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lancedb/docs/web/sql/dql/blob-descriptor.mdx
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Jack YeandClaude Sonnet 5 de95ed3f6d docs: overhaul curation, feature engineering, security and deployment guides (#4748)
A broad documentation pass across the areas LanceDB Enterprise and
Embedded
diverge on most:

**Data Curation** -- GPU Function execution, Slurm scheduling (and what
Slurm is, for readers new to it), blob late materialization as its own
page, joins, aggregation/profiling, sampling, near-duplicate detection,
chunking, distributed shuffle, and IVF-partition clustering.

**Feature Engineering** -- computed columns and materialized views,
restructured to lead with the Function-based path and show the SQL form
side by side with Python throughout; a single Auto Refresh page instead
of
duplicating scheduling details on every refresh page; adaptive
execution;
checkpointing; GPU and Slurm placement for refresh workers; a Training
Cache page for the PyTorch data loader's automatic cache benefit.

**Security & Governance** -- an Audit Log reference (schema, access,
grants), Secrets promoted to an ordinary catalog object with their own
SQL
DDL and a vending/rotation guide, and privilege-table fixes verified
against the authorization source.

**Deployment & Maintenance** -- Horizontal Scaling and OpenTelemetry
moved
into a real Deployment area; Automated Cleanup folded into Intelligent
Auto-Maintenance (every other maintenance decision already lived there);
RTE Compaction and Advanced Conflict Resolution documented in depth.

**Landing page** -- the Enterprise feature comparison table reorganized
(several redundant or stale rows removed, several new areas added), and
the
"why Enterprise" bullets replaced with ones tied to a concrete page
(Performance, Scale, Fault tolerance, Multicloud deployment, Simplify
operations) instead of vague promises.

Plus a full pass addressing lancedb-gatekeeper's review: a real
test-safety
bug (a quickstart test could silently overwrite and delete a
deployment's
own `frames` table), a fabricated SQL statement with no backing
implementation, an actual dedup-guarantee bug in `take_row_ids`, and
dozens
of documentation-accuracy fixes verified against source rather than
taken
on faith -- each either fixed, or left with an explicit note on why it
needs a feature or deployment owner's sign-off instead of being guessed
at.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

https://claude.ai/code/session_018PXMCbRH6i5w47TsjeEUMT

---------

Co-authored-by: Claude Sonnet 5 <noreply@anthropic.com>
2026-11-03 16:17:24 -08:00

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---
title: "BLOB_DESCRIPTOR"
sidebarTitle: "BLOB_DESCRIPTOR"
description: "The blob_descriptor() scalar function: a BlobV2 column's payload location, without reading it."
icon: file-binary
keywords: ["blob_descriptor", "sql", "blob", "large binary", "scalar function"]
availability:
embedded: unavailable
enterprise: available
---
<CodeGroup>
```sql SQL icon="database"
SELECT id, blob_descriptor(video) AS descriptor FROM videos
```
</CodeGroup>
A [BlobV2](/management/table#managed-blobs) column's bytes are not fetched by
a plain `SELECT`: that already returns `large_binary`, the same as any other
binary column. `blob_descriptor` instead returns a small struct describing
where the payload lives, without reading it. Pass one row's descriptor to
the SDK's blob file reader to open that payload directly:
<CodeGroup>
```python Python icon="python"
rows = db.execute_query("SELECT id, blob_descriptor(video) AS descriptor FROM videos").read_all().to_pylist()
with table.open_blob_file(rows[0]["descriptor"]) as reader:
payload = reader.read()
```
</CodeGroup>
A descriptor is pinned to the table version it was read at: it keeps
resolving correctly even after the table is appended to and checked out to a
newer version.
## What to read next {#next}
<CardGroup cols={2}>
<Card title="Managed blobs" icon="file-binary" href="/management/table#managed-blobs">
The BlobV2 column type this function describes.
</Card>
</CardGroup>