diff --git a/mod.ts b/mod.ts
index a6ebf31..c21392f 100644
--- a/mod.ts
+++ b/mod.ts
@@ -9,7 +9,7 @@ import {
   unknown,
 } from "./valita.ts";
 import { Pool, wire_connect, type LogLevel } from "./wire.ts";
-import { type FromSql, type ToSql, from_sql, to_sql } from "./sql.ts";
+import { sql_types, type SqlType, type SqlTypeMap } from "./query.ts";
 
 export {
   WireError,
@@ -21,13 +21,11 @@ export {
 } from "./wire.ts";
 export {
   type SqlFragment,
-  type FromSql,
-  type ToSql,
-  SqlValue,
+  type SqlType,
+  type SqlTypeMap,
+  SqlTypeError,
   sql,
   is_sql,
-} from "./sql.ts";
-export {
   Query,
   type Row,
   type CommandResult,
@@ -45,8 +43,7 @@ export type Options = {
   max_connections?: number;
   idle_timeout?: number;
   runtime_params?: Record<string, string>;
-  from_sql?: FromSql;
-  to_sql?: ToSql;
+  types?: SqlTypeMap;
 };
 
 type ParsedOptions = Infer<typeof ParsedOptions>;
@@ -64,15 +61,12 @@ const ParsedOptions = object({
   runtime_params: record(string()).optional(() => ({})),
   max_connections: number().optional(() => 10),
   idle_timeout: number().optional(() => 20),
-  from_sql: unknown()
-    .assert((s): s is FromSql => typeof s === "function")
-    .optional(() => from_sql),
-  to_sql: unknown()
-    .assert((s): s is ToSql => typeof s === "function")
-    .optional(() => to_sql),
+  types: record(unknown())
+    .optional(() => ({}))
+    .map((types): SqlTypeMap => ({ ...sql_types, ...types })),
 });
 
-function parse_opts(s: string, options: Options) {
+function parse_opts(s: string, opts: Options) {
   const {
     host,
     port,
@@ -87,13 +81,13 @@ function parse_opts(s: string, options: Options) {
     Deno.env.toObject();
 
   return ParsedOptions.parse({
-    ...options,
-    host: options.host ?? host ?? PGHOST ?? undefined,
-    port: options.port ?? port ?? PGPORT ?? undefined,
-    user: options.user ?? user ?? PGUSER ?? USER ?? undefined,
-    password: options.password ?? password ?? PGPASSWORD ?? undefined,
-    database: options.database ?? database ?? PGDATABASE ?? undefined,
-    runtime_params: { ...runtime_params, ...options.runtime_params },
+    ...opts,
+    host: opts.host ?? host ?? PGHOST ?? undefined,
+    port: opts.port ?? port ?? PGPORT ?? undefined,
+    user: opts.user ?? user ?? PGUSER ?? USER ?? undefined,
+    password: opts.password ?? password ?? PGPASSWORD ?? undefined,
+    database: opts.database ?? database ?? PGDATABASE ?? undefined,
+    runtime_params: { ...runtime_params, ...opts.runtime_params },
   });
 }
 
diff --git a/mod_test.ts b/mod_test.ts
index fbecb5f..f55213e 100644
--- a/mod_test.ts
+++ b/mod_test.ts
@@ -6,8 +6,18 @@ await using pool = postgres(`postgres://test:test@localhost:5432/test`, {
 
 pool.on("log", (level, ctx, msg) => console.info(`${level}: ${msg}`, ctx));
 
-await pool.begin(async (pg) => {
-  await pg.begin(async (pg) => {
-    console.log(await pg.query`select * from pg_user`);
-  });
+await pool.begin(async (pg, tx) => {
+  await pg.query`
+    create table my_test (
+      key integer primary key generated always as identity,
+      data text not null
+    )
+  `;
+
+  await pg.query`
+    insert into my_test (data) values (${[1, 2, 3]}::bytea)
+  `;
+
+  console.log(await pg.query`select * from my_test`);
+  await tx.rollback();
 });
diff --git a/query.ts b/query.ts
index 9596447..1c7956b 100644
--- a/query.ts
+++ b/query.ts
@@ -1,62 +1,302 @@
 import type { ObjectType } from "./valita.ts";
-import { from_utf8, jit, to_utf8 } from "./lstd.ts";
-import { type FromSql, SqlValue } from "./sql.ts";
+import { from_hex, to_hex, to_utf8 } from "./lstd.ts";
 
