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15 changes: 14 additions & 1 deletion docs/faq/faq-oss.mdx
Original file line number Diff line number Diff line change
Expand Up @@ -44,7 +44,20 @@ For large-scale (>1M) or higher dimension vectors, it is beneficial to create a

### How can I speed up data inserts?

It's highly recommended to perform bulk inserts via batches (for e.g., Pandas DataFrames or lists of dicts in Python) to speed up inserts for large datasets. Inserting records one at a time is slow and can result in suboptimal performance because each insert creates a new data fragment on disk. Batching inserts allows LanceDB to create larger fragments (and their associated manifests), which are more efficient to read and write.
LanceDB auto-parallelizes large writes when you call `table.add()` with materialized
data such as `pa.Table`, `pd.DataFrame`, or `pa.dataset()`. No extra configuration
is needed — writes are automatically split into partitions of ~1M rows or 2GB.

For best results:

- **Create an empty table first**, then call `table.add()`. The `add()` path enables
automatic write parallelism, while passing data directly to `create_table()` does not.
- **For file-based data**, use `pyarrow.dataset.dataset("path/to/data/", format="parquet")`
so LanceDB can stream from disk without loading everything into memory.
- **Avoid inserting one row at a time.** Each insert creates a new data fragment on
disk. Batch your data into Arrow tables, DataFrames, or use iterators.

See [Loading Large Datasets](/tables/create#loading-large-datasets) for full examples.

### Do I need to set a refine factor when using an index?

Expand Down
4 changes: 2 additions & 2 deletions docs/snippets/quickstart.mdx
Original file line number Diff line number Diff line change
Expand Up @@ -18,6 +18,8 @@ export const PyQuickstartVectorSearch1Async = "# Let's search for vectors simila

export const PyQuickstartVectorSearch2 = "# Let's search for vectors similar to \"wizard\"\nquery_vector = [0.7, 0.3, 0.5]\n\nresults = table.search(query_vector).limit(2).to_polars()\nprint(results)\n";

export const TsQuickstartOutputPandas = "result = await table.search(queryVector).limit(2).toArray();\n";

export const TsQuickstartAddData = "const moreData = [\n { id: \"7\", text: \"mage\", vector: [0.6, 0.3, 0.4] },\n { id: \"8\", text: \"bard\", vector: [0.3, 0.8, 0.4] },\n];\n\n// Add data to table\nawait table.add(moreData);\n";

export const TsQuickstartCreateTable = "const data = [\n { id: \"1\", text: \"knight\", vector: [0.9, 0.4, 0.8] },\n { id: \"2\", text: \"ranger\", vector: [0.8, 0.4, 0.7] },\n { id: \"9\", text: \"priest\", vector: [0.6, 0.2, 0.6] },\n { id: \"4\", text: \"rogue\", vector: [0.7, 0.4, 0.7] },\n];\nlet table = await db.createTable(\"adventurers\", data, { mode: \"overwrite\" });\n";
Expand All @@ -28,8 +30,6 @@ export const TsQuickstartOpenTable = "table = await db.openTable(\"adventurers\"

export const TsQuickstartOutputArray = "result = await table.search(queryVector).limit(2).toArray();\nconsole.table(result);\n";

export const TsQuickstartOutputPandas = "result = await table.search(queryVector).limit(2).toArray();\n";

export const TsQuickstartVectorSearch1 = "// Let's search for vectors similar to \"warrior\"\nlet queryVector = [0.8, 0.3, 0.8];\n\nlet result = await table.search(queryVector).limit(2).toArray();\nconsole.table(result);\n";

export const TsQuickstartVectorSearch2 = "// Let's search for vectors similar to \"wizard\"\nqueryVector = [0.7, 0.3, 0.5];\n\nconst results = await table.search(queryVector).limit(2).toArray();\nconsole.table(results);\n";
Expand Down
4 changes: 2 additions & 2 deletions docs/snippets/search.mdx
Original file line number Diff line number Diff line change
Expand Up @@ -8,10 +8,10 @@ export const PyBasicHybridSearch = "data = [\n {\"text\": \"rebel spaceships

