pub enum Behaviour {
Honoured,
Knob(&'static str),
DefaultOnly(&'static str),
}Expand description
What the engine does with a value handed to a setting.
The three cases are not three degrees of the same thing. The first is a setting rudb reads, the second is one nothing could read because there is nothing for it to change, and the third is one that would need reading and has nowhere yet to be read.
Variants§
Honoured
rudb acts on it. The value lives in the engine rather than in this table, which is why this case carries none.
Knob(&'static str)
A knob, with the value a database that has set nothing reports for it.
Nothing it can be set to changes what a query returns, so rudb takes it, keeps it and hands
it back, and the statement after it runs the way it would have anyway. SET enable_http_metadata_cache = true is this: there is no HTTP metadata cache here, there is
nothing a query could notice about whether one is on, and a script that sets it wanted to
keep going rather than to be told rudb has never heard the name.
DefaultOnly(&'static str)
Something rudb does not do, with the one value it already behaves as.
Setting it to anything else is refused. SET preserve_insertion_order = false is this: it is
a real change to what a query returns, rudb cannot make it, and taking the value and not
acting on it would turn one clear error into a wrong answer a statement later.