-export interface Row extends Iterable<unknown, void, void> {
-  [column: string]: unknown;
+export const sql_format = Symbol.for(`re.lua.pglue.sql_format`);
+
+export interface SqlFragment {
+  [sql_format](f: SqlFormatter): void;
 }
 
-export interface RowConstructor {
-  new (columns: (Uint8Array | string | null)[]): Row;
+export interface SqlFormatter {
+  query: string;
+  params: unknown[];
 }
 
-export interface RowDescription extends ReadonlyArray<ColumnDescription> {}
-
-export interface ColumnDescription {
-  readonly name: string;
-  readonly table_oid: number;
-  readonly table_column: number;
-  readonly type_oid: number;
-  readonly type_size: number;
-  readonly type_modifier: number;
+export function is_sql(x: unknown): x is SqlFragment {
+  return typeof x === "object" && x !== null && sql_format in x;
 }
 
-export function row_ctor(from_sql: FromSql, columns: RowDescription) {
-  function parse(s: Uint8Array | string | null | undefined) {
-    if (!s && s !== "") return null;
-    else return from_utf8(s);
+export function sql(
+  { raw: s }: TemplateStringsArray,
+  ...xs: unknown[]
+): SqlFragment {
+  return {
+    [sql_format](fmt) {
+      for (let i = 0, n = s.length; i < n; i++) {
+        if (i !== 0) fmt_format(fmt, xs[i - 1]);
+        fmt.query += s[i];
+      }
+    },
+  };
+}
+
+export function fmt_write(fmt: SqlFormatter, s: string | SqlFragment) {
+  is_sql(s) ? s[sql_format](fmt) : (fmt.query += s);
+}
+
+export function fmt_format(fmt: SqlFormatter, x: unknown) {
+  is_sql(x) ? x[sql_format](fmt) : fmt_enclose(fmt, x);
+}
+
+export function fmt_enclose(fmt: SqlFormatter, x: unknown) {
+  const { params } = fmt;
+  params.push(x), (fmt.query += `$` + params.length);
+}
+
+sql.format = format;
+sql.raw = raw;
+sql.ident = ident;
+sql.fragment = fragment;
+sql.map = map;
+sql.array = array;
+sql.row = row;
+
+export function format(sql: SqlFragment) {
+  const fmt: SqlFormatter = { query: "", params: [] };
+  return sql[sql_format](fmt), fmt;
+}
+
+export function raw(s: string): SqlFragment;
+export function raw(s: TemplateStringsArray, ...xs: unknown[]): SqlFragment;
+export function raw(
+  s: TemplateStringsArray | string,
+  ...xs: unknown[]
+): SqlFragment {
+  s = typeof s === "string" ? s : String.raw(s, ...xs);
+  return {
+    [sql_format](fmt) {
+      fmt.query += s;
+    },
+  };
+}
+
+export function ident(s: string): SqlFragment;
+export function ident(s: TemplateStringsArray, ...xs: unknown[]): SqlFragment;
+export function ident(s: TemplateStringsArray | string, ...xs: unknown[]) {
+  s = typeof s === "string" ? s : String.raw(s, ...xs);
+  return raw`"${s.replaceAll('"', '""')}"`;
+}
+
+export function fragment(
+  sep: string | SqlFragment,
+  ...xs: unknown[]
+): SqlFragment {
+  return {
+    [sql_format](fmt) {
+      for (let i = 0, n = xs.length; i < n; i++) {
+        if (i !== 0) fmt_write(fmt, sep);
+        fmt_format(fmt, xs[i]);
+      }
+    },
+  };
+}
+
+export function map<T>(
+  sep: string | SqlFragment,
+  xs: Iterable<T>,
+  f: (value: T, index: number) => unknown
+) {
+  return fragment(sep, ...Iterator.from(xs).map(f));
+}
+
+export function array(...xs: unknown[]) {
+  return sql`array[${fragment(", ", ...xs)}]`;
+}
+
+export function row(...xs: unknown[]) {
+  return sql`row(${fragment(", ", ...xs)})`;
+}
+
+export interface SqlType {
+  input(value: string): unknown;
+  output(value: unknown): string | null;
+}
+
+export interface SqlTypeMap {
+  readonly [oid: number]: SqlType | undefined;
+}
+
+export class SqlTypeError extends TypeError {
+  override get name() {
+    return this.constructor.name;
   }
-
-  const Row = jit.compiled<RowConstructor>`function Row(xs) {
-    ${jit.map(" ", columns, ({ name, type_oid }, i) => {
-      return jit`this[${name}] = ${from_sql}(new ${SqlValue}(${type_oid}, ${parse}(xs[${i}])));`;
-    })}
-  }`;
-
-  Row.prototype = Object.create(null, {
-    [Symbol.toStringTag]: {
-      configurable: true,
-      value: `Row`,
-    },
-    [Symbol.toPrimitive]: {
-      configurable: true,
-      value: function format() {
-        return [...this].join("\t");
-      },
-    },
-    [Symbol.iterator]: {
-      configurable: true,
-      value: jit.compiled`function* iter() {
-        ${jit.map(" ", columns, ({ name }) => {
-          return jit`yield this[${name}];`;
-        })}
-      }`,
-    },
-  });
-
-  return Row;
 }
 
