> For the complete documentation index, see [llms.txt](https://docs.prestd.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.prestd.com/releases/v2.5.1.md).

# v2.5.1

pREST v2.5.1 fixes MySQL bugs from v2.5.0: MCP, alias schema scope, exact large integers, and 503 responses that hide driver text.

Released: October 8, 2026

[GitHub tag](https://github.com/prest/prest/releases/tag/v2.5.1) · [Compare v2.5.0...v2.5.1](https://github.com/prest/prest/compare/v2.5.0...v2.5.1)

**v2.5.1** fixes MySQL behavior that shipped broken or incomplete in [v2.5.0](/releases/v2.5.0.md). One change: [#1056](https://github.com/prest/prest/pull/1056). It is a fix on that tag, not a new engine. Anyone who installed v2.5.0 for MySQL should move to v2.5.1. No new config key.

* **Docker:** `prest/prest:v2.5.1` (linux/amd64 and linux/arm64)
* **Go install:** `go install github.com/prest/prest/v2/cmd/prestd@v2.5.1`

***

## Highlights

### Registry and engine selection ([#1056](https://github.com/prest/prest/pull/1056))

A `[[databases]]` alias serves only the database named in its `url` or `database`. Any other `{schema}` is **404** on CRUD, `/show`, and `/{alias}/{schema}` table listing. One MySQL login can otherwise see every granted database, so this stops cross-database reads through the path.

In registry mode `/databases` returns `[{"datname": alias, "name": alias, "physical_name": database}]` instead of every database on the server.

With no `[[databases]]` block, the single connection still serves every granted database as `{schema}`.

Exception to “URLs are not sniffed”: a `[[databases]]` entry whose `url` starts with `mysql://` and has **no** `engine` is MySQL. Any other URL is not probed. Empty root `engine` stays PostgreSQL, including Timescale detection.

### Types, batch, errors, auth ([#1056](https://github.com/prest/prest/pull/1056))

Request bodies use `UseNumber`. Integers above 2^53 (example `9007199254740993`) are written exactly. This applies to MySQL and PostgreSQL.

MySQL JSON scan: integers, including `BIGINT UNSIGNED`, are JSON numbers with `interpolateParams` and with `prepare`. `DECIMAL` / `NUMERIC` stay strings, so `SUM` / `AVG` of an integer column is a string. An aggregate without an alias uses the Postgres key (`sum`, `avg`, `count`, `min`, `max`).

`BLOB` / `BINARY` / `VARBINARY` / `BIT` / `GEOMETRY` render as Postgres bytea `"\\x` plus lowercase hex, in REST and MCP. A `\x…` string written into a binary column is stored as those characters, not decoded.

`DATE` is `YYYY-MM-DD`. `DATETIME` has no zone (`2006-01-02T15:04:05.999999`) so it can be written back. `TIMESTAMP` is UTC with `+00:00`.

`_count` is `` COUNT(...) AS `count` `` so the response key matches Postgres.

Batch insert uses the union of keys. A missing key is SQL `DEFAULT` on MySQL and on PostgreSQL insert. PostgreSQL `COPY` still returns **400** when records differ, because `COPY` has no `DEFAULT`. `Prest-Batch-Method: copy` on MySQL remains a transactional multi-row `INSERT`, not `LOAD DATA`.

JSON objects and slices are bound as JSON text (utf8mb4), not `[]byte`, so `interpolateParams=true` does not send a `_binary` literal (MySQL error 3144). No per-alias `prepare` key is required.

Value-less operators (`$null`, `$notnull`, `$true`, `$nottrue`, `$false`, `$notfalse`) work with or without a trailing dot.

Numeric comparison of a non-number (`?n=$gt.abc`) follows MySQL: it compares with `0` and can match rows. Postgres still errors.

Connection failure (down, refused, timed out) is **503** `{"error":"database unavailable"}` with no driver text. MySQL 1146, 1142, 1044, and 1049 are **404**. For 1142, 1044, and 1049 the server text is dropped because it names the account (`'prest'@'host'`).

`/auth` on MySQL uses backticks and `?`. Unset `auth.schema` defaults to the connection database, because `public` does not exist.

### MCP on MySQL ([#1056](https://github.com/prest/prest/pull/1056))

Supported from v2.5.1. `select_table` quotes with backticks and binds filters as `?`. In a mixed registry each alias uses its own catalog, executor, and dialect. Read-only rules from the [MCP over HTTP](/get-started/mcp-over-http.md) guide still apply. MariaDB is still out of scope.

### Images and plugins ([#1056](https://github.com/prest/prest/pull/1056))

Docker tags are multi-arch **linux/amd64** and **linux/arm64**. The image binary is a separate GoReleaser build (`prestd-docker`) with `CGO_ENABLED=1`, `-mod=vendor`, and `-trimpath`, so `plugin.Open` still accepts `.so` files built the same way as [Middleware Plugin](/plugins/middleware-plugin.md). Release archives stay the portable (non-cgo) build.

***

## Changes since v2.5.0

| PR                                                | Summary                                                                                       |
| ------------------------------------------------- | --------------------------------------------------------------------------------------------- |
| [#1056](https://github.com/prest/prest/pull/1056) | MySQL v2.5.0 bugfix: MCP, registry scope, types, batch `DEFAULT`, and 503 without driver text |

Full detail: [compare v2.5.0...v2.5.1](https://github.com/prest/prest/compare/v2.5.0...v2.5.1). Commit list: [Changes since v2.5.0](/releases/main-since-v2.5.0.md).

***

## Upgrading from v2.5.0

1. Retag to `prest/prest:v2.5.1` or `go install github.com/prest/prest/v2/cmd/prestd@v2.5.1`. No new setting.
2. If you use `[[databases]]` with MySQL, expect `{schema}` to be only that alias’s database. A path that used another schema on the same login now 404s.
3. If you skipped [v2.4.2](/releases/v2.4.2.md), the HMAC `jwt.key` warning still applies. A short key does not stop startup — it disables `/auth`. See [v2.4.2 — Upgrading](/releases/v2.4.2.md#upgrading-from-v241).

***

## Related

* [MySQL](/databases/mysql.md)
* [Databases](/databases.md)
* [MCP over HTTP](/get-started/mcp-over-http.md)
* [v2.5.0 release notes](/releases/v2.5.0.md)
* [Middleware Plugin](/plugins/middleware-plugin.md)
* [Acronyms](/readme/acronyms.md) ([MCP](/readme/acronyms.md#mcp), [REST](/readme/acronyms.md#rest), [JWT](/readme/acronyms.md#jwt))


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