feat(node): add blob v2 fetch and field helpers (#4155)

this PR blob v2 field helpers and reads to the Node SDK.

`blob()` marks a field as blob v2 and lets you set the storage
thresholds. Inputs can be bytes, a URI, or a data/uri struct.

Queries return descriptors. `fetchBlobs()` reads the bytes by row ID,
and `fetchBlobFiles()` gives you lazy handles for full or range reads.
`blobColumns()` lists the blob fields, including nested ones.

Fetch uses the table’s current checkout. It preserves order, duplicates,
and nulls. Holding row IDs across compaction still requires stable row
IDs.

```javascript
const db = await connect("./data");
const video = await readFile("clip.mp4");
const table = await db.createTable(
  "videos",
  [{ id: 1n, video }],
  {
    schema: new Schema([
      new Field("id", new Int64()),
      blob("video"),
    ]),
  },
);
const rows = await table.query().select(["id"]).withRowId().toArray();
const rowIds = rows.map((row) => row._rowid as bigint);
const bytes = await table.fetchBlobs("video", rowIds);
const [handle] = await table.fetchBlobFiles("video", rowIds);
const header = await handle!.readRange(0n, 65536n);

```

### Testing

- cover input validation, thresholds, nested fields, fetch ordering,
nulls, and range reads.
This commit is contained in:
Drew
2026-09-11 14:46:27 -07:00
committed by GitHub
parent e0bd4b5fa1
commit 6702e3fec1
15 changed files with 1260 additions and 17 deletions
+185
View File
@@ -0,0 +1,185 @@
// SPDX-License-Identifier: Apache-2.0
// SPDX-FileCopyrightText: Copyright The LanceDB Authors
import { Field, Int64, List, Schema, Struct, Utf8 } from "apache-arrow";
import { makeArrowTable } from "../lancedb/arrow";
import { BlobFile, blob, coerceBlobValue, isBlobField } from "../lancedb/blob";
describe("blob()", () => {
it("marks the field as lance.blob.v2", () => {
const field = blob("image", { nullable: false });
expect(field.nullable).toBe(false);
expect(isBlobField(field)).toBe(true);
expect(field.metadata.get("ARROW:extension:name")).toBe("lance.blob.v2");
});
it("writes encoding thresholds as field metadata", () => {
const field = blob("video", {
inlineSizeThreshold: 1024,
dedicatedSizeThreshold: 2 * 1024 * 1024,
packFileSizeThreshold: 64 * 1024 * 1024,
});
expect(
field.metadata.get("lance-encoding:blob-inline-size-threshold"),
).toBe("1024");
expect(
field.metadata.get("lance-encoding:blob-dedicated-size-threshold"),
).toBe(String(2 * 1024 * 1024));
expect(
field.metadata.get("lance-encoding:blob-pack-file-size-threshold"),
).toBe(String(64 * 1024 * 1024));
});
it("rejects invalid thresholds", () => {
expect(() => blob("image", { inlineSizeThreshold: -1 })).toThrow(
/inlineSizeThreshold must be non-negative/,
);
expect(() => blob("image", { dedicatedSizeThreshold: 0 })).toThrow(
/dedicatedSizeThreshold must be positive/,
);
expect(() => blob("image", { packFileSizeThreshold: 1.5 })).toThrow(
/packFileSizeThreshold must be a safe integer/,
);
expect(() =>
blob("image", { dedicatedSizeThreshold: Number.MAX_SAFE_INTEGER + 1 }),
).toThrow(/dedicatedSizeThreshold must be a safe integer/);
});
});
describe("coerceBlobValue", () => {
it.each([
["Buffer", Buffer.from("x"), { data: Buffer.from("x"), uri: null }],
[
"Uint8Array",
new Uint8Array([120]),
{ data: new Uint8Array([120]), uri: null },
],
["URI string", "s3://bucket/key", { data: null, uri: "s3://bucket/key" }],
[
"data struct",
{ data: Buffer.from("y") },
{ data: Buffer.from("y"), uri: null },
],
[
"uri struct",
{ uri: "s3://bucket/key" },
