It really feels like the DB industry has taken a huge step backward from the promise of SQL. Switching from Postgres to SQLite is easy because the underlying queries are at least similar. But as soon as you introduce embeddings, every system is totally different (and often changing rapidly).
Specialized vector indexes become important when you have a large number of vectors, but the reality of software is that it is unlikely that your application will ever be used at all, let alone reach a scale where you start to hurt. Computers are really fast. You can go a long way with not-perfectly-optimized solutions.
Once you have proven that users actually want to use your product and see growth on the horizon to where optimization becomes necessary, then you can swap in a dedicated vector solution as needed, which may include using a vector plugin for SQLite. The vector databases you want to use may or may not use SQL, but the APIs are never that much different. Instead of one line of SQL to support a different implementation you might have to update 5 lines of code to use their API, but we're not exactly climbing mountains here.
Know your problem inside and out before making any technical choices, of course.
There are plenty of proprietary databases and APIs, but now you're taking on a dependency and assuming a certain amount of risk.
Be the change you want to see, I suppose. No doubt convergence will come, but it is still early days. Six months ago, most developers didn't even know what a vector database is, let alone consider it something to add to their stack.
It took SQL well into the 1990s to fully solidify itself as "the standard" for relational querying. Even PostgreSQL itself was started under the name POSTGRES and was designed to use QUEL, only moving over to SQL much later in life when it was clear that was the way things were going. These things can take time.
IBM had SQL in their database product in 1981, Oracle had it by v4 in 1984, ANSI picked SQL as its standard that same year, and completed the first version by 1986.
Some time scientists say that the 1980s occurred before "well into the 1990s" but I mean, who can really say, right?
We're done here.
Of course, if there's a shortcoming of sqlite that I know I need right out of the gate, that would be a situation where I start with postgres.
https://supabase.com/docs/guides/database/extensions/pgvecto...
This is the new kid in town so you would see soon all major SQL dbs will support vector. However, any serious user, O(10M) vectors or above, would still require a dedicated vector db for performance reasons.