Files
lancedb/nodejs/__test__/query.test.ts
lancedb-gatefixer[bot] 7e979c1416 fix(node): preserve schemas for empty query results (#4423)
Empty local TypeScript queries returned a zero-row Arrow table with no
columns because `toArrow()` built the table solely from record batches.
Local streams can yield no batches, while remote streams often supply an
empty batch carrying the schema.

Expose the executed stream's schema through the native iterator and
decode it into an empty Arrow table when no batches arrive. This
preserves projected and search columns, types, nullability, and metadata
without executing another query. Document the empty-result behavior.

Validation:

- Eleven regression cases failed with the original `toArrow()`
implementation; all twelve now pass, including remote schema-only and
empty-batch responses.
- All 1,075 tests in the query, remote, Arrow, and table suites pass.
- Native build, TypeScript compilation, Rust formatting and Clippy (`-D
warnings`), TypeScript lint/formatting, and documentation generation
pass.

Fixes #4386

<!-- lance-gatekeeper-fix:v1 agent=7d589da1f7db5c7383f9600490e111a9
generation=1 -->

Co-authored-by: Gatefixer <313497061+lancedb-gatefixer[bot]@users.noreply.github.com>
2026-10-03 05:56:50 -05:00

530 lines
16 KiB
TypeScript

// SPDX-License-Identifier: Apache-2.0
// SPDX-FileCopyrightText: Copyright The LanceDB Authors
import * as tmp from "tmp";
import { type Table, connect } from "../lancedb";
import {
Field,
FixedSizeList,
Float32,
Int64,
Schema,
Utf8,
makeArrowTable,
} from "../lancedb/arrow";
import { Index } from "../lancedb/indices";
describe("Query outputSchema", () => {
let tmpDir: tmp.DirResult;
let table: Table;
beforeEach(async () => {
tmpDir = tmp.dirSync({ unsafeCleanup: true });
const db = await connect(tmpDir.name);
// Create table with explicit schema to ensure proper types
const schema = new Schema([
new Field("a", new Int64(), true),
new Field("text", new Utf8(), true),
new Field(
"vec",
new FixedSizeList(2, new Field("item", new Float32())),
true,
),
]);
const data = makeArrowTable(
[
{ a: 1n, text: "foo", vec: [1, 2] },
{ a: 2n, text: "bar", vec: [3, 4] },
{ a: 3n, text: "baz", vec: [5, 6] },
],
{ schema },
);
table = await db.createTable("test", data);
});
afterEach(() => {
tmpDir.removeCallback();
});
it("should return schema for plain query", async () => {
const schema = await table.query().outputSchema();
expect(schema.fields.length).toBe(3);
expect(schema.fields.map((f) => f.name)).toEqual(["a", "text", "vec"]);
expect(schema.fields[0].type.toString()).toBe("Int64");
expect(schema.fields[1].type.toString()).toBe("Utf8");
});
it("should return schema with dynamic projection", async () => {
const schema = await table.query().select({ bl: "a * 2" }).outputSchema();
expect(schema.fields.length).toBe(1);
expect(schema.fields[0].name).toBe("bl");
expect(schema.fields[0].type.toString()).toBe("Int64");
});
it("should return schema for vector search with _distance column", async () => {
const schema = await table
.vectorSearch([1, 2])
.select(["a"])
.outputSchema();
expect(schema.fields.length).toBe(2);
expect(schema.fields.map((f) => f.name)).toEqual(["a", "_distance"]);
expect(schema.fields[0].type.toString()).toBe("Int64");
expect(schema.fields[1].type.toString()).toBe("Float32");
});
it("should return schema for FTS search", async () => {
await table.createIndex("text", { config: Index.fts() });
const schema = await table
.search("foo", "fts")
.select(["a"])
.outputSchema();
// FTS search includes _score column in addition to selected columns
expect(schema.fields.length).toBe(2);
expect(schema.fields.map((f) => f.name)).toContain("a");
expect(schema.fields.map((f) => f.name)).toContain("_score");
const aField = schema.fields.find((f) => f.name === "a");
