findUnique() batching exceeding parameter binding limits

[chris-basis]

Bug description

While querying large datasets leveraging findUnique to prevent GraphQL N+1s, we're experiencing parameter binding errors due to the amount of bound parameters created in the batched query.

This causes the graphql query hitting these resolvers to fail.

Error:

prisma.account.findUnique(
  Assertion violation on the database: `too many bind variables in prepared statement, expected maximum of 32767, 
  received 150656`

How to reproduce

1. With over 33000 rows in the table you're querying
2. Perform 33000 individual entity.findUnique() queries in a Promise.all, simulating a large GQL N+1
3. Expect parameter binding error after surpassing your Postgres variable binding limit.

Expected behavior

Potentially split queries that would exceed the bound param limit into multiple batches.

Prisma information

Schema: Unrelated

Code:

    const accountIds = await prisma.account
        .findMany({
            select: { id: true },
            where: {
                companyId: redacted,
            },
        })
        .then((result) => result.map(({ id }) => id));

    await Promise.all(
        accountIds.map((id) =>
            prisma.account.findUnique({
                where: {
                    id,
                },
            })
        )
    );

Environment & setup

• OS: macOS, Windows, Debian, CentOS
• Database: PostgreSQL
• Node.js version: v20.11.1

Prisma Version

prisma                  : 5.7.1
@prisma/client          : 5.7.1
Computed binaryTarget   : darwin
Operating System        : darwin
Architecture            : x64
Node.js                 : v20.11.1
Query Engine (Node-API) : libquery-engine 0ca5ccbcfa6bdc81c003cf549abe4269f59c41e5 (at node_modules/@prisma/engines/libquery_engine-darwin.dylib.node)
Schema Engine           : schema-engine-cli 0ca5ccbcfa6bdc81c003cf549abe4269f59c41e5 (at node_modules/@prisma/engines/schema-engine-darwin)
Schema Wasm             : @prisma/prisma-schema-wasm 5.7.1-1.0ca5ccbcfa6bdc81c003cf549abe4269f59c41e5
Default Engines Hash    : 0ca5ccbcfa6bdc81c003cf549abe4269f59c41e5
Studio                  : 0.495.0
Preview Features        : metrics, relationJoins