I'm pretty sure SQLite has covering indexes. And the relatively new strict mode should enforce at least basic types (though if you want to enforce your own rules for things like dates you're still on your own).
I checked to be sure I had not missed it, and didn’t find anything. You have expressions and conditions, but no covering. Obviously you can kinda emulate it by adding the columns you want to cover to the key, but…
> though if you want to enforce your own rules for things like dates you're still on your own
That’s what I was talking about, having richer types, and the ability to create more (especially domains).
Strict tables provides table stakes of actually enforcing the all-of-5-types sqlite has built-in. Afaik a strict mode is something that’s still being discussed if it ever becomes reality.
Right, that seems like a good solution to me.
My impression is that this mechanism is less general than what one finds in full-fat client-server SQLite databases.
I guess it's less of an issue in sqlite than in databases with richer datatypes in the sense that all datatypes are ordered and thus indexable.
CREATE INDEX tab_x_y
ON tab(x) INCLUDE (y);- it's not constrained (e.g. to be orderable)
- it does not affect the behaviour of the index, so you can have covering data in a UNIQUE index, or in a PK constraint (although for the latter one might argue a clustered index is superior)
- it only takes space in leaf nodes, not interior nodes, so you can have better occupancy of interior node pages, less pages to traverse during lookup, and they have better cache residency
- and finally the intent is clearer, when you put everything in the key it does not tell the reader what's what and why it there, and thus makes it harder to evaluate changes