Bug description

The inferCapabilities function in @prisma/adapter-mariadb has a broken semver comparison that causes supportsRelationJoins to incorrectly evaluate to false for MySQL versions >= 8.1.0 where the patch version is less than 13.

This forces Prisma to fall back to multi-query relation loading (separate SQL statements wrapped in BEGIN/COMMIT) instead of using lateral JOINs, resulting in unnecessary performance overhead.

Location

@prisma/adapter-mariadb/dist/index.mjs — inferCapabilities():

function inferCapabilities(version) {
  if (typeof version !== "string") {
    return { supportsRelationJoins: false };
  }
  const [versionStr, suffix] = version.split("-");
  const [major, minor, patch] = versionStr.split(".").map((n) => parseInt(n, 10));
  const isMariaDB = suffix?.toLowerCase()?.includes("mariadb") ?? false;
  const supportsRelationJoins = !isMariaDB && (major > 8 || major === 8 && minor >= 0 && patch >= 13);
  return { supportsRelationJoins };
}

The condition major === 8 && minor >= 0 && patch >= 13 checks the patch version independently of the minor version. This means any MySQL 8.x.y version where y < 13 fails the check, even if x > 0 (which implies a version newer than 8.0.13).

Examples

All MySQL versions from 8.1.0 through 8.x.12 (where x >= 1) are incorrectly treated as not supporting relation JOINs. This covers the current MySQL 8.4 LTS and Innovation releases 8.1, 8.2, and 8.3.

Suggested fix

Replace the flat && comparison with a proper semver-aware check:

const supportsRelationJoins = !isMariaDB && (
  major > 8 ||
  (major === 8 && (minor > 0 || (minor === 0 && patch >= 13)))
);

This correctly treats any MySQL 8.1+ as newer than 8.0.13.

Impact

When supportsRelationJoins is incorrectly false, Prisma:

1. Falls back to separate SQL queries for relation loading instead of using lateral JOINs
2. Wraps those multi-query operations in implicit transactions (BEGIN / SELECT / SELECT / COMMIT), adding 3+ round-trips per query instead of 1
3. Effectively prevents parallel execution of concurrent Prisma queries (via Promise.all) because each query's implicit transaction occupies a connection for longer and adds synchronous overhead between queries

Environment

• @prisma/adapter-mariadb: 7.4.1 (also verified in 7.5.0)
• MySQL: 8.1.0, 8.4.0 (affected)
• MySQL: 8.0.32 (not affected)