Copy views and UNIQUE constraints (0.5.0)

[dridk]

What this adds

duckdb's sqlite extension exposes neither views nor UNIQUE constraints on an attached database, so both are read back from the source with the sqlite3 module, the way the indexes already were.

Views come from sqlite_master with their SQL, translated out of sqlite's [bracket] quoting and replayed as CREATE VIEW. They land as genuine duckdb views: they show up in duckdb_views(), duckdb re-serialises the SQL as its own, and they recompute when the underlying table changes.

Two wrinkles handled:

• Their SQL is sqlite's, not duckdb's. A view using something duckdb has no equivalent for (MATCH, julianday()) is skipped with a warning rather than failing the whole conversion.
• A view sitting on another view works whatever order sqlite_master lists them in: the pass retries while it still makes progress.

UNIQUE needs a second route. A column or table level UNIQUE becomes an autoindex whose sqlite_master row carries no SQL at all, so it is invisible to the index pass. PRAGMA index_list reports it with origin = 'u' and index_info gives the columns. duckdb has no ALTER TABLE ADD CONSTRAINT, so it is replayed as a unique index, which enforces the same guarantee — the tests check that by actually trying to insert duplicates.

ConversionResult grows a views count.

Still not copied

FOREIGN KEY and CHECK. The reason first written down in 79027c8 was wrong and 61c5d00 corrects it: it is not that duckdb cannot express them. It accepts and enforces both in CREATE TABLE, the clauses inject cleanly into the DDL it already derives, and PRAGMA foreign_key_list reports them structured with no SQL to parse.

The real obstacle is loading order. duckdb checks foreign keys row by row, so a self-referencing table cannot be bulk loaded. Prototyped on chinook, nine of the thirteen tables load with their foreign keys intact; employees.ReportsTo fails and takes customers, invoices and invoice_items with it. Closing that gap needs multi pass inserts, and there is no ALTER TABLE ADD CONSTRAINT to add the keys after the data.

Verification

32 tests to 38, including a deliberately untranslatable view checking the graceful degradation, and duplicate inserts checking that UNIQUE is really enforced rather than merely present. CI green on 3.9 through 3.13.

Version 0.4.0 to 0.5.0.

🤖 Generated with Claude Code

https://claude.ai/code/session_01XtZtVXPQqXvdHLQ98bT2gF