{ data: null, uri: "s3://bucket/key" },
],
["null", null, null],
])("accepts %s", (_name, input, expected) => {
expect(coerceBlobValue(input)).toEqual(expected);
});
it.each([
["empty URI", "", /uri cannot be empty/],
["object without data or uri", { position: 0 }, /data' or 'uri/],
[
"Int16Array",
new Int16Array([1]),
/Blob data must be Buffer or Uint8Array/,
],
[
"both data and uri",
{ data: Buffer.from("y"), uri: "s3://bucket/key" },
/exactly one of 'data' or 'uri'/,
],
[
"neither data nor uri",
{ data: null, uri: null },
/exactly one of 'data' or 'uri'/,
],
])("rejects %s", (_name, input, message) => {
expect(() => coerceBlobValue(input)).toThrow(message);
});
});
describe("BlobFile", () => {
it("rejects constructing BlobFile without a native handle", () => {
expect(() => new (BlobFile as unknown as { new (): BlobFile })()).toThrow(
/fetchBlobFiles/,
);
});
});
describe("makeArrowTable blob columns", () => {
it("coerces Buffer input onto a blob field", () => {
const schema = new Schema([
new Field("id", new Int64(), true),
blob("image"),
]);
const table = makeArrowTable([{ id: 1n, image: Buffer.from("hello") }], {
schema,
});
expect(isBlobField(table.schema.fields[1])).toBe(true);
const image = table.getChild("image")!;
expect(image.nullCount).toBe(0);
expect(image.getChild("uri")!.get(0)).toBeNull();
expect(image.getChild("data")!.nullCount).toBe(0);
expect(Buffer.from(image.getChild("data")!.get(0)!).toString()).toBe(
"hello",
);
});
it("coerces Buffer elements inside a list and keeps null slots", () => {
const schema = new Schema([
new Field("id", new Int64(), true),
new Field("images", new List(blob("image")), true),
]);
const table = makeArrowTable(
[
{ id: 1n, images: [Buffer.from("a"), Buffer.from("bb")] },
{ id: 2n, images: null },
{ id: 3n, images: [Buffer.from("c"), null] },
{ id: 4n, images: [] },
],
{ schema },
);
const images = table.getChild("images")!;
expect(images.nullCount).toBe(1);
const rows = images.toArray();
expect(rows[1]).toBeNull();
expect(Array.from(rows[3] as Iterable<unknown>)).toHaveLength(0);
const first = Array.from(rows[0] as Iterable<{ data: Uint8Array | null }>);
expect(Buffer.from(first[0].data!).toString()).toBe("a");
expect(Buffer.from(first[1].data!).toString()).toBe("bb");
const third = Array.from(
rows[2] as Iterable<{ data: Uint8Array | null } | null>,
);
expect(Buffer.from(third[0]!.data!).toString()).toBe("c");
expect(third[1]).toBeNull();
});
it("coerces Buffer fields inside list structs", () => {
const schema = new Schema([
new Field("id", new Int64(), true),
new Field(
"items",
new List(
new Field(
"item",
new Struct([new Field("name", new Utf8(), true), blob("image")]),
true,
),
),
true,
),
]);
const table = makeArrowTable(
[
{
id: 1n,
items: [{ name: "one", image: Buffer.from("alpha") }],
},
],
{ schema },
);
const items = Array.from(
table.getChild("items")!.toArray()[0] as Iterable<{
name: string;
image: { data: Uint8Array | null };
}>,
);
expect(items[0].name).toBe("one");
expect(Buffer.from(items[0].image.data!).toString()).toBe("alpha");
});
});
+271
View File
@@ -18,6 +18,7 @@ import {
Query,
Table,
VectorQuery,
blob,
connect,
tokenize,
} from "../lancedb";
@@ -2401,6 +2402,276 @@ describe("when dealing with versioning", () => {
});
});
describe("when dealing with blob columns", () => {
let tmpDir: tmp.DirResult;
beforeEach(() => {
tmpDir = tmp.dirSync({ unsafeCleanup: true });
});
afterEach(() => {
tmpDir.removeCallback();
});
it("discovers blob columns", async () => {
const { table } = await openBlobTable();
