MySQL snapshot support

Use this matrix before selecting mysqlSnapshotAdapter; it records the MySQL facts Qubu v1 can encode and the combinations that need a later server version or engine policy.

Import the adapter from the MySQL snapshot subpath:

import { createSchemaSnapshot, tryCreateSchemaSnapshot } from "qubu/snapshot/mysql"

const snapshot = createSchemaSnapshot(appSchema)
const result = tryCreateSchemaSnapshot(appSchema)

The snapshot dialect is named mysql, the same name used by Qubu's query renderer. A dialect-tagged unsafeSchemaSql('mysql', sql) expression belongs to this adapter.

Support matrix

Schema fact	MySQL v1 behavior
Portable storage	Maps integer to INT, numeric to DECIMAL, text to TEXT, boolean to BOOLEAN, date to DATE, timestamp to DATETIME, uuid to CHAR(36), json to JSON, bigint to BIGINT, and binary to VARBINARY.
Native storage	Preserves a non-empty declaration tagged mysql exactly. Native declarations owned by another dialect fail.
Literals	Encodes NULL, finite numbers, strings, booleans, and bigint without query parameters. Strings use SQL quote doubling.
Defaults	Canonical literals, branded deterministic expressions, and explicit external behavior are retained. Default expressions cannot reference columns or parameters.
ON UPDATE	A branded, parameter-free column expression is retained as onUpdate. PostgreSQL and SQLite adapters diagnose this MySQL-only fact.
AUTO_INCREMENT	identityColumn(..., { dialect: { dialect: 'mysql', autoIncrement: true } }) is retained as a column-level identity extension. The column must be non-nullable, integer-family storage, and the first term of a key.
Generated columns	Both stored and virtual modes are retained. Generated columns cannot also use ON UPDATE or AUTO_INCREMENT.
Keys and checks	Primary keys, strict unique keys, ordinary unique constraints, foreign keys, and checks retain logical and physical names, actions, and typed MySQL extension data.
Foreign keys	MATCH SIMPLE and standard actions except SET DEFAULT are supported. MATCH FULL, MATCH PARTIAL, deferrability, and SET DEFAULT are diagnosed.
Nullable uniqueness	nulls: 'distinct' is supported. nulls: 'not-distinct' is diagnosed because ordinary MySQL UNIQUE constraints allow multiple NULL values.
Indexes	Ordered terms, expressions, uniqueness, and candidate-key evidence are retained. Partial predicates, included columns, and NULLS FIRST/LAST are diagnosed. Algorithm, locking, access method, parser, and key-block options live under dialect.
Names	Table, column, constraint, and index names are checked against MySQL's 64-character identifier limit. Table names are database-scoped; index names are table-scoped.

Capability checks run before common traversal. Use the non-throwing form when a schema may include a MySQL engine or version-specific feature:

const result = tryCreateSchemaSnapshot(appSchema)
if (!result.ok) {
  for (const issue of result.diagnostics) {
    console.error(issue.path.join("."), issue.code, issue.message)
  }
}

The adapter does not connect to MySQL, inspect information_schema, or emit DDL. It produces deterministic data for the strict qubu/snapshot decoder. The package-wide ownership map shows the separate schema and application boundaries.