expect(aField?.type.toString()).toBe("Int64");
});
it("should return schema for take query", async () => {
const schema = await table.takeOffsets([0]).select(["text"]).outputSchema();
expect(schema.fields.length).toBe(1);
expect(schema.fields[0].name).toBe("text");
expect(schema.fields[0].type.toString()).toBe("Utf8");
});
it("should return full schema when no select is specified", async () => {
const schema = await table.query().outputSchema();
// Should return all columns
expect(schema.fields.length).toBe(3);
});
});
describe("Query empty results", () => {
let tmpDir: tmp.DirResult;
let table: Table;
beforeEach(async () => {
tmpDir = tmp.dirSync({ unsafeCleanup: true });
const db = await connect(tmpDir.name);
const schema = new Schema(
[
new Field("id", new Int64(), false),
new Field(
"text",
new Utf8(),
true,
new Map([["description", "searchable text"]]),
),
new Field(
"vector",
new FixedSizeList(2, new Field("item", new Float32())),
true,
),
],
new Map([["source", "empty-query-regression"]]),
);
table = await db.createTable(
"test",
makeArrowTable([{ id: 1n, text: "hello", vector: [1, 2] }], { schema }),
);
});
afterEach(() => {
tmpDir.removeCallback();
});
it.each([
{
name: "filtered scan",
query: (table: Table) => table.query().where("id < 0"),
fields: ["id", "text", "vector"],
},
{
name: "zero limit",
query: (table: Table) => table.query().limit(0),
fields: ["id", "text", "vector"],
},
{
name: "column projection",
query: (table: Table) =>
table.query().where("id < 0").select(["text", "id"]),
fields: ["text", "id"],
},
{
name: "dynamic projection",
query: (table: Table) =>
table.query().where("id < 0").select({ doubled: "id * 2" }),
fields: ["doubled"],
},
{
name: "filtered vector search",
query: (table: Table) =>
table.search([0.5, 0.5]).where("id < 0").limit(3),
fields: ["id", "text", "vector", "_distance"],
},
{
name: "vector projection with row id",
query: (table: Table) =>
table
.vectorSearch([0.5, 0.5])
.where("id < 0")
.select(["id"])
.withRowId(),
fields: ["id", "_distance", "_rowid"],
},
{
name: "fast search without an index",
query: (table: Table) => table.search([0.5, 0.5]).fastSearch(),
fields: ["id", "text", "vector", "_rowid", "_distance"],
},
{
name: "take with no offsets",
query: (table: Table) => table.takeOffsets([]).select(["text"]),
fields: ["text"],
},
])("preserves the output schema for $name", async ({ query, fields }) => {
const result = await query(table).toArrow({ maxBatchLength: 1 });
expect(result.numRows).toBe(0);
expect(result.schema.fields.map((field) => field.name)).toEqual(fields);
for (const name of fields) {
expect(result.getChild(name)).not.toBeNull();
expect(result.getChild(name)?.length).toBe(0);
}
});
it("preserves types, nullability, and metadata", async () => {
const result = await table.query().where("id < 0").toArrow();
const schema = await table.schema();
expect(result.schema).toEqual(schema);
expect(result.getChild("id")?.type.toString()).toBe("Int64");
expect(result.schema.fields[0].nullable).toBe(false);
expect(result.schema.fields[1].metadata.get("description")).toBe(
"searchable text",
);
expect(result.schema.metadata.get("source")).toBe("empty-query-regression");
});
it("preserves the score column for full-text search with no matches", async () => {
await table.createIndex("text", { config: Index.fts() });
const result = await table
.search("missing", "fts")
.select(["id"])
.toArrow();
expect(result.numRows).toBe(0);
expect(result.schema.fields.map((field) => field.name)).toEqual([
"id",
"_score",
]);
expect(result.getChild("_score")?.type.toString()).toBe("Float32");
});
});
describe("Search pagination", () => {
let tmpDir: tmp.DirResult;
let table: Table;
beforeEach(async () => {
tmpDir = tmp.dirSync({ unsafeCleanup: true });
const db = await connect(tmpDir.name);