export const PyBasicHybridSearchAsync = "uri = \"data/sample-lancedb\"\nasync_db = await lancedb.connect_async(uri)\ndata = [\n {\"text\": \"rebel spaceships striking from a hidden base\"},\n {\"text\": \"have won their first victory against the evil Galactic Empire\"},\n {\"text\": \"during the battle rebel spies managed to steal secret plans\"},\n {\"text\": \"to the Empire's ultimate weapon the Death Star\"},\n]\nasync_tbl = await async_db.create_table(\"documents_async\", schema=Documents)\n# ingest docs with auto-vectorization\nawait async_tbl.add(data)\n# Create a fts index before the hybrid search\nawait async_tbl.create_index(\"text\", config=FTS())\ntext_query = \"flower moon\"\n# hybrid search with default re-ranker\nawait (await async_tbl.search(\"flower moon\", query_type=\"hybrid\")).to_pandas()\n";

export const PyClassDefinition = "class Metadata(BaseModel):\n source: str\n timestamp: datetime\n\n\nclass Document(BaseModel):\n content: str\n meta: Metadata\n\n\nclass LanceSchema(LanceModel):\n id: str\n vector: Vector(1536)\n payload: Document\n";

export const PyClassDocuments = "class Documents(LanceModel):\n vector: Vector(embeddings.ndims()) = embeddings.VectorField()\n text: str = embeddings.SourceField()\n";

export const PyClassDefinition = "class Metadata(BaseModel):\n source: str\n timestamp: datetime\n\n\nclass Document(BaseModel):\n content: str\n meta: Metadata\n\n\nclass LanceSchema(LanceModel):\n id: str\n vector: Vector(1536)\n payload: Document\n";

export const PyCreateTableAsyncWithNestedSchema = "# Let's add 100 sample rows to our dataset\ndata = [\n LanceSchema(\n id=f\"id{i}\",\n vector=np.random.randn(1536),\n payload=Document(\n content=f\"document{i}\",\n meta=Metadata(source=f\"source{i % 10}\", timestamp=datetime.now()),\n ),\n )\n for i in range(100)\n]\n\nasync_tbl = await async_db.create_table(\n \"documents_async\", data=data, mode=\"overwrite\"\n)\n";

export const PyCreateTableWithNestedSchema = "# Let's add 100 sample rows to our dataset\ndata = [\n LanceSchema(\n id=f\"id{i}\",\n vector=np.random.randn(1536),\n payload=Document(\n content=f\"document{i}\",\n meta=Metadata(source=f\"source{i % 10}\", timestamp=datetime.now()),\n ),\n )\n for i in range(100)\n]\n\n# Synchronous client\ntbl = db.create_table(\"documents\", data=data, mode=\"overwrite\")\n";
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14 changes: 8 additions & 6 deletions docs/snippets/tables.mdx
Original file line number Diff line number Diff line change
Expand Up @@ -12,6 +12,8 @@ export const PyAddDataPydanticModel = "from lancedb.pydantic import LanceModel,

export const PyAddDataToTable = "import pyarrow as pa\n\n# create an empty table with schema\ndata = [\n {\"vector\": [3.1, 4.1], \"item\": \"foo\", \"price\": 10.0},\n {\"vector\": [5.9, 26.5], \"item\": \"bar\", \"price\": 20.0},\n {\"vector\": [10.2, 100.8], \"item\": \"baz\", \"price\": 30.0},\n {\"vector\": [1.4, 9.5], \"item\": \"fred\", \"price\": 40.0},\n]\n\nschema = pa.schema(\n [\n pa.field(\"vector\", pa.list_(pa.float32(), 2)),\n pa.field(\"item\", pa.utf8()),\n pa.field(\"price\", pa.float32()),\n ]\n)\n\ntable_name = \"basic_ingestion_example\"\ntable = db.create_table(table_name, schema=schema, mode=\"overwrite\")\n# Add data\ntable.add(data)\n";