+export const bool: SqlType = {
+  input(s) {
+    return s !== "f";
+  },
+  output(x) {
+    return typeof x === "undefined" || x === null ? null : x ? "t" : "f";
+  },
+};
+
+export const text: SqlType = {
+  input(s) {
+    return s;
+  },
+  output(x) {
+    if (typeof x === "undefined" || x === null) return null;
+    else if (typeof x === "string") return x;
+    else return String(x);
+  },
+};
+
+export const int2: SqlType = {
+  input(s) {
+    const n = Number(s);
+    if (Number.isInteger(n) && -32768 <= n && n <= 32767) return n;
+    else throw new SqlTypeError(`invalid int2 input '${s}'`);
+  },
+  output(x) {
+    let n: number;
+    if (typeof x === "undefined" || x === null) return null;
+    else if (typeof x === "number") n = x;
+    else n = Number(x);
+    if (Number.isInteger(n) && -32768 <= n && n <= 32767) return n.toString();
+    else throw new SqlTypeError(`invalid int2 output '${x}'`);
+  },
+};
+
+export const int4: SqlType = {
+  input(s) {
+    const n = Number(s);
+    if (Number.isInteger(n) && -2147483648 <= n && n <= 2147483647) return n;
+    else throw new SqlTypeError(`invalid int4 input '${s}'`);
+  },
+  output(x) {
+    let n: number;
+    if (typeof x === "undefined" || x === null) return null;
+    else if (typeof x === "number") n = x;
+    else n = Number(x);
+    if (Number.isInteger(n) && -2147483648 <= n && n <= 2147483647)
+      return n.toString();
+    else throw new SqlTypeError(`invalid int4 output '${x}'`);
+  },
+};
+
+export const int8: SqlType = {
+  input(s) {
+    const n = BigInt(s);
+    if (-9007199254740991n <= n && n <= 9007199254740991n) return Number(n);
+    else if (-9223372036854775808n <= n && n <= 9223372036854775807n) return n;
+    else throw new SqlTypeError(`invalid int8 input '${s}'`);
+  },
+  output(x) {
+    let n: number | bigint;
+    if (typeof x === "undefined" || x === null) return null;
+    else if (typeof x === "number" || typeof x === "bigint") n = x;
+    else if (typeof x === "string") n = BigInt(x);
+    else n = Number(x);
+    if (Number.isInteger(n)) {
+      if (-9007199254740991 <= n && n <= 9007199254740991) return n.toString();
+      else throw new SqlTypeError(`unsafe int8 output '${x}'`);
+    } else if (typeof n === "bigint") {
+      if (-9223372036854775808n <= n && n <= 9223372036854775807n)
+        return n.toString();
+    }
+    throw new SqlTypeError(`invalid int8 output '${x}'`);
+  },
+};
+
+export const float4: SqlType = {
+  input(s) {
+    return Math.fround(Number(s));
+  },
+  output(x) {
+    let n: number;
+    if (typeof x === "undefined" || x === null) return null;
+    else if (typeof x === "number") n = x;
+    else {
+      n = Number(x);
+      if (Number.isNaN(n))
+        throw new SqlTypeError(`invalid float4 output '${x}'`);
+    }
+    return Math.fround(n).toString();
+  },
+};
+
+export const float8: SqlType = {
+  input(s) {
+    return Number(s);
+  },
+  output(x) {
+    let n: number;
+    if (typeof x === "undefined" || x === null) return null;
+    else if (typeof x === "number") n = x;
+    else {
+      n = Number(x);
+      if (Number.isNaN(n))
+        throw new SqlTypeError(`invalid float8 output '${x}'`);
+    }
+    return n.toString();
+  },
+};
+
+export const timestamptz: SqlType = {
+  input(s) {
+    const t = Date.parse(s);
+    if (!Number.isNaN(t)) return new Date(t);
+    else throw new SqlTypeError(`invalid timestamptz input '${s}'`);
+  },
+  output(x) {
+    let t: Date;
+    if (typeof x === "undefined" || x === null) return null;
+    else if (x instanceof Date) t = x;
+    else if (typeof x === "number" || typeof x === "bigint")
+      t = new Date(Number(x) * 1000); // unix epoch seconds
+    else t = new Date(String(x));
+    if (Number.isFinite(t.getTime())) return t.toISOString();
+    else throw new SqlTypeError(`invalid timestamptz output '${x}'`);
+  },
+};
+
+export const bytea: SqlType = {
+  input(s) {
+    if (s.startsWith(`\\x`)) return from_hex(s.slice(2));
+    else throw new SqlTypeError(`invalid bytea input '${s}'`);
+  },
+  output(x) {
+    let buf: Uint8Array;
+    if (typeof x === "undefined" || x === null) return null;
+    else if (typeof x === "string") buf = to_utf8(x);
+    else if (x instanceof Uint8Array) buf = x;
+    else if (x instanceof ArrayBuffer || x instanceof SharedArrayBuffer)
+      buf = new Uint8Array(x);
+    else if (Array.isArray(x) || x instanceof Array) buf = Uint8Array.from(x);
+    else throw new SqlTypeError(`invalid bytea output '${x}'`);
+    return `\\x` + to_hex(buf);
+  },
+};
+
+export const json: SqlType = {
+  input(s) {
+    return JSON.parse(s);
+  },
+  output(x) {
+    return typeof x === "undefined" ? null : JSON.stringify(x);
+  },
+};
+
+export const sql_types: SqlTypeMap = {
+  16: bool, // bool
+  25: text, // text
+  21: int2, // int2
+  23: int4, // int4
+  20: int8, // int8
+  26: int8, // oid
+  700: float4, // float4
+  701: float8, // float8
+  1082: timestamptz, // date
+  1114: timestamptz, // timestamp
+  1184: timestamptz, // timestamptz
+  17: bytea, // bytea
+  114: json, // json
+  3802: json, // jsonb
+};
+
+sql.types = sql_types;
+
 type ReadonlyTuple<T extends readonly unknown[]> = readonly [...T];
 
