Type Inference

Overview

The library exports utility types that extract row types from table definitions. These are useful for typing function parameters, API responses, and more.

import type {
  InferRow,
  InferInsertRow,
  InferUpdateRow,
} from "@fcannizzaro/questdb-typesafe-client";

InferRow

The full row type as returned by SELECT queries:

const sensors = defineTable({
  name: "sensors",
  columns: {
    ts: q.timestamp.designated(),
    source: q.symbol(),
    power_kw: q.double(),
    meter_active: q.boolean(),
  },
  partitionBy: "DAY",
});

type Row = InferRow<typeof sensors>;
// {
//   ts: Date | null;
//   source: string | null;
//   power_kw: number | null;
//   meter_active: boolean;       // non-nullable
// }

Nullability Rules (Read)

Type	Nullable?	Reason
`boolean`, `byte`, `short`	No	QuestDB defaults them to `false` / `0`
All other types	Yes	Can be `NULL` in QuestDB

InferInsertRow

The row type accepted by INSERT operations:

type InsertRow = InferInsertRow<typeof sensors>;
// {
//   meter_active: boolean;          // required (non-nullable)
//   ts?: Date | null | undefined;   // optional (designated timestamp)
//   source?: string | null;         // optional (nullable)
//   power_kw?: number | null;       // optional (nullable)
// }

Insert Rules

Non-nullable types (boolean, byte, short) are required
Designated timestamp is optional (server auto-assigns current time)
All nullable columns are optional and accept T | null | undefined
undefined values are excluded from the generated SQL

InferUpdateRow

The row type accepted by UPDATE .set():

type UpdateRow = InferUpdateRow<typeof sensors>;
// {
//   source?: string | null;
//   power_kw?: number | null;
//   meter_active?: boolean;
// }

Update Rules

Designated timestamp is excluded — QuestDB does not allow updating the designated timestamp
All other columns are Partial (optional)

PickColumns

Narrow a row type to specific columns:

import type { PickColumns } from "@fcannizzaro/questdb-typesafe-client";

type Subset = PickColumns<typeof sensors, "source" | "power_kw">;
// { source: string | null; power_kw: number | null }

JoinRow

Merge two row types with alias-prefixed keys (used internally by join builders):

import type { JoinRow } from "@fcannizzaro/questdb-typesafe-client";

type Joined = JoinRow<LeftRow, RightRow, "q", true>;
// LeftRow & { "q.col1": Type | null; "q.col2": Type | null; ... }

The fourth parameter controls whether right-side columns are nullable (true for ASOF/LT/LEFT/SPLICE joins, false for INNER/CROSS joins).

Type Inference

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