file layout and then taken advantage of that (guessed) information. "You can imagine a database" tells you everything you need to know here, namely that this is entirely dependent on the implementation. So yes, I would claim that the schema did not on its own contain any file layout information though in conjunction with knowledge of the implementation it could be used to derive such.
> I can fairly trivially fix a sandwich out of bread, peanut butter, and jam; in no way does that imply that the three ingredients sitting next to each other on the counter are a sandwich.
What is "sandwich" in this analogy? Nobody is claiming the schema is a "database", or a "table". I was saying it's one component of the file layout.
Using your own analogy: if you know you put the jam near the peanut butter, you know part of the ingredient layout. You can't say "it's not ingredient layout if you haven't told me where the bread is."
The point about the sandwich was that the inputs to a function are not correctly referred to as its output. Those are distinct things.
If you wanted to further extend the analogy to apply to schemas then I guess the recipe would be the database engine and the final product that you eat would be the file layout. Knowing that the final dish will include jam does not mean that you have the final dish in your possession. The jam sitting on the counter is not the final dish.
Importantly, you don't even know how I'm going to use the jam. I could put it only on one half, or I could arrange it in stripes, or I could even use more than two pieces of bread! I might not even make a sandwich! I could even throw it all in a blender and make a (disgusting) smoothie.