expect(await table.blobColumns()).toEqual(["image"]);
});
it("preserves order, duplicates, and nulls", async () => {
const { table, rowIds } = await openBlobTable();
const [alphaId, betaId, nullId] = rowIds;
const bytes = await table.fetchBlobs("image", [
betaId,
alphaId,
betaId,
nullId,
]);
expect(bytes.map((b) => (b == null ? null : b.toString()))).toEqual([
"beta",
"alpha",
"beta",
null,
]);
const files = await table.fetchBlobFiles("image", [
betaId,
nullId,
alphaId,
]);
expect(files.map((f) => f == null)).toEqual([false, true, false]);
});
it("reads full blob contents", async () => {
const { table, rowIds, alpha, beta } = await openBlobTable();
const bytes = await table.fetchBlobs("image", rowIds);
expect(bytes[0]!.equals(alpha)).toBe(true);
expect(bytes[1]!.equals(beta)).toBe(true);
const files = await table.fetchBlobFiles("image", rowIds);
expect(files[0]!.size()).toBe(BigInt(alpha.length));
expect(Buffer.from(await files[0]!.read()).toString()).toBe("alpha");
expect(Buffer.from(await files[1]!.read()).toString()).toBe("beta");
});
it("reads a half-open range", async () => {
const { table, rowIds } = await openBlobTable();
const files = await table.fetchBlobFiles("image", rowIds);
expect(Buffer.from(await files[0]!.readRange(0n, 2n)).toString()).toBe(
"al",
);
});
it("readRange does not move the cursor", async () => {
const { table, rowIds, alpha } = await openBlobTable();
const [handle] = await table.fetchBlobFiles("image", rowIds);
expect((await handle!.readRange(1n, 3n)).toString()).toBe("lp");
expect(await handle!.read()).toEqual(alpha);
expect(await handle!.read()).toEqual(Buffer.alloc(0));
});
it("fails when readRange end is past the blob size", async () => {
const { table, rowIds, alpha } = await openBlobTable();
const files = await table.fetchBlobFiles("image", rowIds);
await expect(
files[0]!.readRange(0n, BigInt(alpha.length + 1)),
).rejects.toThrow(/exceeds blob size/);
});
it("rejects fetchBlobs on a non-blob column", async () => {
const { table, rowIds } = await openBlobTable();
await expect(table.fetchBlobs("id", rowIds)).rejects.toThrow(/blob/i);
});
it("discovers and fetches nested blob columns", async () => {
const db = await connect(tmpDir.name);
const schema = new Schema([
new Field("id", new Int64(), true),
new Field("info", new Struct([blob("image")]), true),
]);
const payload = Buffer.from("nested");
const table = await db.createTable(
"nested_blobs",
[{ id: 1n, info: { image: payload } }],
{ schema },
);
expect(await table.blobColumns()).toEqual(["info.image"]);
const rows = await table.query().withRowId().toArray();
const bytes = await table.fetchBlobs("info.image", [
rows[0]._rowid as bigint,
]);
expect(bytes[0]!.equals(payload)).toBe(true);
});
it("creates and adds list blob columns", async () => {
const db = await connect(tmpDir.name);
const schema = new Schema([
new Field("id", new Int64(), true),
new Field("images", new List(blob("image")), true),
]);
const alpha = Buffer.from("alpha");
const beta = Buffer.from("beta");
const gamma = Buffer.from("gamma");
const table = await db.createTable(
"list_blobs",
[{ id: 1n, images: [alpha, beta] }],
{ schema },
);
await table.add([
{ id: 2n, images: null },
{ id: 3n, images: [gamma, null] },
{ id: 4n, images: [] },
]);
expect(await table.blobColumns()).toEqual(["images.image"]);
const rows = await table.query().toArray();
const byId = new Map(rows.map((row) => [Number(row.id), row]));
expect(descriptorSizes(byId.get(1)!.images)).toEqual([
alpha.length,
beta.length,
]);