const schema = new Schema([
new Field("id", new Int64(), false),
new Field("text", new Utf8(), false),
new Field(
"vector",
new FixedSizeList(2, new Field("item", new Float32())),
false,
),
]);
const data = makeArrowTable(
[
{ id: 1n, text: "common", vector: [0, 0] },
{ id: 2n, text: "common common", vector: [1, 1] },
{ id: 3n, text: "common common common", vector: [2, 2] },
{ id: 4n, text: "common common common common", vector: [3, 3] },
],
{ schema },
);
table = await db.createTable("test", data);
});
afterEach(() => {
tmpDir.removeCallback();
});
it("applies offset after the vector search limit", async () => {
const allResults = await table
.vectorSearch([0, 0])
.select(["id"])
.limit(4)
.toArray();
const secondPage = await table
.vectorSearch([0, 0])
.select(["id"])
.limit(2)
.offset(2)
.toArray();
expect(allResults).toHaveLength(4);
expect(secondPage).toHaveLength(2);
expect(secondPage.map((row) => row.id)).toEqual(
allResults.slice(2, 4).map((row) => row.id),
);
});
it("applies offset after the full-text search limit", async () => {
await table.createIndex("text", { config: Index.fts() });
const allResults = await table
.search("common", "fts")
.select(["id"])
.limit(4)
.toArray();
const secondPage = await table
.search("common", "fts")
.select(["id"])
.limit(2)
.offset(2)
.toArray();
expect(allResults).toHaveLength(4);
expect(secondPage).toHaveLength(2);
expect(secondPage.map((row) => row.id)).toEqual(
allResults.slice(2, 4).map((row) => row.id),
);
});
});
describe("Query orderBy", () => {
let tmpDir: tmp.DirResult;
let table: Table;
beforeEach(async () => {
tmpDir = tmp.dirSync({ unsafeCleanup: true });
const db = await connect(tmpDir.name);
// Create table with numeric data for sorting
const schema = new Schema([
new Field("id", new Int64(), true),
new Field("score", new Float32(), true),
new Field("name", new Utf8(), true),
]);
const data = makeArrowTable(
[
{ id: 1n, score: 3.5, name: "charlie" },
{ id: 2n, score: 1.2, name: "alice" },
{ id: 3n, score: 2.8, name: "bob" },
{ id: 4n, score: 0.5, name: "david" },
{ id: 5n, score: 4.1, name: "eve" },
],
{ schema },
);
table = await db.createTable("test", data);
});
afterEach(() => {
tmpDir.removeCallback();
});
it("should sort by single column ascending", async () => {
const results = await table
.query()
.orderBy({ columnName: "score", ascending: true, nullsFirst: false })
.toArray();
expect(results.length).toBe(5);
// Verify ascending order
expect(results[0].score).toBeCloseTo(0.5, 0.001);
expect(results[1].score).toBeCloseTo(1.2, 0.001);
expect(results[2].score).toBeCloseTo(2.8, 0.001);
expect(results[3].score).toBeCloseTo(3.5, 0.001);
expect(results[4].score).toBeCloseTo(4.1, 0.001);
});
it("should sort by single column descending", async () => {
const results = await table
.query()
.orderBy({ columnName: "score", ascending: false, nullsFirst: false })
.toArray();
expect(results.length).toBe(5);
// Verify descending order
expect(results[0].score).toBeCloseTo(4.1, 0.001);
expect(results[1].score).toBeCloseTo(3.5, 0.001);
expect(results[2].score).toBeCloseTo(2.8, 0.001);
expect(results[3].score).toBeCloseTo(1.2, 0.001);
expect(results[4].score).toBeCloseTo(0.5, 0.001);
});
it("should use ascending as default direction", async () => {
const results = await table
.query()
.orderBy({ columnName: "score" })
.toArray();
expect(results.length).toBe(5);
// Verify ascending order (default)
expect(results[0].score).toBeCloseTo(0.5, 0.001);
expect(results[1].score).toBeCloseTo(1.2, 0.001);
expect(results[2].score).toBeCloseTo(2.8, 0.001);
expect(results[3].score).toBeCloseTo(3.5, 0.001);
expect(results[4].score).toBeCloseTo(4.1, 0.001);
});
it("should sort by string column", async () => {
const results = await table
.query()
.orderBy({ columnName: "name" })
