Long queries with parameters

[eugene1g]

I have a custom query builder to help users run complex queries against the database using parameters to apply various filters. This query builder can generate really long queries, but not long enough to be a problem for PG. However, running those long queries with postgres doesn't work right now when those queries use parameters.

My real code is too complex to be useful, but here's a simple contrived example -

// test.mjs
import postgres from "postgres";

const sql = postgres({
  // The issue happens when two queries are executed sequentially over the same connection
  // It also happens with any number of connections, but easier to demo with a single network connection to schedule the queries predictably
  max: 1,
});

const padding = ".".repeat(16_342);

const res = await Promise.all([
  // For the bug to surface, the query needs to be 16,359 chars or longer
  // We'll create a "large" query to go first over the wire to PG
  // If we reduce the padding even by one character, everything works as expected (try removing the whitespace in the closing ` */`
  sql.unsafe(`SELECT 0+$1 /*${padding} */`, [1]),
  // Any following queries will fail when it runs over the same network connection
  sql.unsafe(`SELECT 0+$1+$2+$3`, [1, 2, 3]),
]);

console.log(res);
process.exit(0);

The specific error I get is -

PostgresError: bind message supplies 1 parameters, but prepared statement "" requires 2
    at ErrorResponse (..../postgres/cjs/src/connection.js:775:26)
    at handle (..../node_modules/postgres/cjs/src/connection.js:484:6)
    at Socket.data (..../node_modules/postgres/cjs/src/connection.js:328:9)
    at Socket.emit (node:events:527:28)
    at Socket.emit (node:domain:475:12)
    at addChunk (node:internal/streams/readable:324:12)
    at readableAddChunk (node:internal/streams/readable:297:9)
    at Socket.Readable.push (node:internal/streams/readable:234:10)
    at TCP.onStreamRead (node:internal/stream_base_commons:190:23)

It vaguely feels like the problem would be in the network serialization logic - perhaps some Buffer is overflowing or not being cleared - but I haven't narrowed this down further.

[eugene1g]

My example above is contrived, and for a more realistic example we can use a common pattern of running DB logic in parallel like so -

// test2.mjs
import postgres from "postgres";

const sql = postgres({
  // The issue happens when two queries are executed sequentially over the same connection
  // It also happens with any number of connections, but easier to demo with a single network connection to schedule the queries predictably
  max: 1,
});

const res = await Promise.all([
  // run IO-heavy functions in parallel
  fetchInfo(1), 
  calcSum(1, 2, 3),
]);

async function fetchInfo(someValue) {
  // Calling .unsafe will throw, calling sql`` will just hang
  // const padding = ".".repeat(16_342);
  // const info = await sql.unsafe(`SELECT 0+$1 /*${padding} */`, [someValue]);
  const info =
    await sql`SELECT 0+${1} /*......................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................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.........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................*/`;
  // do some post-processing of $info, then return it
  return info;
}

async function calcSum(val1, val2, val3) {
  // Calling .unsafe will throw, calling sql`` will just hang
  // const info = await sql.unsafe(`SELECT 0+$1+$2+$3`, [val1, val2, val3]);
  const info = await sql`SELECT 0+${val1}+${val2}+${val3}`;
  // do some post-processing of $info, then return it
  return info;
}

[porsager]

@eugene1g Very nice find, and a great description!

This is happening due to drain implicitly dequeueing the next query even if a query is currently in the describe phase (waiting for response). That results in describe being sent for the second query before sending the parameters for the first.

I'll push a fix ASAP!

[eugene1g]

Amazing

[porsager]

☺️ Thanks - now released in v3.0.4