expect(byId.get(2)!.images).toBeNull();
expect(descriptorSizes(byId.get(3)!.images)).toEqual([gamma.length, null]);
expect(Array.from(byId.get(4)!.images as Iterable<unknown>)).toHaveLength(
0,
);
});
it("creates and adds list struct blob columns", async () => {
const db = await connect(tmpDir.name);
const schema = new Schema([
new Field("id", new Int64(), true),
new Field(
"items",
new List(
new Field(
"item",
new Struct([new Field("name", new Utf8(), true), blob("image")]),
true,
),
),
true,
),
]);
const alpha = Buffer.from("nested-alpha");
const beta = Buffer.from("nested-beta");
const table = await db.createTable(
"list_struct_blobs",
[{ id: 1n, items: [{ name: "one", image: alpha }] }],
{ schema },
);
await table.add([
{
id: 2n,
items: [
{ name: "two", image: beta },
{ name: "three", image: null },
],
},
]);
const rows = await table.query().toArray();
const byId = new Map(rows.map((row) => [Number(row.id), row]));
expect(
descriptorSizes(
Array.from(byId.get(1)!.items as Iterable<{ image: unknown }>).map(
(item) => item.image,
),
),
).toEqual([alpha.length]);
expect(
descriptorSizes(
Array.from(byId.get(2)!.items as Iterable<{ image: unknown }>).map(
(item) => item.image,
),
),
).toEqual([beta.length, null]);
});
it("rejects blob fields inside a fixed-size list", async () => {
const db = await connect(tmpDir.name);
const schema = new Schema([
new Field("id", new Int64(), true),
new Field("frames", new FixedSizeList(2, blob("frame")), true),
]);
await expect(
db.createTable(
"fsl_blobs",
[{ id: 1n, frames: [Buffer.from("a"), Buffer.from("b")] }],
{ schema },
),
).rejects.toThrow(
"Blob fields inside FixedSizeList are not supported. Use List instead.",
);
});
it("rejects blob fields inside a nested fixed-size list", async () => {
const db = await connect(tmpDir.name);
const schema = new Schema([
new Field("id", new Int64(), true),
new Field(
"clip",
new Struct([
new Field("frames", new FixedSizeList(2, blob("frame")), true),
]),
true,
),
]);
await expect(
db.createTable(
"nested_fsl_blobs",
[
{
id: 1n,
clip: { frames: [Buffer.from("a"), Buffer.from("b")] },
},
],
{ schema },
),
).rejects.toThrow(
"Blob fields inside FixedSizeList are not supported. Use List instead.",
);
});
it("rejects an Arrow table with blob fields inside a fixed-size list", async () => {
const db = await connect(tmpDir.name);
const schema = new Schema([
new Field("id", new Int64(), true),
new Field("frames", new FixedSizeList(2, blob("frame")), true),
]);
await expect(
db.createTable("fsl_blobs_ipc", new ArrowTable(schema)),
).rejects.toThrow(
"Blob fields inside FixedSizeList are not supported. Use List instead.",
);
});
function descriptorSizes(values: unknown): (number | null)[] {
return Array.from(
values as Iterable<{ size?: bigint | number } | null>,
).map((value) => (value == null ? null : Number(value.size)));
}
async function openBlobTable() {
const db = await connect(tmpDir.name);
const schema = new Schema([
new Field("id", new Int64(), true),
blob("image"),
]);
const alpha = Buffer.from("alpha");
const beta = Buffer.from("beta");
const table = await db.createTable(
"blobs",
[
{ id: 1n, image: alpha },
{ id: 2n, image: beta },
{ id: 3n, image: null },
],
{ schema },
);
const rows = await table.query().withRowId().toArray();
const rowIdById = new Map(
rows.map((r) => [Number(r.id), r._rowid as bigint]),
);
const rowIds = [1, 2, 3].map((id) => rowIdById.get(id)!);
return { table, rowIds, alpha, beta };
}
});
describe("when dealing with tags", () => {
let tmpDir: tmp.DirResult;
beforeEach(() => {