export const PyAddFromDataset = "import pyarrow.dataset as ds\n\ndataset = ds.dataset(data_path, format=\"parquet\")\ndb = tmp_db\ntable = db.create_table(\"my_table\", schema=dataset.schema, mode=\"overwrite\")\ntable.add(dataset)\n";

export const PyAlterColumnsDataType = "# Change price from int32 to int64 for larger numbers\ntable.alter_columns({\"path\": \"price\", \"data_type\": pa.int64()})\n";

export const PyAlterColumnsMultiple = "# Rename, change type, and make nullable in one operation\ntable.alter_columns(\n {\n \"path\": \"sale_price\",\n \"rename\": \"final_price\",\n \"data_type\": pa.float64(),\n \"nullable\": True,\n }\n)\n";
Expand All @@ -24,13 +26,13 @@ export const PyAlterColumnsWithExpression = "# For custom transforms, create a n

export const PyAlterVectorColumn = "vector_dim = 768 # Your embedding dimension\ntable_name = \"vector_alter_example\"\ndb = tmp_db\ndata = [\n {\n \"id\": 1,\n \"embedding\": np.random.random(vector_dim).tolist(),\n },\n]\ntable = db.create_table(table_name, data, mode=\"overwrite\")\n\ntable.alter_columns(\n dict(path=\"embedding\", data_type=pa.list_(pa.float32(), vector_dim))\n)\n";

export const PyBatchDataInsertion = "import pyarrow as pa\n\ndef make_batches():\n for i in range(5): # Create 5 batches\n yield pa.RecordBatch.from_arrays(\n [\n pa.array([[3.1, 4.1], [5.9, 26.5]], pa.list_(pa.float32(), 2)),\n pa.array([f\"item{i*2+1}\", f\"item{i*2+2}\"]),\n pa.array([float((i * 2 + 1) * 10), float((i * 2 + 2) * 10)]),\n ],\n [\"vector\", \"item\", \"price\"],\n )\n\nschema = pa.schema(\n [\n pa.field(\"vector\", pa.list_(pa.float32(), 2)),\n pa.field(\"item\", pa.utf8()),\n pa.field(\"price\", pa.float32()),\n ]\n)\n# Create table with batches\ntable_name = \"batch_ingestion_example\"\ntable = db.create_table(table_name, make_batches(), schema=schema, mode=\"overwrite\")\n";
export const PyBatchDataInsertion = "import pyarrow as pa\n\ndef make_batches():\n for i in range(5): # Create 5 batches\n yield pa.RecordBatch.from_arrays(\n [\n pa.array([[3.1, 4.1], [5.9, 26.5]], pa.list_(pa.float32(), 2)),\n pa.array([f\"item{i * 2 + 1}\", f\"item{i * 2 + 2}\"]),\n pa.array([float((i * 2 + 1) * 10), float((i * 2 + 2) * 10)]),\n ],\n [\"vector\", \"item\", \"price\"],\n )\n\nschema = pa.schema(\n [\n pa.field(\"vector\", pa.list_(pa.float32(), 2)),\n pa.field(\"item\", pa.utf8()),\n pa.field(\"price\", pa.float32()),\n ]\n)\n# Create table with batches\ntable_name = \"batch_ingestion_example\"\ntable = db.create_table(table_name, make_batches(), schema=schema, mode=\"overwrite\")\n";

