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MountSQLiMountSQLI

Postgres

@mountsqli/driver-postgres wraps pg. It uses $N parameter style and a connection pool with per-call borrow().

Install & use

Section titled “Install & use”
Terminal window
pnpm add @mountsqli/driver-postgres pg
import "@mountsqli/driver-postgres";
import { mountsqli } from "@mountsqli/core";


const db = mountsqli({
  driver: "postgres",
  url: process.env.DATABASE_URL!,
  tables: [users],
});

Parameter style

Section titled “Parameter style”

The dialect compiles plans to $N parameters:

SELECT * FROM "users" WHERE "age" > $1

Per-call borrow()

Section titled “Per-call borrow()”

borrow() returns a self-contained client handle. Each query() takes and releases its own pooled client — borrows never clobber each other (issue 002).

const handle = await driver.borrow();
try {
  await handle.query("SELECT 1", []);
} finally {
  await handle.release();
}

Transactions

Section titled “Transactions”
await db.transaction(async (tx) => {
  await tx.from(users).insert({ email: "a@b.c" });
  // COMMIT on success, ROLLBACK on throw
});

Commit failures are classified into MountError("QUERY_FAILED") and a rollback is attempted (hardening audit #8).

Best for

Section titled “Best for”
  • Production server databases.
  • Multi-instance apps (sessions via PgTokenStore).
  • Anything needing real concurrency.

Best practices

Section titled “Best practices”
  • Set DATABASE_URL from env, not code.
  • Always release() a borrowed handle (use try/finally).
  • Use PgTokenStore for cross-instance sessions.

Common mistakes

Section titled “Common mistakes”
  • Assuming ? params (Postgres uses $N).
  • Forgetting to release() a borrowed client → pool exhaustion.
Section titled “Related”