Support for pipelining

[stephenh]

Is your feature request related to a problem? Please describe.

Pipelining allows a txn to send all of its INSERTs/UPDATEs/DELETEs "simultaneously" without waiting for responses to each one. This can lead to ~3-6x perf increases, depending on the data/benchmark:

https://joist-orm.io/blog/initial-pipelining-benchmark/

Describe the solution you'd like

A way to have multiple queries issued, and then awaitd via Promise.all, like:

bench("pipeline Promise.all", async () => {
  await sql.begin(async (sql) => {
    const statements = [];
    for (let i = 0; i < numStatements; i++) {
      statements.push(sql`INSERT INTO tag (name) VALUES (${`value-${nextTag++}`})`);
    }
    await Promise.all(statements);
  });
});

(This uses the postgres.js syntax, which fwiw I'm not actually a huge fan of/tied to, but it does technically allow submitted multiple statements like this pretty easy.)

Describe alternatives you've considered

No alternatives, other than just not using pipelining.

Additional context

[erayhanoglu]

Yes this is a good feature. We will plan to implement this.