 export interface CommandResult {
@@ -74,6 +314,10 @@ export interface Results<T> extends CommandResult, ReadonlyArray<T> {
 export interface ResultStream<T>
   extends AsyncIterable<T[], CommandResult, void> {}
 
+export interface Row extends Iterable<unknown, void, void> {
+  [column: string]: unknown;
+}
+
 export interface QueryOptions {
   readonly chunk_size: number;
   readonly stdin: ReadableStream<Uint8Array> | null;
diff --git a/sql.ts b/sql.ts
deleted file mode 100644
index 9d7bdc9..0000000
--- a/sql.ts
+++ /dev/null
@@ -1,386 +0,0 @@
-import { from_hex, to_hex } from "./lstd.ts";
-
-export const sql_format = Symbol.for(`re.lua.pglue.sql_format`);
-
-export interface SqlFragment {
-  [sql_format](f: SqlFormatter): void;
-}
-
-export function is_sql(x: unknown): x is SqlFragment {
-  return typeof x === "object" && x !== null && sql_format in x;
-}
-
-export interface FromSql {
-  (x: SqlValue): unknown;
-}
-
-export interface ToSql {
-  (x: unknown): SqlFragment;
-}
-
-export const from_sql = function from_sql(x) {
-  const { type, value } = x;
-  if (value === null) return null;
-
-  switch (type) {
-    case 16: // boolean
-      return boolean.parse(value);
-    case 25: // text
-      return text.parse(value);
-    case 21: // int2
-      return int2.parse(value);
-    case 23: // int4
-      return int4.parse(value);
-    case 20: // int8
-    case 26: // oid
-      return int8.parse(value);
-    case 700: // float4
-      return float4.parse(value);
-    case 701: // float8
-      return float8.parse(value);
-    case 1082: // date
-    case 1114: // timestamp
-    case 1184: // timestamptz
-      return timestamptz.parse(value);
-    case 17: // bytea
-      return bytea.parse(value);
-    case 114: // json
-    case 3802: // jsonb
-      return json.parse(value);
-    default:
-      return x;
-  }
-} as FromSql;
-
-export const to_sql = function to_sql(x) {
-  switch (typeof x) {
-    case "undefined":
-      return nil();
-    case "boolean":
-      return boolean(x);
-    case "number":
-      return float8(x);
-    case "bigint":
-      return int8(x);
-    case "string":
-    case "symbol":
-    case "function":
-      return text(x);
-  }
-
-  switch (true) {
-    case x === null:
-      return nil();
-
-    case is_sql(x):
-      return x;
-
-    case Array.isArray(x):
-      return array(...(x instanceof Array ? x : Array.from(x)));
-
-    case x instanceof Date:
-      return timestamptz(x);
-
-    case x instanceof Uint8Array:
-    case x instanceof ArrayBuffer:
-    case x instanceof SharedArrayBuffer:
-      return bytea(x);
-  }
-
-  throw new TypeError(`cannot convert input '${x}' to sql`);
-} as ToSql;
-
-export class SqlValue implements SqlFragment {
-  constructor(
-    readonly type: number,
-    readonly value: string | null
-  ) {}
-
-  [sql_format](f: SqlFormatter) {
-    f.write_param(this.type, this.value);
-  }
-
-  [Symbol.toStringTag]() {
-    return `${this.constructor.name}<${this.type}>`;
-  }
-
-  [Symbol.toPrimitive]() {
-    return this.value;
-  }
-
-  toString() {
-    return String(this.value);
-  }
-
-  toJSON() {
-    return this.value;
-  }
-}
-
-export function value(type: number, x: unknown) {
-  const s = x === null || typeof x === "undefined" ? null : String(x);
-  return new SqlValue(type, s);
-}
-
-export class SqlFormatter {
-  readonly #ser;
-  #query = "";
-  #params = {
-    types: [] as number[],
-    values: [] as (string | null)[],
-  };
-
-  get query() {
-    return this.#query.trim();
-  }
-
-  get params() {
