# SQLite -> PostgreSQL virtual table (minimal)

This directory contains a minimal SQLite extension that implements a read-only virtual table backed directly by PostgreSQL using libpq.

Build
-----
You need `libpq` (Postgres client) and a C compiler. On Debian/Ubuntu:

```bash
sudo apt-get install libpq-dev build-essential
make
```

This produces `pg_vtab.so`.

Usage
-----
Start `sqlite3`, load the extension and create a virtual table pointing at a Postgres table:

```sql
.load ./pg_vtab.so
CREATE VIRTUAL TABLE remote_tbl USING pg_vtab('host=localhost dbname=mydb user=me password=secret', 'public.mytable');
SELECT * FROM remote_tbl LIMIT 10;
```

Limitations
-----------
- Minimal proof-of-concept: supports only full table scans.
- All columns are presented as `TEXT`.
- No constraint pushdown or type mapping sophistication.
- Error handling and SQL injection hygiene are minimal; do not use on untrusted inputs without review.

Next steps (optional)
---------------------
- Add support for WHERE constraints and indexed access (`xBestIndex`).
- Map Postgres types more accurately to SQLite storage classes.
- Implement server-side cursors for large tables.
- Harden error reporting and resource cleanup.