export const PyConsistencyCheckoutLatest = "uri = str(tmp_db.uri)\nwriter_db = lancedb.connect(uri)\nreader_db = lancedb.connect(uri)\nwriter_table = writer_db.create_table(\"consistency_checkout_latest_table\", [{\"id\": 1}], mode=\"overwrite\")\nreader_table = reader_db.open_table(\"consistency_checkout_latest_table\")\n\nwriter_table.add([{\"id\": 2}])\nrows_before_refresh = reader_table.count_rows()\nprint(f\"Rows before checkout_latest: {rows_before_refresh}\")\n\nreader_table.checkout_latest()\nrows_after_refresh = reader_table.count_rows()\nprint(f\"Rows after checkout_latest: {rows_after_refresh}\")\n";
export const PyConsistencyCheckoutLatest = "uri = str(tmp_db.uri)\nwriter_db = lancedb.connect(uri)\nreader_db = lancedb.connect(uri)\nwriter_table = writer_db.create_table(\n \"consistency_checkout_latest_table\", [{\"id\": 1}], mode=\"overwrite\"\n)\nreader_table = reader_db.open_table(\"consistency_checkout_latest_table\")\n\nwriter_table.add([{\"id\": 2}])\nrows_before_refresh = reader_table.count_rows()\nprint(f\"Rows before checkout_latest: {rows_before_refresh}\")\n\nreader_table.checkout_latest()\nrows_after_refresh = reader_table.count_rows()\nprint(f\"Rows after checkout_latest: {rows_after_refresh}\")\n";

export const PyConsistencyEventual = "from datetime import timedelta\n\nuri = str(tmp_db.uri)\nwriter_db = lancedb.connect(uri)\nreader_db = lancedb.connect(uri, read_consistency_interval=timedelta(seconds=3600))\nwriter_table = writer_db.create_table(\"consistency_eventual_table\", [{\"id\": 1}], mode=\"overwrite\")\nreader_table = reader_db.open_table(\"consistency_eventual_table\")\nwriter_table.add([{\"id\": 2}])\nrows_after_write = reader_table.count_rows()\nprint(f\"Rows visible before eventual refresh interval: {rows_after_write}\")\n";
export const PyConsistencyEventual = "from datetime import timedelta\n\nuri = str(tmp_db.uri)\nwriter_db = lancedb.connect(uri)\nreader_db = lancedb.connect(uri, read_consistency_interval=timedelta(seconds=3600))\nwriter_table = writer_db.create_table(\n \"consistency_eventual_table\", [{\"id\": 1}], mode=\"overwrite\"\n)\nreader_table = reader_db.open_table(\"consistency_eventual_table\")\nwriter_table.add([{\"id\": 2}])\nrows_after_write = reader_table.count_rows()\nprint(f\"Rows visible before eventual refresh interval: {rows_after_write}\")\n";

export const PyConsistencyStrong = "from datetime import timedelta\n\nuri = str(tmp_db.uri)\nwriter_db = lancedb.connect(uri)\nreader_db = lancedb.connect(uri, read_consistency_interval=timedelta(0))\nwriter_table = writer_db.create_table(\"consistency_strong_table\", [{\"id\": 1}], mode=\"overwrite\")\nreader_table = reader_db.open_table(\"consistency_strong_table\")\nwriter_table.add([{\"id\": 2}])\nrows_after_write = reader_table.count_rows()\nprint(f\"Rows visible with strong consistency: {rows_after_write}\")\n";
export const PyConsistencyStrong = "from datetime import timedelta\n\nuri = str(tmp_db.uri)\nwriter_db = lancedb.connect(uri)\nreader_db = lancedb.connect(uri, read_consistency_interval=timedelta(0))\nwriter_table = writer_db.create_table(\n \"consistency_strong_table\", [{\"id\": 1}], mode=\"overwrite\"\n)\nreader_table = reader_db.open_table(\"consistency_strong_table\")\nwriter_table.add([{\"id\": 2}])\nrows_after_write = reader_table.count_rows()\nprint(f\"Rows visible with strong consistency: {rows_after_write}\")\n";

export const PyCreateEmptyTable = "import pyarrow as pa\n\nschema = pa.schema(\n [\n pa.field(\"vector\", pa.list_(pa.float32(), 2)),\n pa.field(\"item\", pa.string()),\n pa.field(\"price\", pa.float32()),\n ]\n)\ndb = tmp_db\ntbl = db.create_table(\"test_empty_table\", schema=schema, mode=\"overwrite\")\n";