-    return this.#params;
-  }
-
-  constructor(serializer: ToSql) {
-    this.#ser = serializer;
-  }
-
-  write(s: string | SqlFragment) {
-    if (is_sql(s)) s[sql_format](this);
-    else this.#query += s;
-  }
-
-  write_param(type: number, s: string | null) {
-    const { types, values } = this.#params;
-    types.push(type), values.push(s), this.write(`$` + values.length);
-  }
-
-  format(x: unknown) {
-    this.write(is_sql(x) ? x : this.#ser(x));
-  }
-}
-
-export function format(sql: SqlFragment, serializer = to_sql) {
-  const fmt = new SqlFormatter(serializer);
-  return fmt.write(sql), fmt;
-}
-
-export function sql(
-  { raw: s }: TemplateStringsArray,
-  ...xs: unknown[]
-): SqlFragment {
-  return {
-    [sql_format](f) {
-      for (let i = 0, n = s.length; i < n; i++) {
-        if (i !== 0) f.format(xs[i - 1]);
-        f.write(s[i]);
-      }
-    },
-  };
-}
-
-sql.value = value;
-sql.format = format;
-sql.raw = raw;
-sql.ident = ident;
-sql.fragment = fragment;
-sql.map = map;
-sql.array = array;
-sql.row = row;
-sql.null = nil;
-sql.boolean = boolean;
-sql.text = text;
-sql.int2 = int2;
-sql.int4 = int4;
-sql.int8 = int8;
-sql.float4 = float4;
-sql.float8 = float8;
-sql.timestamptz = timestamptz;
-sql.bytea = bytea;
-sql.json = json;
-
-export function raw(s: TemplateStringsArray, ...xs: unknown[]): SqlFragment;
-export function raw(s: string): SqlFragment;
-export function raw(
-  s: TemplateStringsArray | string,
-  ...xs: unknown[]
-): SqlFragment {
-  s = typeof s === "string" ? s : String.raw(s, ...xs);
-  return {
-    [sql_format](f) {
-      f.write(s);
-    },
-  };
-}
-
-export function ident(s: TemplateStringsArray, ...xs: unknown[]): SqlFragment;
-export function ident(s: string): SqlFragment;
-export function ident(s: TemplateStringsArray | string, ...xs: unknown[]) {
-  s = typeof s === "string" ? s : String.raw(s, ...xs);
-  return raw`"${s.replaceAll('"', '""')}"`;
-}
-
-export function fragment(
-  sep: string | SqlFragment,
-  ...xs: unknown[]
-): SqlFragment {
-  return {
-    [sql_format](f) {
-      for (let i = 0, n = xs.length; i < n; i++) {
-        if (i !== 0) f.write(sep);
-        f.format(xs[i]);
-      }
-    },
-  };
-}
-
-export function map<T>(
-  sep: string | SqlFragment,
-  xs: Iterable<T>,
-  f: (value: T, index: number) => unknown
-): SqlFragment {
-  return fragment(sep, ...Iterator.from(xs).map(f));
-}
-
-export function array(...xs: unknown[]): SqlFragment {
-  return sql`array[${fragment(", ", ...xs)}]`;
-}
-
-export function row(...xs: unknown[]): SqlFragment {
-  return sql`row(${fragment(", ", ...xs)})`;
-}
-
-boolean.oid = 16 as const;
-text.oid = 25 as const;
-int2.oid = 21 as const;
-int4.oid = 23 as const;
-int8.oid = 20 as const;
-float4.oid = 700 as const;
-float8.oid = 701 as const;
-timestamptz.oid = 1184 as const;
-bytea.oid = 17 as const;
-json.oid = 114 as const;
-
-export function nil() {
-  return value(0, null);
-}
-
-Object.defineProperty(nil, "name", { configurable: true, value: "null" });
-
-export function boolean(x: unknown) {
-  return value(
-    boolean.oid,
-    x === null || typeof x === "undefined" ? null : x ? "t" : "f"
-  );
-}
-
-boolean.parse = function parse_boolean(s: string) {
-  return s === "t";
-};
-
-export function text(x: unknown) {
-  return value(text.oid, x);
-}
-
-text.parse = function parse_text(s: string) {
-  return s;
-};
-
-const i2_min = -32768;
-const i2_max = 32767;
-
-export function int2(x: unknown) {
-  return value(int2.oid, x);
-}
-
-int2.parse = function parse_int2(s: string) {