.toArray();
expect(results.length).toBe(5);
// Verify alphabetical order
expect(results[0].name).toBe("alice");
expect(results[1].name).toBe("bob");
expect(results[2].name).toBe("charlie");
expect(results[3].name).toBe("david");
expect(results[4].name).toBe("eve");
});
it("should support method chaining with where", async () => {
const results = await table
.query()
.where("score > 2.0")
.orderBy({ columnName: "score" })
.toArray();
expect(results.length).toBe(3);
// Verify filtered and sorted
expect(results[0].score).toBeCloseTo(2.8, 0.001);
expect(results[1].score).toBeCloseTo(3.5, 0.001);
expect(results[2].score).toBeCloseTo(4.1, 0.001);
});
it("should combine repeated where clauses with AND", async () => {
const results = await table
.query()
.where("score > 1.0")
.where("score < 3.0")
.orderBy({ columnName: "score" })
.toArray();
// Only rows matching both predicates should be returned, rather than the
// second where() silently replacing the first.
expect(results.length).toBe(2);
expect(results[0].score).toBeCloseTo(1.2, 0.001);
expect(results[1].score).toBeCloseTo(2.8, 0.001);
});
it("should support method chaining with limit", async () => {
const results = await table
.query()
.orderBy({ columnName: "score", ascending: false })
.limit(3)
.toArray();
expect(results.length).toBe(3);
// Verify top 3 in descending order
expect(results[0].score).toBeCloseTo(4.1, 0.001);
expect(results[1].score).toBeCloseTo(3.5, 0.001);
expect(results[2].score).toBeCloseTo(2.8, 0.001);
});
it("should support method chaining with offset", async () => {
const results = await table
.query()
.orderBy({ columnName: "score" })
.offset(2)
.limit(2)
.toArray();
expect(results.length).toBe(2);
// Verify results skip first 2 and take next 2
expect(results[0].score).toBeCloseTo(2.8, 0.001);
expect(results[1].score).toBeCloseTo(3.5, 0.001);
});
it("should support method chaining with select", async () => {
const results = await table
.query()
.orderBy({ columnName: "name" })
.select(["name", "score"])
.toArray();
expect(results.length).toBe(5);
// Verify only selected columns are present
expect(Object.keys(results[0])).toEqual(["name", "score"]);
expect(Object.keys(results[4])).toEqual(["name", "score"]);
// Verify sorted by name
expect(results[0].name).toBe("alice");
expect(results[4].name).toBe("eve");
});
it("should support complex method chaining", async () => {
const results = await table
.query()
.where("score > 1.0")
.orderBy({ columnName: "score", ascending: false })
.limit(3)
.select(["id", "score", "name"])
.toArray();
expect(results.length).toBe(3);
// Verify filtered, sorted, limited, and projected
expect(results[0].score).toBeCloseTo(4.1, 0.001);
expect(results[1].score).toBeCloseTo(3.5, 0.001);
expect(results[2].score).toBeCloseTo(2.8, 0.001);
expect(Object.keys(results[0])).toEqual(["id", "score", "name"]);
});
it("should support multi-column ordering and null placement", async () => {
const schema = new Schema([
new Field("group", new Int64(), true),
new Field("score", new Float32(), true),
new Field("name", new Utf8(), true),
]);
const data = makeArrowTable(
[
{ group: 1n, score: null, name: "z" },
{ group: 1n, score: 1.0, name: "b" },
{ group: 1n, score: 1.0, name: "a" },
{ group: 2n, score: 0.5, name: "c" },
],
{ schema },
);
const nullTable = await (await connect(tmpDir.name)).createTable(
"test_multi_order",
data,
{ mode: "overwrite" },
);
const results = await nullTable
.query()
.orderBy([
{ columnName: "group", ascending: true, nullsFirst: false },
{ columnName: "score", ascending: true, nullsFirst: true },
{ columnName: "name", ascending: true, nullsFirst: false },
])
.toArray();
expect(results.map((r) => [r.group, r.score, r.name])).toEqual([
[1n, null, "z"],
[1n, 1.0, "a"],
[1n, 1.0, "b"],
[2n, 0.5, "c"],
]);
});
});