Pull Request Checklist

• Have you added new tests to prevent regressions?
• If a documentation update is necessary, have you opened a PR to the documentation repository?
• Did you update the typescript typings accordingly (if applicable)?
• Does the description below contain a link to an existing issue or a description of the issue you are solving?
• Does the name of your PR follow our conventions?

Description of Changes

Stacked on #18329.

The bug

getTypeParser cached a parser under its OID alone:

const cachedParser = this.#oidParserCache.get(oid);

But pg asks for a parser per OID and wire format. Whichever format was requested first therefore won for both: once a text parser was cached for an OID, a later binary request for the same OID got that text parser back, and vice versa.

This matters because the dialect's parsers all take a string. Handing one to the binary protocol means it gets called with a Buffer.

The fix

Key the cache by format and OID, and only consult the dialect's custom parsers for the text format — letting pg's own parsers serve the binary format:

const cacheKey = `${format ?? 'text'}:${oid}`;
// ...
const customParser = format === 'binary' ? null : this.#getCustomTypeParser(oid);

#getCustomTypeParser now only ever runs for the text format, so it no longer takes a format parameter.

The same bug, from the other direction

The element parsers of arrays and ranges had the mirror-image problem: the requested format was forwarded to them, so a binary request built an array parser wrapped around pg's binary element parser — even though postgres-array only ever hands the element parser a string. They are text parsers now, which is the only thing they can be.

Tests

packages/postgres/src/connection-manager.test.ts covers the cache. The two format-crossover cases are genuine regression tests — verified failing against the parent branch and passing here:

1) does not hand out a text parser for the binary format
2) does not hand out a binary parser for the text format

40 postgres unit tests passing.

🤖 Generated with Claude Code

https://claude.ai/code/session_01EgPPfqYYk6PFGbanp5mAFh