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lancedb/docs/web/training/observability.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: "Observability"
sidebarTitle: "Observability"
description: "Pipeline counters for diagnosing StreamingDataset bottlenecks."
icon: gauge
availability:
embedded: available
enterprise: available
---
Optimizing data loader performance can be tricky, as runtime bottlenecks are often difficult to locate across various stages of the I/O and CPU pipelines. To help distinguish bottlenecks, [`StreamingDataset`](/training/data-loading) exposes several pipeline counters: `raw_queue_depth` shows the number of loaded rows waiting to be transformed,
and `prefetch_queue_depth` is the number of transformed rows ready to be consumed. `unscanned_rows` and
`consumed_rows` show how far the current iterator has progressed.
If the `prefetch_queue_depth` is consistently zero but the `raw_queue_depth` is not, then you likely have a CPU
transformation bottleneck. You should investigate GIL bottlenecks or look for ways to optimize your transformation.
This can often be done by batching the compute work. If both `prefetch_queue_depth` and `raw_queue_depth` are
consistently zero while the consumer is waiting, I/O is the likely bottleneck. A larger read batch size or clumped
shuffling could help.
<CodeGroup>
```py Python icon=Python
import threading, time
from lancedb.streaming import StreamingDataset
ds = StreamingDataset(table, shuffle_seed=42)
def log_pipeline_health():
while True:
print(
f"unscanned={ds.unscanned_rows} "
f"raw={ds.raw_queue_depth} "
f"cooked={ds.prefetch_queue_depth} "
f"consumed={ds.consumed_rows}"
)
time.sleep(1.0)
monitor = threading.Thread(target=log_pipeline_health, daemon=True)
monitor.start()
for sample in ds:
train_step(sample)
print(
f"bytes loaded: {ds.bytes_loaded} "
f"fetch time: {ds.fetch_time:.2f}s "
f"transform time: {ds.transform_time:.2f}s"
)
```
</CodeGroup>
`bytes_loaded` measures raw Arrow buffer bytes before transformation. `bytes_loaded`, `fetch_time`, and `transform_time`
are cumulative across iterations of the same dataset instance; because work runs concurrently, the summed stage times
can exceed wall-clock time. The queue depths report rows currently waiting in the pipeline, and the progress counters
reflect the latest iterator snapshot.
## Next steps {#next}
<CardGroup cols={2}>
<Card title="PyTorch Data Loader" icon="boxes-stacked" href="/training/data-loading">
Stream, shuffle and transform training data with StreamingDataset.
</Card>
<Card title="Checkpointing" icon="floppy-disk" href="/training/checkpointing">
Save progress so a failed run can pick back up.
</Card>
</CardGroup>