-  const n = Number(s);
-  if (Number.isInteger(n) && i2_min <= n && n <= i2_max) return n;
-  else throw new TypeError(`input '${s}' is not a valid int2 value`);
-};
-
-const i4_min = -2147483648;
-const i4_max = 2147483647;
-
-export function int4(x: unknown) {
-  return value(int4.oid, x);
-}
-
-int4.parse = function parse_int4(s: string) {
-  const n = Number(s);
-  if (Number.isInteger(n) && i4_min <= n && n <= i4_max) return n;
-  else throw new TypeError(`input '${s}' is not a valid int4 value`);
-};
-
-const i8_min = -9223372036854775808n;
-const i8_max = 9223372036854775807n;
-
-export function int8(x: unknown) {
-  return value(int8.oid, x);
-}
-
-function to_int8(n: number | bigint) {
-  if (typeof n === "bigint") return i8_min <= n && n <= i8_max ? n : null;
-  else return Number.isSafeInteger(n) ? BigInt(n) : null;
-}
-
-int8.parse = function parse_int8(s: string) {
-  const n = to_int8(BigInt(s));
-  if (n !== null) return to_float8(n) ?? n;
-  else throw new TypeError(`input '${s}' is not a valid int8 value`);
-};
-
-const f8_min = -9007199254740991n;
-const f8_max = 9007199254740991n;
-
-export function float4(x: unknown) {
-  return value(float4.oid, x);
-}
-
-export function float8(x: unknown) {
-  return value(float8.oid, x);
-}
-
-function to_float8(n: number | bigint) {
-  if (typeof n === "bigint")
-    return f8_min <= n && n <= f8_max ? Number(n) : null;
-  else return Number.isNaN(n) ? null : n;
-}
-
-float4.parse = float8.parse = function parse_float8(s: string) {
-  const n = to_float8(Number(s));
-  if (n !== null) return n;
-  else throw new TypeError(`input '${s}' is not a valid float8 value`);
-};
-
-export function timestamptz(x: unknown) {
-  if (x instanceof Date) x = x.toISOString();
-  else if (typeof x === "number" || typeof x === "bigint")
-    x = new Date(Number(x) * 1000).toISOString(); // unix epoch
-  return value(timestamptz.oid, x);
-}
-
-timestamptz.parse = function parse_timestamptz(s: string) {
-  const t = Date.parse(s);
-  if (!Number.isNaN(t)) return new Date(t);
-  else throw new TypeError(`input '${s}' is not a valid timestamptz value`);
-};
-
-export function bytea(x: Uint8Array | ArrayBufferLike | Iterable<number>) {
-  let buf;
-  if (x instanceof Uint8Array) buf = x;
-  else if (x instanceof ArrayBuffer || x instanceof SharedArrayBuffer)
-    buf = new Uint8Array(x);
-  else buf = Uint8Array.from(x);
-  return value(bytea.oid, `\\x` + to_hex(buf));
-}
-
-bytea.parse = function parse_bytea(s: string) {
-  if (s.startsWith(`\\x`)) return from_hex(s.slice(2));
-  else throw new TypeError(`input is not a valid bytea value`);
-};
-
-export function json(x: unknown) {
-  return value(json.oid, JSON.stringify(x) ?? null);
-}
-
-json.parse = function parse_json(s: string): unknown {
-  return JSON.parse(s);
-};
diff --git a/wire.ts b/wire.ts
index ccd8003..ea24504 100644
--- a/wire.ts
+++ b/wire.ts
@@ -1,10 +1,12 @@
 import {
+  type BinaryLike,
   buf_concat_fast,
   buf_eq,
   buf_xor,
   channel,
   from_base64,
   from_utf8,
+  jit,
   semaphore,
   semaphore_fast,
   to_base64,
@@ -28,21 +30,18 @@ import {
   i16,
   i32,
   i8,
+  type EncoderType,
 } from "./ser.ts";
-import {
-  is_sql,
-  sql,
-  type FromSql,
-  type SqlFragment,
-  type ToSql,
-} from "./sql.ts";
 import {
   type CommandResult,
+  is_sql,
   Query,
   type ResultStream,
   type Row,
-  row_ctor,
-  type RowConstructor,
+  sql,
+  type SqlFragment,
+  type SqlTypeMap,
+  text,
 } from "./query.ts";
 import { join } from "jsr:@std/path@^1.0.8";
 