Expand Down Expand Up @@ -60,11 +62,11 @@ export const PyDropColumnsSingle = "# Remove the first temporary column\ntable.d

export const PyDropTable = "db = tmp_db\n# Create a table first\ndata = [{\"vector\": [1.1, 1.2], \"lat\": 45.5}]\ndb.create_table(\"my_table\", data, mode=\"overwrite\")\n\n# Drop the table\ndb.drop_table(\"my_table\")\n";

export const PyInsertIfNotExists = "import pyarrow as pa\n\ntable = db.create_table(\n \"users_example\",\n data=pa.table(\n {\n \"id\": [1, 2],\n \"name\": [\"Alice\", \"Bob\"],\n \"login_count\": [10, 20],\n }\n ),\n mode=\"overwrite\",\n)\n\nincoming_users = pa.table(\n {\n \"id\": [2, 3],\n \"name\": [\"Bobby\", \"Charlie\"],\n \"login_count\": [21, 5],\n }\n)\n\n(\n table.merge_insert(\"id\")\n .when_not_matched_insert_all()\n .execute(incoming_users)\n)\n";
export const PyInsertIfNotExists = "import pyarrow as pa\n\ntable = db.create_table(\n \"users_example\",\n data=pa.table(\n {\n \"id\": [1, 2],\n \"name\": [\"Alice\", \"Bob\"],\n \"login_count\": [10, 20],\n }\n ),\n mode=\"overwrite\",\n)\n\nincoming_users = pa.table(\n {\n \"id\": [2, 3],\n \"name\": [\"Bobby\", \"Charlie\"],\n \"login_count\": [21, 5],\n }\n)\n\n(table.merge_insert(\"id\").when_not_matched_insert_all().execute(incoming_users))\n";

export const PyMergeDeleteMissingBySource = "import pyarrow as pa\n\ntable = db.create_table(\n \"users_example\",\n data=pa.table(\n {\n \"id\": [1, 2, 3],\n \"name\": [\"Alice\", \"Bob\", \"Charlie\"],\n \"login_count\": [10, 20, 5],\n }\n ),\n mode=\"overwrite\",\n)\n\nincoming_users = pa.table(\n {\n \"id\": [2, 3],\n \"name\": [\"Bobby\", \"Charlie\"],\n \"login_count\": [21, 5],\n }\n)\n\n(\n table.merge_insert(\"id\")\n .when_matched_update_all()\n .when_not_matched_insert_all()\n .when_not_matched_by_source_delete()\n .execute(incoming_users)\n)\n";

export const PyMergeMatchedUpdateOnly = "import pyarrow as pa\n\ntable = db.create_table(\n \"users_example\",\n data=pa.table(\n {\n \"id\": [1, 2],\n \"name\": [\"Alice\", \"Bob\"],\n \"login_count\": [10, 20],\n }\n ),\n mode=\"overwrite\",\n)\n\nincoming_users = pa.table(\n {\n \"id\": [2, 3],\n \"name\": [\"Bobby\", \"Charlie\"],\n \"login_count\": [21, 5],\n }\n)\n\n(\n table.merge_insert(\"id\")\n .when_matched_update_all()\n .execute(incoming_users)\n)\n";
export const PyMergeMatchedUpdateOnly = "import pyarrow as pa\n\ntable = db.create_table(\n \"users_example\",\n data=pa.table(\n {\n \"id\": [1, 2],\n \"name\": [\"Alice\", \"Bob\"],\n \"login_count\": [10, 20],\n }\n ),\n mode=\"overwrite\",\n)\n\nincoming_users = pa.table(\n {\n \"id\": [2, 3],\n \"name\": [\"Bobby\", \"Charlie\"],\n \"login_count\": [21, 5],\n }\n)\n\n(table.merge_insert(\"id\").when_matched_update_all().execute(incoming_users))\n";

