Database type mappings

The inferred row type describes values returned by the typed-sql adapter under the selected typePolicy. Generation and runtime execution must use the same policy object.

PostgreSQL

PostgreSQL type	Default TypeScript type	Runtime value
smallint, integer	number	Finite JavaScript number
bigint	bigint	Native bigint
numeric, decimal	string	Exact decimal text
real, double precision	number	JavaScript number
boolean	boolean	JavaScript boolean
text, character, uuid	string	JavaScript string
date, timestamp, timestamptz	Date	JavaScript Date
json, jsonb	unknown	Parsed JSON value
bytea	Uint8Array	Node.js Buffer
enum	Literal string union	JavaScript string
supported T[]	readonly T[]	Recursively decoded array
nullable column	`T	null`

The PostgreSQL adapter installs parsers per query and does not mutate global pg.types. Policy-controlled OIDs use typed-sql codecs; other OIDs delegate to the installed driver parser table.

Policy alternatives:

Policy field	Values	Guarantee
bigint	bigint, string, number	number rejects values outside the safe integer range.
numeric	string, number, Decimal	number rejects non-finite values; Decimal requires a converter.
date	Date, string	string preserves driver text and database precision.
json	unknown, JsonValue, string	Object modes parse JSON; string preserves text.
enums	string-union, string	Both decode strings; only inference changes.

timestamp without time zone follows the Node.js process timezone when represented as Date. JavaScript dates lose PostgreSQL sub-millisecond precision. Choose string when those semantics are not acceptable.

MySQL

MySQL type	Default TypeScript type	Runtime value
tinyint(1), boolean, bool	boolean	Strict 0 or 1 conversion
other integer types	number	JavaScript number
bigint	bigint	Native bigint
decimal, numeric	string	Exact decimal text
float, double, real	number	JavaScript number
bit	Uint8Array	Node.js Buffer
character, text, time, set	string	JavaScript string
binary and blob types	Uint8Array	Node.js Buffer
date, datetime, timestamp	Date	Date converted from lossless text
year	number	JavaScript number
json	unknown	Parsed JSON value
enum	Literal string union	JavaScript string
nullable column	`T	null`

The adapter owns mysql2 settings that affect row shape and decoding. Supplying conflicting options through poolConfig fails before a pool is created.

Policy alternatives:

Policy field	Values	Guarantee
bigint	bigint, string, number	number rejects values outside the safe integer range.
decimal	string, number, Decimal	number may approximate fractions; Decimal requires a converter.
date	Date, string	Conversion occurs after mysql2 returns text.
json	unknown, JsonValue, string	Object modes use parsed JSON; string serializes it.
tinyint1	boolean, number	Conversion follows field type and length metadata.

Nullability, aggregates, and drift

Nullability is applied after scalar mapping. Outer joins add null to columns from the nullable relation. COUNT follows the dialect's bigint policy, while decimal-producing aggregates follow the numeric or decimal policy.

Generated snapshots include a typePolicyHash. typed-sql drift detects policy changes even when the database catalog remains unchanged.