@@ -446,8 +445,7 @@ export interface WireOptions {
   readonly password: string;
   readonly database: string | null;
   readonly runtime_params: Record<string, string>;
-  readonly from_sql: FromSql;
-  readonly to_sql: ToSql;
+  readonly types: SqlTypeMap;
 }
 
 export type WireEvents = {
@@ -542,7 +540,8 @@ export class Wire extends TypedEmitter<WireEvents> implements Disposable {
     if (typeof f !== "undefined") {
       await using tx = await this.#begin();
       const value = await f(this, tx);
-      return await tx.commit(), value;
+      if (tx.open) await tx.commit();
+      return value;
     } else {
       return this.#begin();
     }
@@ -583,7 +582,7 @@ export class Wire extends TypedEmitter<WireEvents> implements Disposable {
 function wire_impl(
   wire: Wire,
   socket: Deno.Conn,
-  { user, database, password, runtime_params, from_sql, to_sql }: WireOptions
+  { user, database, password, runtime_params, types }: WireOptions
 ) {
   const params: Parameters = Object.create(null);
 
@@ -878,45 +877,42 @@ function wire_impl(
   const st_cache = new Map<string, Statement>();
   let st_ids = 0;
 
-  function st_get(query: string, param_types: number[]) {
-    const key = JSON.stringify({ q: query, p: param_types });
-    let st = st_cache.get(key);
-    if (!st) st_cache.set(key, (st = new Statement(query, param_types)));
-    return st;
-  }
-
   class Statement {
     readonly name = `__st${st_ids++}`;
+    constructor(readonly query: string) {}
 
-    constructor(
-      readonly query: string,
-      readonly param_types: number[]
-    ) {}
+    parse_task: Promise<{
+      ser_params: ParameterSerializer;
+      Row: RowConstructor;
+    }> | null = null;
 
-    parse_task: Promise<RowConstructor> | null = null;
     parse() {
       return (this.parse_task ??= this.#parse());
     }
 
     async #parse() {
       try {
-        const { name, query, param_types } = this;
-        return row_ctor(
-          from_sql,
-          await pipeline(
-            async () => {
-              await write(Parse, { statement: name, query, param_types });
-              await write(Describe, { which: "S", name });
-            },
-            async () => {
-              await read(ParseComplete);
-              await read(ParameterDescription);
+        const { name, query } = this;
+        return await pipeline(
+          async () => {
+            await write(Parse, { statement: name, query, param_types: [] });
+            await write(Describe, { which: "S", name });
+          },
+          async () => {
+            await read(ParseComplete);
+            const param_desc = await read(ParameterDescription);
 
-              const msg = msg_check_err(await read_raw());
-              if (msg_type(msg) === NoData.type) return [];
-              else return ser_decode(RowDescription, msg).columns;
-            }
-          )
+            const msg = msg_check_err(await read_raw());
+            const row_desc =
+              msg_type(msg) === NoData.type
+                ? { columns: [] }
+                : ser_decode(RowDescription, msg);
+
+            return {
+              ser_params: param_ser(param_desc),
+              Row: row_ctor(row_desc),
+            };
+          }
         );
       } catch (e) {
         throw ((this.parse_task = null), e);
@@ -929,6 +925,59 @@ function wire_impl(
     }
   }
 