export const PyMergePartialColumns = "import pyarrow as pa\n\ntable = db.create_table(\n \"users_example\",\n data=pa.table(\n {\n \"id\": [1, 2],\n \"name\": [\"Alice\", \"Bob\"],\n \"login_count\": [10, 20],\n }\n ),\n mode=\"overwrite\",\n)\n\nincoming_users = pa.table(\n {\n \"id\": [2, 3],\n \"name\": [\"Bobby\", \"Charlie\"],\n }\n)\n\n(\n table.merge_insert(\"id\")\n .when_matched_update_all()\n .when_not_matched_insert_all()\n .execute(incoming_users)\n)\n";

Expand Down
48 changes: 46 additions & 2 deletions docs/tables/create.mdx
Original file line number Diff line number Diff line change
Expand Up @@ -19,6 +19,7 @@ import {
RsCreateTableFromArrow as RsCreateTableFromArrow,
PyCreateTableFromPydantic as CreateTableFromPydantic,
PyCreateTableNestedSchema as CreateTableNestedSchema,
PyAddFromDataset as AddFromDataset,
PyCreateTableFromIterator as CreateTableFromIterator,
TsCreateTableFromIterator as TsCreateTableFromIterator,
RsCreateTableFromIterator as RsCreateTableFromIterator,
Expand Down Expand Up @@ -217,9 +218,39 @@ for a `created_at` field.

When you run this code it, should raise the `ValidationError`.

### Use Iterators / Write Large Datasets
### Loading Large Datasets

For large ingests, prefer batching instead of adding one row at a time. Python and Rust can create a table directly from Arrow batch iterators or readers. In TypeScript, the practical pattern today is to create an empty table and append Arrow batches in chunks.
When ingesting large datasets, use `table.add()` on an existing table rather than
passing all data to `create_table()`. The `add()` method auto-parallelizes large
writes, while `create_table(name, data)` does not.

<Tip>
For best performance with large datasets, create an empty table first and then call
`table.add()`. This enables automatic write parallelism for materialized data sources.
</Tip>

#### From files (Parquet, CSV, etc.)
<Badge color="green">Python Only</Badge>

For file-based data, pass a `pyarrow.dataset.Dataset` to `table.add()`. This streams
data from disk without loading the entire dataset into memory.

<CodeGroup>
<CodeBlock filename="Python" language="Python" icon="python">
{AddFromDataset}
</CodeBlock>
</CodeGroup>

<Note>
`pa.dataset()` input is currently Python-only. TypeScript and Rust support for
file-based dataset ingestion is tracked in
[lancedb#3173](https://github.com/lancedb/lancedb/issues/3173).
</Note>

#### From iterators (custom batch generation)

When you need custom batch logic — generating embeddings on the fly, transforming
rows from an external source, etc. — use an iterator of `RecordBatch` objects.

<CodeGroup>
<CodeBlock filename="Python" language="Python" icon="python">
Expand All @@ -237,6 +268,19 @@ For large ingests, prefer batching instead of adding one row at a time. Python a

Python can also consume iterators of other supported types like Pandas DataFrames or Python lists.

#### Write parallelism

<Note title="Automatic parallelism">
For materialized data (`pa.Table`, `pd.DataFrame`, `pa.dataset()`), LanceDB
automatically parallelizes large writes — no configuration needed. Auto-parallelism
targets approximately 1M rows or 2GB per write partition.

For streaming sources (iterators, `RecordBatchReader`), LanceDB cannot determine
total size upfront. A `parallelism` parameter to control this manually is planned
but not yet exposed in Python or TypeScript
([tracking issue](https://github.com/lancedb/lancedb/issues/3173)).
</Note>

## Open existing tables

If you forget the name of your table, you can always get a listing of all table names.
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