+  type ParameterDescription = EncoderType<typeof ParameterDescription>;
+  interface ParameterSerializer {
+    (params: unknown[]): (string | null)[];
+  }
+
+  function param_ser({ param_types }: ParameterDescription) {
+    return jit.compiled<ParameterSerializer>`function ser_params(xs) {
+      return [
+        ${jit.map(", ", param_types, (type_oid, i) => {
+          const type = types[type_oid] ?? text;
+          return jit`${type}.output(xs[${i}])`;
+        })}
+      ];
+    }`;
+  }
+
+  type RowDescription = EncoderType<typeof RowDescription>;
+  interface RowConstructor {
+    new (columns: (BinaryLike | null)[]): Row;
+  }
+
+  function row_ctor({ columns }: RowDescription) {
+    const Row = jit.compiled<RowConstructor>`function Row(xs) {
+      ${jit.map(" ", columns, ({ name, type_oid }, i) => {
+        const type = types[type_oid] ?? text;
+        return jit`this[${name}] = xs[${i}] === null ? null : ${type}.input(${from_utf8}(xs[${i}]));`;
+      })}
+    }`;
+
+    Row.prototype = Object.create(null, {
+      [Symbol.toStringTag]: {
+        configurable: true,
+        value: `Row`,
+      },
+      [Symbol.toPrimitive]: {
+        configurable: true,
+        value: function format() {
+          return [...this].join("\t");
+        },
+      },
+      [Symbol.iterator]: {
+        configurable: true,
+        value: jit.compiled`function* iter() {
+          ${jit.map(" ", columns, ({ name }) => {
+            return jit`yield this[${name}];`;
+          })}
+        }`,
+      },
+    });
+
+    return Row;
+  }
+
   async function read_rows(
     Row: RowConstructor,
     stdout: WritableStream<Uint8Array> | null
@@ -1002,7 +1051,7 @@ function wire_impl(
 
   async function* execute_fast(
     st: Statement,
-    params: { types: number[]; values: (string | null)[] },
+    params: unknown[],
     stdin: ReadableStream<Uint8Array> | null,
     stdout: WritableStream<Uint8Array> | null
   ): ResultStream<Row> {
@@ -1012,7 +1061,8 @@ function wire_impl(
       `executing query`
     );
 
-    const Row = await st.parse();
+    const { ser_params, Row } = await st.parse();
+    const param_values = ser_params(params);
     const portal = st.portal();
 
     try {
@@ -1022,7 +1072,7 @@ function wire_impl(
             portal,
             statement: st.name,
             param_formats: [],
-            param_values: params.values,
+            param_values,
             column_formats: [],
           });
           await write(Execute, { portal, row_limit: 0 });
@@ -1049,7 +1099,7 @@ function wire_impl(
 
   async function* execute_chunked(
     st: Statement,
-    params: { types: number[]; values: (string | null)[] },
+    params: unknown[],
     chunk_size: number,
     stdin: ReadableStream<Uint8Array> | null,
     stdout: WritableStream<Uint8Array> | null
@@ -1060,7 +1110,8 @@ function wire_impl(
       `executing chunked query`
     );
 
-    const Row = await st.parse();
+    const { ser_params, Row } = await st.parse();
+    const param_values = ser_params(params);
     const portal = st.portal();
 
     try {
@@ -1070,7 +1121,7 @@ function wire_impl(
             portal,
             statement: st.name,
             param_formats: [],
-            param_values: params.values,
+            param_values,
             column_formats: [],
           });
           await write(Execute, { portal, row_limit: chunk_size });
@@ -1103,8 +1154,9 @@ function wire_impl(
   }
 
   function query(s: SqlFragment) {
-    const { query, params } = sql.format(s, to_sql);
-    const st = st_get(query, params.types);
+    const { query, params } = sql.format(s);
+    let st = st_cache.get(query);
+    if (!st) st_cache.set(query, (st = new Statement(query)));
 
     return new Query(({ chunk_size = 0, stdin = null, stdout = null }) =>
       chunk_size !== 0
@@ -1287,7 +1339,8 @@ export class Pool
     if (typeof f !== "undefined") {
       await using tx = await this.#begin();
       const value = await f(tx.wire, tx);
-      return await tx.commit(), value;
+      if (tx.open) await tx.commit();
+      return value;
     } else {
       return this.#begin();
     }